Research Article Investigation of Cure Reaction, …downloads.hindawi.com/journals/jpol/2013/183463.pdfJournal of Polymers e cure kinetics and reaction mechanisms of various epoxy

Hindawi Publishing CorporationJournal of PolymersVolume 2013 Article ID 183463 17 pageshttpdxdoiorg1011552013183463

Research ArticleInvestigation of Cure Reaction RheologyVolume Shrinkage and Thermomechanical Properties ofNano-TiO2 Filled EpoxyDDS Composites

Jyotishkumar Parameswaranpillai1 Abhilash George1

Juumlrgen Pionteck2 and Sabu Thomas34

1 Department of Polymer Science and Rubber Technology Cochin University of Science and Technology Cochin Kerala 682022 India2 Leibniz-Institute for Polymer Research Dresden Hohe Strare 6 01069 Dresden Germany3 School of Chemical Sciences Mahatma Gandhi University Priyadarshini Hills Kottayam Kerala 686560 India4Centre for Nanoscience amp Nanotechnology Mahatma Gandhi University Priyadarshini Hills Kottayam Kerala 686560 India

Correspondence should be addressed to Jyotishkumar Parameswaranpillai jyotishkumarpgmailcom

Received 26 March 2013 Accepted 2 July 2013

Academic Editor Jae-Woon Nah

Copyright copy 2013 Jyotishkumar Parameswaranpillai et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

The cure reaction rheology volume shrinkage and thermomechanical behavior of epoxy-TiO2nanocomposites based on diglycidyl

ether of bisphenol A cured with 441015840-diaminodiphenylsulfone have been investigated The FTIR results show that at the initialcuring stage TiO

2acts as a catalyst and facilitates the curing The catalytic effect of TiO

2was further confirmed by the decrease in

maximum exothermal peak temperature (DSC results) however it was also found that the addition of TiO2decreases the overall

degree of cure as evidenced by lower total heat of reaction of the cured composites compared to neat epoxyThe importance of curerheology in the microstructure formation during curing was explored by using rheometry From the PVT studies it was found thatTiO2decreases the volume shrinkage behavior of the epoxy matrix The mechanical properties of the cured epoxy composites

such as tensile strength tensile modulus flexural strength flexural modulus impact strength and fracture toughness of thepolymer composites were examined The nanocomposites exhibited good improvement in dimensional thermal and mechanicalproperties with respect to neat cross-linked epoxy system FESEMmicrographs of fractured surfaces were examined to understandthe toughening mechanism

1 Introduction

Epoxy resins are widely used in industrial applications suchas matrices in composite materials and for aerospace ap-plications adhesives coating electronic circuit board-lam-inates and so forth due to their excellent mechanical andthermal properties low cost ease of processing fine adhesionto many substrates good chemical resistance good weath-ering resistance low specific weight and long pot life period[1] The major problems with epoxy are low stiffness and lowstrength compared to metals and also cured epoxy resinsare highly brittle which greatly limits their application insome areas [2] Toughness reinforcement of epoxy resins hasattracted considerable attention for over the last 30 yearsA new approach aiming to overcome this basic problem is

related to nanotechnology and uses fillers in the nanome-ter scale Nanoparticles embedded in polymer matrix haveattracted increasing interest because of the unique mechan-ical optical electrical and magnetic properties displayed bythe nanocomposites [3] Nanoparticles can significantly alterthe mechanical properties of the polymer close to a particlesurface due to the changes in polymer chain mobility Theenhancement in toughness is attributed to the size of thenanoparticles since they can provide high specific surfacearea which helps to develop new material behaviour and isdetermined by interfacial interactions resulting in uniqueproperties and completely new classes of materials [4 5]Recently many researchers have shown that the additionof nanofillers not only increases the toughness but alsostrengthens the obtained composites [6ndash8]

2 Journal of Polymers

The cure kinetics and reaction mechanisms of variousepoxy monomer and its nanocomposites with nanofillershave been studied using different methods including FTIRspectroscopy [9 10] and DSC [11 12] FTIR and DSC havebeen a useful technique for studying cure kinetics of cross-linking reactions in thermosetting epoxy FTIR spectral anal-ysis is based on the band intensity change of the functionalgroup during the reaction time at a given temperature InDSC analysis both the isothermal and the dynamic heatingexperimental modes have been used extensively to determinethe cure kinetic models and their parameters for the neatepoxy and epoxynanocomposites which are mostly curedwith amine curing agentThebasic assumption is that the heatevolution monitored and recorded by DSC is proportional tothe extent of consumption of the functional groups such asthe epoxide groups in the epoxy resin or amine groups in thecuring agent [13]

The processing of the thermoset matrix composites ismore complicated and less controlled because of their reac-tivity In this processes polymer synthesis and shaping takeplace in a single operation this involves the conversion ofliquid monomers or polymers into solid crosslinked poly-mers [14 15] In addition tendency of polymers to expand orcontract during processing is a problem that has been widelyrecognized especially for epoxy systems [16 17] Thus theknowledge of rheology and volume shrinkage behavior of theepoxy resin system is particularly necessary to have a correctcontrol of the processing mechanism and the subsequentengineering design

The very high specific surface area of nanoparticles how-ever causes the nanoparticles to attract each other due to vander Waals forces and to form agglomerates with dimensionsof several micrometers [6] It is reported that a considerableamount of improvement in mechanical properties can beachieved using very low amounts of nanofiller loadings [7 8]To extract maximum benefit from their high specific surfacenanoparticles have to be homogenously dispersed in thepolymer matrix to increase the effective interfacial surfacebetween the fillers and thematrixThemechanical propertiessignificantly depend on the dispersion of the particles inthe matrix This interfacial surface allows a good transfer ofthe applied load from the matrix to the nanoparticles Gooddispersion also results in a more uniform stress distributionand minimizes stress concentration which should increasethe general strength and modulus of the composites [1819] Nanoparticles are generally introduced into the polymermatrix by various techniques which include application ofhigh shear forces during mechanical stirring [7 20ndash22]pulsed ultrasound vibrations [23] and direct incorporationwith chemicalmethods [24 25]This avoids the agglomeratedstate

Nanoscaled TiO2has gained great interests in the last

decades because of its unique properties and good per-formance The TiO

2is extensively used in industry such

as additives for epoxies plastics and rubbers [6 26ndash30]Moreover TiO

2filled polymers arewell-known antimicrobial

materials [31ndash35] Since epoxy is a very common materialfor aerospace and automotive industry addition of TiO

2may

act as substitute for pollution treatment (in presence of UV

light TiO2generates hydroxyl radicals which can degrade

or oxidize the pollutants into more environmentally friendlyproducts) and disinfectant (photo catalytic degradation ofbacteria and grime) [35] which is a major industrial issueTiO2is well known for photo chemical degradation of toxic

chemicals UV shielding waste water purification and soforth Apart from that it is widely used in piezoelectric capac-itors solid oxide fuel cells electrode materials in lithiumbatteries energy converter in solar cells and so forth [36]

Very few studies have been reported on the epoxyTiO2

nanocomposites most of them are focused on the finalmechanical properties [37 38] However the effect of TiO

2

on cure rheology and volume shrinkage of epoxy systemshas never been investigated In this context a detailed studyin this topic is very important In this paper we presentan experimental investigation on the effect of mechanicallydispersed TiO

2on the network formation of an epoxyamine

system The effect of TiO2on the volume shrinkage was also

examined Finally we have investigated the thermomechani-cal properties of the cured epoxyTiO

2nanocomposites

2 Experimental Part21 Materials Used The epoxy resin diglycidyl ether ofbisphenol-A (DGEBA) (Lapox L-12 Atul Ltd India) wasused as the matrix material The amine hardener diaminodiphenyl sulfone (DDS) (Lapox K-10 Atul Ltd India) wasused as a cross-linker for the epoxy Nano-TiO

2 with size

around 100 nm was obtained from Riedel-de Haen (productcode 14027) Germany

22 Preparation of EpoxyTiO2Nanocomposites TiO

2nano-

particles were dispersed in DGEBA (epoxy) and mixed at180∘C using a high speed magnetic stirrer for two hours thena stoichiometric amount of DDS with an epoxy amine ratioof 2 1 was added as the curing agent and mixed well Thesolution was transferred to an open mold The compositeswere cured in the open mold at 180∘C for three hours andthen postcured at 200∘C for 2 hours Composites with TiO

2

contents of 0 1 5 and 10 g in epoxy-hardener mixture(100 g DGEBA + 35 g DDS) were prepared and the sampleswere named as neat epoxy 07 wt TiO

2 36 wt TiO

2 and

69 wt TiO2 respectively

For fourier transform infrared spectrometer (FTIR) dif-ferential scanning calorimetry (DSC) rheology and pressure-volume-temperature (PVT) observations the freshly pre-pared mixtures were immediately used or stored before usein a freezer at minus20∘C For other experiments the freshlyprepared mixtures were cured in the air oven at 180∘Cfor 3 h and then postcured at 200∘C for further 2 h Theresultant composites were then allowed to cool slowly toroom temperature

3 Characterization

31 Fourier Transform Infrared Spectroscopy In situ curingstudies were carried out using a fourier transform infrared-spectrometer EQUINOX 55 (Bruker Optik GmbH) A few

Journal of Polymers 3

milligrams of sample were placed in a sample holder and in-situ FTIR measurements were performed at 150∘C for threehours Please note that at 180∘C the reaction between epoxyand amine is too fast to be followed by in-situ FTIR analysis

32 Differential Scanning Calorimetry The noncured sam-ples were analyzed using a DSC Q1000 of TA-InstrumentsSamples of about 6mg were encapsulated in aluminumpans Modulated DSC measurements were carried out in thetemperature range from minus60∘C (5min) to 300∘C (05min)at a heating rate of 2 Kmin in N

2atmosphere with an

amplitude of plusmn031 K and a period of 40 s Please note thatat higher heating rates the curing reaction was not completeup to 300∘C Above this temperature beginning degradation(proven by TGA investigations which are not shown here)overlaps the curing reactionThus to ensure complete curingbelow 300∘C the low heating rate had to be used in thisworkThe heat of the reaction (Δ119867) was determined from thetotal heat flow of the 1st heating scan The curing enthalpy isproportional to the extent of the reaction In the compositesthe measured curing enthalpyΔ119867 is normalized to the epoxycontent (Δ119867

(corr))

33 Oscillatory Shear Rheology Rheological properties ofthe TiO

2epoxyamine mixtures during isothermal curing

were studied by the oscillatory shear measurements usinga stress-controlled ARG2 rheometer (TA Instruments) Dueto the complete vitrification of the samples a disposableparallel plate system was utilized The system consisted oftwo aluminium plates of 25mm one standard upper plateand one lower plate with drip channel which were replacedat the end of each measurement Temperature control wasachieved by a sealed environmental testing chamber (ETCsystem TA Instruments) All experiments were carried outwith 5 strain and an angular frequency of 1Hz and wereused to determine the storagemodulus (G1015840 Pa) lossmodulus(G10158401015840 Pa) tan 120575 and complex viscosity (120578lowast)

34 Pressure-Volume-Temperature Analysis The PVT mea-surements were done using a fully automated GNOMIXhigh pressuremercury dilatometer Below 200∘C the absoluteaccuracy of the instrument is of 0002 cm3g In practice thechange in specific volume as small as 00002 cm3g can beresolved reliably The cross-linking reaction was character-ized in the so-called data acquisition mode (DAQ) at 10MPaand 180∘C by following the volume shrinkage of the samplesas a function of time In order to check whether any cross-linking has taken place during the sample preparation stagesthe experimental initial specific volumes were comparedwiththose calculated initial specific volumes from the densities ofthe individual components by assuming an additive behavior(Table 1) The experimental specific volumes and calculatedspecific volumes are comparable or in other words thedeviation was within an acceptable range (1) this meansthat no curing or little curing takes place during sampling

35 Scanning Electron Microscopy Each sample was cooledand fractured in liquid nitrogen so that the morphology of

Table 1 Experimental and calculated initial specific volume epoxyTiO2 composites at 180∘C

SamplesSpecific volume

(experimental) cm3g119881E0

Specific volume(calculated) cm3g119881T0

Neat epoxy 0893 090036 wt TiO2nanocomposite 0827 0827

the composites will not be effected After that the sampleswere sputtered with gold in the Leica EM SCD050 sputtercoater (Germany) to avoid the charging effect Finally thesputtered samples were analyzed by using a Hitachi S-4800high-resolution scanning electron microscope (Japan) withan accelerating voltage of 1 kV

36 Transmission Electron Microscopy Due to the low pen-etration power of electrons in order to be able to see thenanoparticle filler distribution under the sample surface itis necessary to mount objects for examination in the electronmicroscope as very thin films Therefore samples were cutby using an ultramicrotome (ULTRACUT E from Reichert-Jung (Germany)) into 50 to 80 nm thick ultra thin films Theprepared samples were examined in an EM 902 transmissionelectron microscope (Zeiss Germany) with an acceleratingvoltage of 80 kV

37 Thermogravimetric Analysis Thermal stability of theblends was analyzed by thermogravimetric analyser (TGA)TA Instrument Mettler Toledo TGASDTA851 (USA) wasused to monitor the samples The measurements were per-formed on 3ndash5mg of the samples from room temperatureto 700∘C at a heating rate of 20∘Cmin and under nitrogenatmosphere

38 Thermomechanical Analysis The thermomechanicalproperties of neat epoxy and epoxyTiO

2composites were

measured using a TA Instruments Co Q 400 thermo-mechanical analyser (USA) The samples were scannedfrom 50 to 250∘C at a heating rate of 1∘Cmin Rectangularspecimens of 20 times 10 times 3mm3 were used for the analysis

39 Dynamic Mechanical Analysis The investigation of theviscoelastic properties was performed using dynamic me-chanical analyzer (DMA 2980 TA Instruments Co) USARectangular specimens of 40 times 10 times 3mm3 were used Theanalysis was done in single cantilever mode at a frequency of1Hz from minus100 to 300∘C and at a heating rate of 1∘Cmin

310 Tensile Properties Specimens for mechanical testingwere machined to the required dimensions from the castpanels with a cutting machine Tensile measurements wereperformed according to ASTM D 638 The measurementswere taken with a universal testing machine (Tinius OlsenCo) Model H 50 KT (UK) at a cross-head speed of10mmmin Rectangular specimens of 100 times 10 times 3mm3


3500

3367

1625

913

3000 1500 10000

02040608

1121416

Abso

rban

ce (a

u)

DDSEpoxy

Wavenumber (cmminus1)

Figure 1 FTIR spectra of epoxy monomer and DDS

were used for determining the tensile strengthThe tests wereperformed on 6 different specimens of the same sample andthe mean values were calculated

311 Flexural Properties The flexural measurements wereperformed according to ASTM D 790 The cross-head speedwas 10mmminute The measurements were taken with auniversal testing machine (Tinius Olsen Co) Model H 50KT (UK) at a cross-head speed of 10mmmin Rectangularspecimens of 100 times 10 times 3mm3 were used The flexuralmodulus was calculated from the slope of the initial portionof the flexural stress-strain curve The tests were performedon 6 different specimens of the same sample and the meanvalues were calculated

312 Impact Strength Charpy impact strength of the unmod-ified and modified epoxy resin was measured by meansof a Charpy impact test following the specifications ISO1791eA Impact tests were performed on a Zorn Stendalimpact testing machine (Germany) The dimensions of thespecimens were approximately 40 times 8 times 4mm3 At least10 successful measurements were used to obtain the meanvalues

313 Fracture Toughness Fracture toughness of the speci-mens was determined according to ASTM D 5045-99 Themeasurements were taken with a universal testing machineZwick (UPMmdashZ010) (Germany) Rectangular specimens of60mm length 10mm width and 4mm thickness were usedfor fracture toughness measurements A notch of 5mm wasmade at one edge of the specimen A natural crack was madeby a fresh razor blade at the base of the notch The analysiswas done in bending mode at room temperature At leastsix successful measurements were used to obtain the meanvalues

314 Field Emission Scanning Electron Microscopy The mor-phology of the fractured surface of crosslinked epoxy as wellas epoxy nanocomposites after the KIc test was examinedusing aULTRAFESEM (model-ultra plus)NanoTechnology

3500 3000 1500

913

16253367

10000

2

4

6

8

10 Neat epoxy

Abso

rban

ce (a

u)

0 min15 min30 min

60 min120 min


Figure 2 FTIR spectra of neat epoxyDDS system us a function ofreaction time (119879 = 150∘C)

Systems Division Carl Zeiss SMT AG GermanyThe sampleswere coated with platinum by vapor deposition using a SCD500 Sputter Coater (BAL-TEC AG Liechtenstein)

4 Results and Discussion

41 SpectroscopicAnalysis Figure 1 shows the FTIR spectra ofepoxy monomer and DDS From the FTIR spectra the mostremarkable peaks are those of the amine region of DDS Wehave strong peaks for the NH

2groups from the DDS at 1625

and 3367 cmminus1 [39] The intense signal of the epoxy ring iscentered at 913 cmminus1 due to the asymmetrical ring stretchingin which the CndashC bond stretches during the contraction ofthe CndashO bond [39]

Figure 2 reveals the FTIR spectra of pure epoxyDDSmixture at different stages of cure The epoxide band at913 cmminus1 is very evident at the beginning of the experiment(119905 = 0) The intensity of epoxide band reduces with curingtime and is almost not detectable after 90 minutes indicatingthe time for the consumption of epoxy groups On the otherhand the strong absorbances at 1625 and 3367 cmminus1 of theNH2groups from the DDS also reduce with curing time

and almost disappear after 90 minutes again indicating thetime for complete epoxyamine conversion However anevaluation of the curing kinetics is difficult since during poly-merization the spectrum between 3100 and 3600 becomescomplex the unreacted amines and hydroxyl groups overlapto a broad band and the absorbance at 1625 cmminus1 forms aftershort curing time a shoulder to the strong absorption at1594 cmminus1 caused by phenyl ring [40] Therefore the rate ofepoxyamine polymerizationwas estimated only by followingthe loss of epoxide band intensity with respect to cure time

Figure 3 shows the FTIR spectra of the 36 wt TiO2

containing epoxy nanocomposite As in the pure epoxyDDSsystem the band at 913 cmminus1 is very evident at the beginning ofthe experiment (119905 = 0) and reduces with curing time Againafter 90min it almost disappears The rate of epoxyaminepolymerization can be estimated by following the loss ofepoxide band intensity with respect to cure time In Figure 4


3500 3000 1500 10000

2

4

6

8

10

33671625

913Abso

rban

ce (a

u)

0 min15 min30 min

60 min120 min

36 wt TiO2


Figure 3 FTIR spectra of 36 wt TiO2modified epoxyDDS

system using a function of reaction time (119879 = 150∘C)

0 20 40 60 80 100 1202

4

6

8

10

12

14

16

18

20

Time (min)

Neat epoxy36 wt TiO2 modified epoxy

Inte

rgra

l abs

orba

nce a

t 913

cmminus1

Figure 4 Exponential decay behavior of epoxy resin inepoxyamine mixture during curing (dot is corresponding tothe experiment data and line corresponding to the result simulatedby 119910 = 119910

0+ 119860

1exp(minus119909119905

1)) (119879 = 150∘C)

we compare the loss of epoxy band with respect to cure timefor the pure epoxyDDS system and 36 wt TiO

2containing

epoxy nanocomposite studied We observe similar behaviorfor both systems that is a rapid decrease of epoxide bandintensitywithin the first 45min followed by a slower decreasein the next hour However the band does not completelydisappear and the intensity levels off

To evaluate the cure reaction in more detail the loss ofepoxide band with respect to cure time was simulated withMaxwellrsquos decay equation [41] (Figure 4)

119910 = 119910

0+ 119860

1exp(minus 119909119905

1

) (1)

Table 2 First-order decay constants for nanocomposites

Specimen 119905

1(min) 119910

0119860

1119877

2

Neat epoxy 3042 plusmn 181 371 plusmn 024 1504 plusmn 034 099736 wt TiO2nanocomposite 2608 plusmn 055 375 plusmn 006 1326 plusmn 011 0999

Table 3 Δ119867119905 (Corr) and 119879119901 for the TiO2epoxy composites

Samples Δ119867

119905(Jg) Δ119867

119905 (Corr) (Jg) 119879

119901(∘C)

Neat epoxy minus394 minus394 17907 wt minus353 minus355 17636 wt minus354 minus367 17669 wt minus328 minus352 177

As 119905 rarr infin 119910 rarr 1199100 Here 119860

1is a constant and 119905

1is

the relaxation time of the cure reaction and indicates therate of the epoxyamine reaction As shown in Figure 4the simulation results gave a good fit to the experimentaldata The fit parameters 119905

1 1198601 1199100 and 1198772 to assess the

quality of fit are given in Table 2 The relaxation time 1199051

decreases with filler addition due to the acceleration of theepoxyamine reaction by the presence of TiO

2particles The

increase in reaction rate was supposed to be from the highthermal conductivity and high specific surface area of theTiO2particles

42 Nonisothermal Cure Behavior Figure 5 shows differen-tial scanning calorimetry thermograms during the curing ofcomposites as obtained during first heating in modulatedDSC scan For any given specimen only one (exothermic)DSC peak was observed due to the polymerization ofDGEBAamine owing to the heat evolved when epoxy ringsare opened during their reaction with amine functionalitiesThe peak area under the baseline extrapolated at the end ofthe reaction was used to calculate the total heat of reaction(Δ119867) The maximum exothermal peak temperature (119879

119901) and

the Δ119867corr values normalized to the epoxy weight contentas a function of TiO

2concentration are reported in Table 3

From the Table it is clear that TiO2act as catalyst and facilitate

curing at the initial stage by lowering 119879119901 on the other hand

Δ119867corr tends to be smaller as higher the TiO2content This is

because the addition of TiO2dilutes the epoxy-DDS reaction

volume and also the presence of TiO2-epoxy interactions

reduces the crosslinking degree attained by the polymermatrix

43 Rheological Analysis For the in-depth understandingof cure process oscillatory shear flow measurements wereperformed under isothermal condition at three differenttemperatures (150 165 and 180∘C) to investigate the rheo-logical parameters of epoxy nanocompositesThe rheologicalprofile remains the same irrespective of the temperatureFor avoiding overlapping of the results we are giving onlythe representative rheological profile obtained at 180∘C Inthe rheological characterization of thermosets the oscillatoryshear flow measurements are preferred to those of the steady


100 150 200 250 300

0

005

01

Hea

t flow

(Wg

) exo

Neat epoxy

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

minus015

minus01

minus005

Figure 5 Variation of heat flow with respect to temperature

shear because they can be applied to amaterial not only in theliquid state but also in rubbery and glassy

The profile of change in complex viscosity as a function ofcure time at 180∘C is shown in Figure 6(a) At the beginning ofthe curing the viscosity slowly increases with time and thenat a certain point a rapid increase in viscosity is observedThereaction between epoxy and amine induces various chemicaland physical phenomena the cross-densification advancesand hence resin viscosity increases Moreover this increasein complex viscosity curves shifted to shorter times withTiO2addition due to better epoxyamine reaction by the

acceleration effect caused by TiO2particlesThe growth of the

complex viscosity follows first-order exponential equation

119910 = 119910

0+ 119860

1exp( 119909119905

1

) (2)

Figure 6(b) reveals the variation of rheological parame-ters (tan 120575 1198661015840 and 11986610158401015840) as a function of real timeconversionscale in case of neat epoxy system at 180∘C The tan 120575 valueduring the initial stages of cure is around 90 indicating theliquid nature of the material [42] As the curing progressesa rapid drop in the tan 120575 is observed corresponding to thechemical gelation of the material This behavior is typical forepoxy systems [43]

From Figure 6(b) during the early stages of the reaction119866

1015840 is below 11986610158401015840 indicating the liquid nature of the materialafter some time both 1198661015840 and 11986610158401015840 increase with the lineargrowth of the epoxy chains This is followed by a crossoverpoint (gelation point) where 1198661015840 equals 11986610158401015840 that means thesystem acts as both elastic and viscous storing and dissipatingan identical amount of energy at this point [14 42] Epoxycomposites with 07 36 and 69 wt TiO

2follow a similar

trend Figure 6(c) shows the rheological profile of the 36 wtTiO2containing epoxy composites which is representative

for all other nanocomposites studied

In the present study three criteria for gelation time whereapplied to the dynamicmechanical data First criterion is timeat 1198661015840 = 11986610158401015840 second criterion is the time at the decrease intan 120575 [44 45] A third criterion for gel point is to locate thetime at which the viscosity reaches a value of 103 Pasdots [46]For accuracy we make use of all the criteria to evaluate thegel point and taken the average of all to determine the precisegelation point to calculate the activation energy On the otherhand two criteria for vitrification time where applied foraccuracy First criteria is time at minimum tan 120575 and thesecond criteria is time at maximum 11986610158401015840 The gelation andvitrification times calculated from the rheological profiles atdifferent isothermal temperatures are listed in Table 4 Thegelation and vitrification time of the epoxyamine systemdecreases with the addition of TiO

2particles The cure

acceleration effect caused by TiO2could bring positive effect

on the processing of composite since it needs shorter pre-curetime and postcure time

In order to characterize gelation and vitrification asa function of temperature and time a TTT diagram isproposedThe concept of a time-temperature-transformation(TTT) cure diagram has been developed by Gillham andBabayevsky [47] for polymer systems and represents thetime required to reach gelation and vitrification during anisothermal cure The TTT diagram for the 07 wt TiO

2

is proposed in Figure 6(d) The transition from viscous toelastic gel is produced by the gelation transition On the otherhand transition from elastic gel to completely crosslinkedglass produced by the vitrification transition From the TTTdiagram it is clear that the behavior of the epoxy monomerdepends on the cure temperature

For better evaluation of the effect of TiO2content on rhe-

ology activation energies for polymerization were obtainedfrom gelation times by using the following differentialequation [48 49]

119889119909

119889119905

= 119860 exp (minus119864

119886

119877119879

)119891 (119909) (3)

where 119860 is the preexponential constant 119864119886is the activation

energy 119877 is the gas constant and 119879 is the absolute temper-ature The extent of the reaction is independent of the curetemperature

Integration of this equation from 119909 = 0 to 119909 = 119909gel byusing natural logarithm leads to

lnint119909gel

0

119889119909

119891 (119909)

= ln119860 + ln (119905gel) minus (119864

119886

119877119879

) (4)

Based on Flory theory [50] the extent of reaction at gel pointis constant so the previous equation can be expressed as

ln (119905gel) = constant +119864

119886

119877119879

(5)

Thus from the slope of the plot regarding the linear rela-tionship between ln (119905gel) and the inverse of temperature theapparent activation energy can be calculated

The values of ln (119905gel) obtained by the rheological testsare plotted against 1119879 in Figure 6(e)The activation energies


900 950 1000 1050 1100 1150 1200 1250 13000

10000

20000

30000

40000

50000

60000

70000C

ompl

ex v

iscos

ity

Time (s)

Neat epoxy07 wt TiO2

36 wt TiO2

69 wt TiO2

180∘C

(a)

0 500 1000 1500 2000

0

2

4

6Neat epoxy

Crossover

Time (s)

0

20

40

60

80

100

120

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(b)

600 900 1200 1500

0

2

4

6Crossover

Time (s)

0

20

40

60

80

100

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(c)

1000 1500 2000 2500 3000 3500 4000 4500

150

155

160

165

170

175

180

Time (s)

GelationVitrification

Tem

pera

ture

(∘C)

07 wt TiO2

(d)

00022 000224 000228 000232 00023668

7

72

74

76

78

8

82

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

1T (Kminus1)

Int g

el(s

)

(e)

Figure 6 (a) Exponential growth behaviors of complex viscosity during curing of epoxyTiO2nanocomposites at 180∘C (dot is corresponding

to the experiment data and line is corresponding to the result simulated by 119910 = 1199100+ 119860

1exp(119909119905

1)) (b) Rheological profile of neat epoxy

at 180∘C (c) Rheological profile of 36 wt TiO2epoxy nanocomposites at 180∘C (d)Times to gelation and vitrification for 07 wt TiO

2

modified epoxy system (e) Variation of ln (119905gel) from complex viscosity with cure temperature for the neat matrix and epoxy nanocomposites



0 2000 4000 6000 8000 10000

078

08

082

084

086

088

09

Spec

ific v

olum

e

Time (s)

(a)

(b)

Figure 7 (a) Specific volume versus curing time from PVT test (epoxyTiO2composites) at 180∘C 10MPa (b) A schematic representation of

constrained layer of polymer chains around the TiO2nanoparticles dispersed in the epoxymatrix (white-epoxy matrix black-TiO

2 particles

red-constrained polymer chains)

have been established from the plot The activation energyvalues are 65 plusmn 5 63 plusmn 3 63 plusmn 2 and 63 plusmn 2 for neatepoxy 07 wtTiO

2epoxy 36 wtTiO

2epoxy and 69 wt

TiO2epoxy composite respectively In comparison to amine

cured DGEBA epoxy the amine cured DGEBATiO2com-

posites exhibit lower activation energies These results vali-date our FTIR and DSC studies

44 Pressure Volume Temperature Studies The typical iso-thermal curing of thermosetTiO

2based composites is

accompanied by the polymerization shrinkage and vitrifi-cation of the thermoset-rich phase The material shrinkagethat occurs during curing can adversely affect the desiredtolerance of the final product and hence a PVT study isnecessary for thermosetting composites Pressure-volume-temperature characterization is a well-known tool for theinvestigation of change in specific volume with respect tocure time for epoxy systems Figure 7(a) gives the changein specific volume data obtained for neat epoxyDDS and36 wtTiO

2epoxyDDSmixtures with respect to cure time

The absolute specific volume decreases with TiO2content due

to the higher dense TiO2nano filler in the epoxy matrix A

temperature of 180∘C and a pressure of 10MPa were appliedfor 13 hours during which a sharp decrease in the specificvolume was observed for both neat epoxy and compositedue to the in-situ epoxy-amine reaction (volume shrinkage)[51ndash53] After heating for three hours the specific volumereached a constant value for compositesThe beginning of thefinal plateau region corresponds to the vitrification processalthough at this stage the curing reaction could continueslowly

The change in specific volume is 005847 cm3g and005061 cm3g for pure epoxy and epoxy composites respec-tively and is a indirect measure of volume shrinkage

Decrease in volume shrinkage for epoxyTiO2composites

can be explained as follows The addition of TiO2dilutes the

epoxy-DDS reaction volume Moreover presence of denseTiO2nano filler may increase the viscosity of the system and

hence progressively decrease the relative volume shrinkageMoreover due to the high surface to volume ratio of nanoTiO2 epoxy polymeroligomer get attached to the filler

surface which generates a constrained polymer around thefiller surface as depicted in Figure 7(b) These constrainedlayer of polymer chains does not or only slightly undergoshrinkage due the presence of rigid TiO

2particles

45 Micro- and Nanostructure of the Nanocomposites

451 Scanning Electron Microscopy (SEM) The surface mor-phology of the cured nanocomposites was investigated bySEM SEM micrographs were taken for all the compositesFigure 8(a) shows the SEM micrograph of the neat epoxysystem which reveals a single phase Even though we brokethe sample in liquid nitrogen the surfacemorphology of neatepoxy look fractured because of the brittle nature of the con-trol epoxy On the other hand SEMmicrograph with 07 wtTiO2filler content (Figure 8(b)) is flat and smooth and quiet

nicely form line boundaries at the interface between the pureepoxy matrix The filler catalyses the epoxy polymerizationand crosslinking and the interfaces are the contact areas of theapproaching polymerization front The apparent roughnessof the surface increases with TiO

2content Figure 8(c) shows

a SEM micrograph of the 36 wt TiO2modified epoxy

which reveals a similar morphology as observed for 07 wtTiO2filler content When the concentration was increased to

69 wtTiO2 particles aremore agglomerated (Figure 8(d))

[24] As mentioned before even though the neat epoxy wasfractured in liquid nitrogen there was observed fracture step


edges due to the highly brittle nature of the material Onthe other hand fracture step edges are absent in the caseof composites with 07 wt TiO

2and 36 wt TiO

2due to

increased ductility of the epoxy matrix

452 Transmission Electron Microscopy For better under-standing of the dispersion of the TiO

2in the epoxy matrix

TEM micrographs were taken TEM is a straightforwardtechnique to visualize quality of the dispersion of nanopar-ticles within epoxy matrix The micrographs obtained fromthe sections of the nanocomposites reveal the presence ofindividual TiO

2particles embedded in the epoxy matrix

Figure 9(a) shows a TEM image of the neat epoxy it ishomogeneous with a single phase Figure 9(b) shows a TEMimage of epoxy modified with 07 wt TiO

2 there were a

few agglomerates The size of the particles varies around100 nm A similar morphology was observed for 36 wtTiO2and 69 wt TiO

2modified epoxy system (Figures 9(c)

and 9(d)) but agglomerates of particles appear The particleagglomerates are due to weak van derWaals attraction forceswhich are higher for smaller particles leading them to poordispersion

46 Thermal Stability Thermal stability of the neat epoxyand TiO

2nanocomposites was studied by TGA TGA and

DTG (derivative thermogram) curves for all the cross-linkedcomposites are given in Figures 10(a) and 10(b) respectivelyFrom the thermograms (Figure 10(a)) nano TiO

2filled com-

posites show relatively less thermal decomposition than theneat crosslinked epoxy In general the decomposition startedat around 350∘C and was completed at around 500∘C Theaverage weight loss of around 1-2 up to 300∘C is due to therelease of moisture if any On the other hand the weight lossabove 350∘C is related to the decomposition of the polymerThe main degradation peak in the composites occurredbetween 390 and 470∘C where 70ndash80 of the degradationoccurred Beyond the main degradation stage all the volatilematerials were driven off from the sample resulting in theresidual char The residual of the composites was betterthan the neat epoxy due to the presence of the thermally stableTiO2particles For better understanding the thermal stability

of the nanocomposites their weight percentage at differenttemperatures were taken and are given in Table 5 it wouldimmediately point out that for temperatures up to 400∘C(the first 4 rows) little difference appears for different loadedcomposites On the contrary above 400∘C (500 to 700∘C) thestabilizing effect of the filler becomes clear each column valueis greater than that of the column on the left The final (at700∘C) mass percent lefts from Table 5 are 125 173 192 and237 for the loadings of 0 07 36 and 69 wt respectivelyIt means that in the first case still a left mass from neatmatrix is 125 if we add the mass left to the different loadingin the next values such as to obtain roughly 125 + 07 =132 125 + 36 = 161 125 + 69 = 194 If we substrate thefinal (at 700∘C)mass percent left with these calculated valuesthen we have 173 minus 132 = 41 192 minus 161 = 31 237 minus194 = 43 this suggest that residual of the compositeswas better that neat epoxy system The temperature at which

decomposition rate has its maximum can be calculated fromthe DTG curves shown in Figure 10(b)The thermal stabilityof composites is more evident from DTG curves where themain degradation for composites is comparatively smallerthan that of the neat epoxy while the main degradationtemperature remains unaffected

47 Thermomechanical Analysis Thermal expansion behav-iour of the nanocomposites was measured using a TMA toinvestigate the effect of TiO

2on the dimensional change of

the epoxy nanocomposite samples The TMA thermogramsof cured epoxy nanocomposites are shown in Figure 11 Fromthe thermograms the dimensions increase with increase intemperature is visible During heating the nanocompositesexpand and then undergo a glassy-to-rubbery transformation(119879

119892) (at around 200∘C) it then continues to expand in the

rubbery phase with a greater liner expansion coefficientshowing the normal expansion behaviour of rubber stateIn neat epoxy system drop in the dimension change nearto 119879119892was observed The observed drop in the dimension

change near to 119879119892is due to relaxation of below 119879

119892frozen

nonequilibrium states of the cured samples [53] It is impor-tant tomention that the insertedNPs or the associatedmixingavoided the freezing of such local sites in the nanocompositesFrom the plot it can be concluded that the dimensionalstability of crosslinked epoxy remains unaltered by theaddition of nanoparticles

48 Dynamic Mechanical Analysis The storage modulusdemonstrates strength and the stiffness Figure 12(a) showsthe storage modulus curves of the epoxy composites Fromthe profile the storage modulus values of the epoxy nano-composites were higher than the neat crosslinked epoxy forall temperatures The rigid TiO

2particles improved the stiff-

ness of the epoxy matrix composites especially for 69 wtTiO2modified epoxy nanocomposites There is an inflection

point at around 200∘Cwhich indicates the transition from thesolid state to the rubbery state that is the glass transition (119879

119892)

of the system Loss modulus curves (Figure 12(b)) indicatethe energy dissipation and can be used to measure theviscous component of the material The loss modulus isgreater for the composites the dispersed TiO

2dissipates

energy due to resistance against viscoelastic deformation ofthe surrounding epoxy matrix Only one peak is observedfor the entire system the peak corresponds to the 119879

119892of the

crosslinked epoxy phase It is important to mention that thepeak is observed at lower temperature for the compositeswhich indicates slightly reduced crosslinking density for thecomposites

49 Mechanical Tests Tensile tests were conducted to mea-sure the stressndashstrain behavior of different wt nanocompos-ites under uniaxial tension The stress-strain behavior fromthe tensile tests is given in Table 6 It can be seen that additionof filler shows slight improvement in the tensile propertiesof the epoxy system The modulus strength and ductilitywere approximately stable with fluctuations for the ductility


5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)

Figure 8 SEM micrographs of epoxy nanocomposites (a) neat epoxy (b) 07 wt TiO2 (c) 36 wt TiO

2 and (d) 69 wt TiO

2

Table 4 Gelation and vitrification times for the TiO2epoxy composites

119879 (∘C) Gelation time (sec) of the epoxy phase Average of all thethree parameters (s)

Vitrification time (sec) of the epoxy phase(1198661015840 = 11986610158401015840) (s) tan 120575Max (s) 120578

lowast (s) tan 120575 (s) Max 11986610158401015840 (s)Neat epoxy

150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452

07 wt TiO2 composites150 3939 3534 3470 3648 4415 4475165 2174 2008 1992 2058 2295 2295180 1145 1024 1066 1078 1265 1323




1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)

Figure 9 TEMmicrographs of epoxy nanocomposites (a) neat epoxy (b) 07 wt TiO2 (c) 36 wt TiO

2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)

Figure 10 (a) TGA curves for epoxy nanocomposites (b) DTG curves for epoxy nanocomposites


Table 5 TGA data of epoxy composites at different temperatures

Temperature(∘C)

residueNeat 07 wt TiO2 36 wt TiO2 69 wt TiO2

100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)

Figure 11 TMA curves for epoxy nanocomposites

and an apparent moderate increase (10) for modulus andstrength

The flexural properties of the epoxy composites aregiven in Table 7 With filler addition the modulus increasedparticularly with 69 wt TiO

2addition on the other hand

the strain and strength decreased The flexural load is acombination of tensile and compressive load and thereforecompressive modulus should be increased by addition of stifffillers one could expect that the flexural modulus wouldrather increase with TiO

2addition When the composites

were subjected to flexural bending the TiO2particles are not

able to transfer the applied load but hinder the movementof epoxy resins molecular chains This leads to stress withinthe materials so that the bend fracture strength of materialdecreases [36]

The impact toughness of a material describes the energyrequired to break the specimenThemagnitude of the impactstrength reflects the ability of the material to resist impactThe impact strength of the cross-linked epoxy and epoxycomposites is shown in Figure 13 Addition of TiO

2particles

enhanced the impact strength of the neat epoxy slightly butnot for 69 wt TiO

2 The increase in the impact strength

can be attributed to the increased toughness of the matrix

upon filler additionThe nanometer-sized TiO2particles with

good dispersion are able to block the propagation of cracksthrough the polymerThis is assigned to the reinforcing effectof nano-TiO

2 The impact properties of polymers are mainly

enhanced by small particles with low aspect ratio since largeparticles can act as crack initiation sites However largefiller content (69 wt) made it more difficult for dispersionand easier for nanosized particle to ldquoagglomeraterdquo Sinceagglomerated particles make it possible to generate defectsstress concentration will likely occur within the epoxy due toexternal force resulting in decreased impact strength

Nanocomposites simultaneously improve the fracturetoughness as well as the stiffness of a neat polymer Theresistance of a material to crack initiation and propagationcan be explained in terms of fracture toughness We expressthe fracture toughness of the cured epoxy resin and itscomposites in terms of the stress intensity factor 119870IC Thevalue of the stress intensity factor (119870IC) was calculated using(1) [41]

Stress intensity factor 119870IC =119876119875119886

12

119887119889

(6)

where 119875 is the load at the initiation of a crack is the cracklength 119887 is the breadth of the specimen 119889 is the thickness ofthe specimen and 119876 is the geometry constant119876 is calculated using the following equation

119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)

The variation of fracture toughness with filler content is alsogiven in Figure 13The fracture toughness increases negligibly(by 8) with the addition of TiO

2at intermediate concen-

trations However when the TiO2content was increased to

69 wt therewas a dramatic decrease in119870IC even lower thanthat of the control neat crosslinked epoxy system due to theagglomeration of TiO

2particles

FESEM analysis of the fracture surfaces of the TiO2-

filled crosslinked epoxy network composites can give aninsight into the cause and location of failure as well as thedispersion state of the particles within the epoxy matrixFigure 14 shows FESEMmicrographs of the samples after the119870IC fracture tests The FESEM fracture micrographs after thetensile flexural and impact tests were similar to those of the119870IC fractured samples It is well known that the presenceof rigid fillers may induce several toughening mechanismsin epoxy matrices this includes crack deflection [54 55]plastic deformation [56 57] and crack front pinning [58]Some of these toughening mechanisms was observed thefor epoxyTiO

2composites Figure 14(a) shows the fracture

surface of the neat crosslinked epoxy it reveals a brittlebehavior characterized by large smooth areas typically flatand the crack propagated uninterrupted in the direction ofthe applied loadThe nanoparticle reinforced composites andon the other hand exhibited rougher fracture surfaces asshown in Figures 14(b)ndash14(d) Nanoparticle agglomerates of


Table 6 Tensile properties of the epoxy modified nanocomposites

Sample Tensile strengthMPa

Tensile modulusGPa

Tensile elongation

Ductility(area under the stressstrain curves)

Neat epoxy 51 plusmn 2 23 plusmn 01 399 plusmn 02 12107 wt TiO2 55 plusmn 3 25 plusmn 01 423 plusmn 03 13636 wt TiO2 56 plusmn 3 26 plusmn 01 388 plusmn 03 12469 wt TiO2 57 plusmn 2 27 plusmn 01 412 plusmn 02 135

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)

Figure 12 (a) Storage modulus curves for epoxy nanocomposites (b) Loss modulus curves for epoxy nanocomposites

Table 7 Flexural properties of the epoxymodified nanocomposites

SampleFlexuralstrengthMPa

FlexuralmodulusMPa

Flexuralelongation

Neat epoxy 110 plusmn 55 33 plusmn 02 545 plusmn 0307 wt TiO2 91 plusmn 4 31 plusmn 01 374 plusmn 0236 wt TiO2 64 plusmn 37 35 plusmn 01 203 plusmn 0169 wt TiO2 77 plusmn 38 42 plusmn 02 214 plusmn 01

a few micrometers size can be seen for all the samples alongwith individual nanoparticles The FESEM micrographs ofthe 07 wt filler content reveal the prevention of crackpropagation by the agglomerates of TiO

2and the crack

seems to be deviated from the original path and hence moreenergy is needed for the crack propagation Some of theTiO2particles were pulled out from the epoxy matrix by

the application of the external load so that smooth blackholes remain visible (Figure 14(b)) The latter indicates abreakdown of the fillermatrix interface which would reduceinteractions between crack and particle and subsequentlyforce the crack to breakaway at lower stresses This couldexplain why the measured fracture toughness improvementwas low [59]

3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06

Impact energy (kJm2)

Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2

Figure 13 Impact strength and fracture toughness of epoxy nano-composites

With increase in particle loading the number of particlesincreased this causes particle-particle interaction rather thanthe particle-matrix interaction Hence the particles begin toagglomerate and form lumps which eventually affected the


(a)

(b)

(c)

(d)

Figure 14 Scanning electron micrographs of failed surfaces of nanocomposites (a) neat epoxy (b) 07 wt TiO2 (c) 36 wt TiO

2 and (d)

69 wt TiO2

van der Waals interaction between the polymer chains andthat may cause a decrease in properties The agglomeratesof TiO

2are believed to cause high stress concentrations

in the polymer matrix near the particle edges which willfacilitate failure during the fracture tests In the case of

36 wt TiO2(Figure 14(c)) a morphology similar to 07 wt

TiO2was observed the particles are more agglomerated but

these agglomerates not act as failure sites and hence betterproperties compared to neat epoxy The particle agglom-erates remaining in the matrix should be small enough


to not induce a brittle and detrimental failure in the waylike ldquolargerdquo particles would On the other hand when theconcentration was increased to 69 wt TiO

2(Figure 14(d))

the fracture morphology was quite different from the rest ofthe samples with larger particle agglomerates However theparticle agglomerates were large enough to induce a brittleand detrimental failure in the way ldquolargerdquo particles would doand hence a decline in mechanical properties

5 Conclusion

The catalytic effect of TiO2nanoparticle on epoxyamine

reaction was carefully analyzed using FTIR and DSC studiesThis was further confirmed by rheological studies The gela-tion time was decreased with the addition of TiO

2nanofiller

due to the acceleration effect caused by the nanoparticleson the epoxyamine reaction PVT studies reveal that smallamount of TiO

2can potentially reduce the volume shrink-

age behavior of epoxy The effect of filler loading on thethermal and mechanical properties and the morphologywere investigated TiO

2is an effective reinforcement for

epoxy system for high performance applicationsThe thermalexpansion behaviour was not influenced by the addition ofTiO2 Similarly thermal stability was enhanced negligibly by

the addition of TiO2nanoparticles The DDS-cured epoxy

nanocomposites have a single 119879119892corresponding to that of the

epoxy phase which shows only minor decrease with TiO2

content and was close to 119879119892of the pure cross-linked epoxy

system Storage modulus results reveal better stiffness (40increase (MPa)) for the 69 wt TiO

2composites The rigid

TiO2particles have no effect or little effect on the mechanical

properties of the epoxy system however modulus increasesat some point Morphological investigation of the 119870IC frac-ture surface indicates that the slight improvement in prop-erties of the composites can be ascribed to the presence ofthe TiO

2nanoparticles in the epoxy which leads to increased

surface roughness and hence energy dissipated during thepropagation of the crack However when the concentrationof filler is more than a critical value the particles were moreagglomerated and the particle agglomerates are large enoughto induce a brittle and detrimental failure

Conflict of Interests

The authors do not have any direct financial relation with thecommercial identities

Acknowledgments

Jyotishkumar Parameswaranpillai acknowledges the Depart-ment of Science and Technology Government of India forthe financial support under INSPIRE Faculty Fellowship(IFA-CH-16)

References

[1] K Varma and V B Gupta ldquoThermosetting resinmdashpropertiesrdquoComprehensive Composite Materials vol 2 pp 1ndash56 2003

[2] P Jyotishkumar J Pionteck R Haszligler S M George UCvelbar and S Thomas ldquoStudies on stress relaxation andthermomechanical properties of poly(acrylonitrile-butadiene-styrene)modified epoxy-amine systemsrdquo IndustrialampEngineer-ing Chemistry Research vol 50 pp 4432ndash4440 2011

[3] J S Tsuji A D Maynard P C Howard et al ldquoResearchstrategies for safety evaluation of nanomaterials part IV riskassessment of nanoparticlesrdquo Toxicological Sciences vol 89 no1 pp 42ndash50 2006

[4] M Antonietti and C Goltner ldquoSuperstructures of functionalcolloids chemistry on the nanometer scalerdquo AngewandteChemie vol 36 no 9 pp 910ndash928 1997

[5] G Schmid ldquoLarge clusters and colloids Metals in the embry-onic staterdquo Chemical Reviews vol 92 no 8 pp 1709ndash1727 1992

[6] P Carballeira and F Haupert ldquoToughening effects of titaniumdioxide nanoparticles on TiO

2epoxy resin nanocompositesrdquo

Polymer Composites vol 31 no 7 pp 1241ndash1246 2010[7] B Wetzel F Haupert and F Zhang ldquoEpoxy nanocomposites

with high mechanical and tribological performancerdquo Compos-ites Science and Technology vol 63 no 14 pp 2055ndash2067 2003

[8] R P Singh M Zhang and D Chan ldquoToughening of a brittlethermosetting polymer effects of reinforcement particle sizeand volume fractionrdquo Journal of Materials Science vol 37 no4 pp 781ndash788 2002

[9] L Guadagno L Vertuccio A Sorrentino et al ldquoMechanical andbarrier properties of epoxy resin filledwithmulti-walled carbonnanotubesrdquo Carbon vol 47 no 10 pp 2419ndash2430 2009

[10] G C Huang and J K Lee ldquoIsothermal cure characterizationof fumed silicaepoxy nanocomposites the glass transitiontemperature and conversionrdquo Composites A vol 41 no 4 pp473ndash479 2010

[11] W K Goertzen X Sheng M Akinc and M R KesslerldquoRheology and curing kinetics of fumed silicacyanate esternanocompositesrdquo Polymer Engineering and Science vol 48 no5 pp 875ndash883 2008

[12] M Harsch J Karger-Kocsis and M Holst ldquoInfluence of fillersand additives on the cure kinetics of an epoxyanhydride resinrdquoEuropean Polymer Journal vol 43 no 4 pp 1168ndash1178 2007

[13] P Jyotishkumar J Pionteck L Hauszligler G Adam andS Thomas ldquoA novel hydroxyapatiteethylene-vinyl acetatecopolymer 66 composite for hard tissue regenerationrdquo Journalof Macromolecular Science B vol 51 no 1 pp 1ndash11 2012

[14] P Jyotishkumar S M George P Moldenaers and S ThomasldquoDynamics of phase separation in poly(acrylonitrile-butadiene-styrene)-modified epoxyDDS system kinetics and viscoelasticeffectsrdquo Journal of Physical Chemistry B vol 114 no 42 pp13271ndash13281 2010

[15] Y Liu X Zhong and Y Yu ldquoGelation behavior of ther-moplastic-modified epoxy systems during polymerization-induced phase separationrdquo Colloid and Polymer Science vol288 no 16-17 pp 1561ndash1570 2010

[16] M Holst K Schanzlin M Wenzel J Xu D Lellinger and IAlig ldquoTime-resolved method for the measurement of volumechanges during polymerizationrdquo Journal of Polymer Science Bvol 43 no 17 pp 2314ndash2325 2005

[17] J Jose K Joseph J Pionteck and S Thomas ldquoPVT behavior ofthermoplastic poly(styrene-co-acrylonitrile)-modified epoxysystems relating polymerization-induced viscoelastic phaseseparation with the cure shrinkage performancerdquo Journal ofPhysical Chemistry B vol 112 no 47 pp 14793ndash14803 2008


[18] M Z Rong M Q Zhang H Liu H M Zeng B Wetzel andK Friedrich ldquoMicrostructure and tribological behavior of poly-meric nanocompositesrdquo Industrial Lubrication and Tribologyvol 53 no 2 pp 72ndash77 2001

[19] M A L Manchado L Valentini J Biagiotti and J MKenny ldquoThermal and mechanical properties of single-walledcarbon nanotubes-polypropylene composites prepared by meltprocessingrdquo Carbon vol 43 no 7 pp 1499ndash1505 2005

[20] M Avella M E Errico S Martelli and E Martuscelli ldquoPrepa-ration methodologies of polymer matrix nanocompositesrdquoApplied Organometallic Chemistry vol 15 no 5 pp 435ndash4392001

[21] H R Dennis D L Hunter D Chang S Kim J L White andJ W Cho ldquoNanocomposites the importance of processingrdquoPlastics Engineering vol 57 no 1 pp 56ndash60 2001

[22] J W Cho and D R Paul ldquoNylon 6 nanocomposites by meltcompoundingrdquo Polymer vol 42 no 3 pp 1083ndash1094 2001

[23] Q Wang H Xia and C Zhang ldquoPreparation of poly-merinorganic nanoparticles composites through ultrasonicirradiationrdquo Journal of Applied Polymer Science vol 80 no 9pp 1478ndash1488 2001

[24] T Adebahr C Roscher and J Adam ldquoReinforcing nanopar-ticles in reactive resinsrdquo European Coatings Journal no 4 pp144ndash149 2001

[25] S Kang S I Hong C R Choe M Park S Rim and J KimldquoPreparation and characterization of epoxy composites filledwith functionalized nanosilica particles obtained via sol-gelprocessrdquo Polymer vol 42 no 3 pp 879ndash887 2001

[26] G Xian RWalter and F Haupert ldquoA synergistic effect of nano-TiO2and graphite on the tribological performance of epoxy

matrix compositesrdquo Journal of Applied Polymer Science vol 102no 3 pp 2391ndash2400 2006

[27] M Sangermano G Matucelli E Amerio et al ldquoPreparationand characterization of nanostructured TiO

2epoxy polymeric

filmsrdquo Macromolecular Materials and Engineering vol 291 no5 pp 517ndash523 2006

[28] R J Nussbaumer W R Caseri P Smith and T TervoortldquoPolymer-TiO

2nanocomposites a route towards visually trans-

parent broadband UV filters and high refractive index materi-alsrdquo Macromolecular Materials and Engineering vol 288 no 1pp 44ndash49 2003

[29] MXiong S Zhou BO YouGUGuangxin andLWu ldquoEffectof preparation of titania sol on the structure and propertiesof acrylic resintitania hybrid materialsrdquo Journal of PolymerScience B vol 42 no 20 pp 3682ndash3694 2004

[30] Y Tong Y Li F Xie and M Ding ldquoPreparation and char-acteristics of polyimide-TiO

2nanocomposite filmrdquo Polymer

International vol 49 no 11 pp 1543ndash1547 2000[31] H Segawa K Tateishi Y Arai K Yoshida and H Kaji

ldquoPatterning of hybrid titania film using photopolymerizationrdquoThin Solid Films vol 466 no 1-2 pp 48ndash53 2004

[32] M D Soucek A H Johnson L E Meemken and J MWegner ldquoPreparation of nano-sized UV-absorbing titanium-oxo-clusters via a photo-curing ceramer processrdquo Polymers forAdvanced Technologies vol 16 no 2-3 pp 257ndash261 2005

[33] P V Kamat ldquoPhotochemistry on nonreactive and reactive(semiconductor) surfacesrdquo Chemical Reviews vol 93 no 1 pp267ndash300 1993

[34] J C Yu W Ho J Yu H Yip and P K Wong ldquoEfficientvisible-light-induced photocatalytic disinfection on sulfur-doped nanocrystalline titaniardquo Environmental Science amp Tech-nology vol 39 no 4 pp 1175ndash1179 2005

[35] J C Yu W Ho J Lin H Yip and P K Wong ldquoPhotocatalyticactivity antibacterial effect and photoinduced hydrophilicity ofTiO2films coated on a stainless steel substraterdquo Environmental

Science amp Technology vol 37 no 10 pp 2296ndash2301 2003[36] A Chatterjee andM S Islam ldquoFabrication and characterization

of TiO2-epoxy nanocompositerdquoMaterials Science and Engineer-

ing A vol 487 no 1-2 pp 574ndash585 2008[37] K S Huang Y H Nien J S Chen T R Shieh and J W Chen

ldquoSynthesis and properties of epoxyTiO2composite materialsrdquo

Polymer Composites vol 27 no 2 pp 195ndash200 2006[38] A AWazzan H A Al-Turaif andA F Abdwlkader ldquoInfluence

of submicron TiO2particles on the mechanical properties and

fracture characteristics of cured epoxy resinrdquo Polymer-PlasticsTechnology and Engineering vol 45 no 10 pp 1155ndash1161 2006

[39] A Sabra T M Lam J P Pascault M F Grenier-Loustalotand P Grenier ldquoCharacterization and behaviour of epoxy-baseddiaminodiphenylsulphone networksrdquo Polymer vol 28 no 6pp 1030ndash1036 1987

[40] T M Don and J P Bell ldquoFourier transform infrared analysis ofpolycarbonateepoxy mixtures cured with an aromatic aminerdquoJournal of Applied Polymer Science vol 69 no 12 pp 2395ndash24071998

[41] P Jyotishkumar E Abraham S M George et al ldquoPrepa-ration and properties of MWCNTspoly(acrylonitrile-styrene-butadiene)epoxy hybrid compositesrdquo Journal of Applied Poly-mer Science vol 127 no 4 pp 3093ndash3103 2013

[42] P Jyotishkumar P Moldenaers S M George and SThomas ldquoViscoelastic effects in thermoplastic poly(styrene-acrylonitrile)-modified epoxy-DDM system during reactioninduced phase separationrdquo Soft Matter vol 8 no 28 pp3452ndash7462 2012

[43] W Gan G Zhan MWang Y Yu Y Xu and S Li ldquoRheologicalbehaviors and structural transitions in a polyethersulfone-modified epoxy system during phase separationrdquo Colloid andPolymer Science vol 285 no 15 pp 1727ndash1731 2007

[44] S Poncet G Boiteux J P Pascault et al ldquoMonitoring phaseseparation and reaction advancement in situ in thermoplas-ticepoxy blendsrdquo Polymer vol 40 no 24 pp 6811ndash6820 1999

[45] S Swier and B vanMele 1998 Polymer Network Preprints P12Trondheim

[46] I Alig and W Jenninger ldquoCuring kinetics of phase separatingepoxy thermosets studied by dielectric and calorimetric investi-gations a simple model for the complex dielectric permittivityrdquoJournal of Polymer Science B vol 36 no 13 pp 2461ndash2470 1998

[47] J K Gillham and P G Babayevsky ldquoEpoxy thermosetting sys-tems dynamic mechanical analysis of the reactions of aromaticdiamines with the diglycidyl ether of bisphenol Ardquo Journal ofApplied Polymer Science vol 17 no 7 pp 2067ndash2088 1973

[48] P A Oyanguren and R J J Williams ldquoCure of epoxy novolacswith aromatic diamines I Vitrification gelation and reactionkineticsrdquo Journal of Applied Polymer Science vol 47 no 8 pp1361ndash1371 1993

[49] J M Barton D C L Greenfield and K A Hodd ldquoSome effectsof structure on the cure of glycidylether epoxy resinsrdquo Polymervol 33 no 6 pp 1177ndash1186 1992

[50] P J Flory Principles of Polymer Chemistry Universidad deCornell Ithaca NY USA 1953

[51] P Jyotishkumar J Pionteck C Ozdilek et al ldquoRheologyand pressure-volume-temperature behavior of the thermoplas-tic poly(acrylonitrile-butadiene-styrene)-modified epoxy-DDSsystem during reaction induced phase separationrdquo Soft Mattervol 7 no 16 pp 7248ndash7256 2011


[52] J A Ramos N Pagani C C Riccardi J Borrajo S N Goyanesand I Mondragon ldquoCure kinetics and shrinkage model forepoxy-amine systemsrdquo Polymer vol 46 no 10 pp 3323ndash33282005

[53] P Jyotishkumar E Logakis S M George et al ldquoPreparationand properties of multiwalled carbon nanotubeepoxy-aminecompositesrdquo Journal of Applied Polymer Science vol 127 no 4pp 3063ndash3073 2013

[54] K T Faber and A G Evans ldquoCrack deflection processesmdashITheoryrdquo Acta Metallurgica vol 31 no 4 pp 565ndash576 1983

[55] K T Faber and A G Evans ldquoCrack deflection processesmdashIIExperimentrdquoActaMetallurgica vol 31 no 4 pp 577ndash584 1983

[56] T Kawaguchi and R A Pearson ldquoThe moisture effect onthe fatigue crack growth of glass particle and fiber reinforcedepoxies with strong and weak bonding conditions part 2a microscopic study on toughening mechanismrdquo CompositesScience and Technology vol 64 no 13-14 pp 1991ndash2007 2004

[57] A J Kinloch D Maxwell and R J Young ldquoMicromechanismsof crack propagation in hybrid-particulate compositesrdquo Journalof Materials Science Letters vol 4 no 10 pp 1276ndash1279 1985

[58] J Spanoudakis and R J Young ldquoCrack propagation in a glassparticle-filled epoxy resinrdquo Journal of Materials Science vol 19no 2 pp 473ndash486 1984

[59] B Wetzel P Rosso F Haupert and K Friedrich ldquoEpoxynanocompositesmdashfracture and tougheningmechanismsrdquo Engi-neering Fracture Mechanics vol 73 no 16 pp 2375ndash2398 2006

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


The cure kinetics and reaction mechanisms of variousepoxy monomer and its nanocomposites with nanofillershave been studied using different methods including FTIRspectroscopy [9 10] and DSC [11 12] FTIR and DSC havebeen a useful technique for studying cure kinetics of cross-linking reactions in thermosetting epoxy FTIR spectral anal-ysis is based on the band intensity change of the functionalgroup during the reaction time at a given temperature InDSC analysis both the isothermal and the dynamic heatingexperimental modes have been used extensively to determinethe cure kinetic models and their parameters for the neatepoxy and epoxynanocomposites which are mostly curedwith amine curing agentThebasic assumption is that the heatevolution monitored and recorded by DSC is proportional tothe extent of consumption of the functional groups such asthe epoxide groups in the epoxy resin or amine groups in thecuring agent [13]

The processing of the thermoset matrix composites ismore complicated and less controlled because of their reac-tivity In this processes polymer synthesis and shaping takeplace in a single operation this involves the conversion ofliquid monomers or polymers into solid crosslinked poly-mers [14 15] In addition tendency of polymers to expand orcontract during processing is a problem that has been widelyrecognized especially for epoxy systems [16 17] Thus theknowledge of rheology and volume shrinkage behavior of theepoxy resin system is particularly necessary to have a correctcontrol of the processing mechanism and the subsequentengineering design

The very high specific surface area of nanoparticles how-ever causes the nanoparticles to attract each other due to vander Waals forces and to form agglomerates with dimensionsof several micrometers [6] It is reported that a considerableamount of improvement in mechanical properties can beachieved using very low amounts of nanofiller loadings [7 8]To extract maximum benefit from their high specific surfacenanoparticles have to be homogenously dispersed in thepolymer matrix to increase the effective interfacial surfacebetween the fillers and thematrixThemechanical propertiessignificantly depend on the dispersion of the particles inthe matrix This interfacial surface allows a good transfer ofthe applied load from the matrix to the nanoparticles Gooddispersion also results in a more uniform stress distributionand minimizes stress concentration which should increasethe general strength and modulus of the composites [1819] Nanoparticles are generally introduced into the polymermatrix by various techniques which include application ofhigh shear forces during mechanical stirring [7 20ndash22]pulsed ultrasound vibrations [23] and direct incorporationwith chemicalmethods [24 25]This avoids the agglomeratedstate

Nanoscaled TiO2has gained great interests in the last

decades because of its unique properties and good per-formance The TiO

2is extensively used in industry such

as additives for epoxies plastics and rubbers [6 26ndash30]Moreover TiO

2filled polymers arewell-known antimicrobial

materials [31ndash35] Since epoxy is a very common materialfor aerospace and automotive industry addition of TiO

2may

act as substitute for pollution treatment (in presence of UV

light TiO2generates hydroxyl radicals which can degrade

or oxidize the pollutants into more environmentally friendlyproducts) and disinfectant (photo catalytic degradation ofbacteria and grime) [35] which is a major industrial issueTiO2is well known for photo chemical degradation of toxic

chemicals UV shielding waste water purification and soforth Apart from that it is widely used in piezoelectric capac-itors solid oxide fuel cells electrode materials in lithiumbatteries energy converter in solar cells and so forth [36]

Very few studies have been reported on the epoxyTiO2

nanocomposites most of them are focused on the finalmechanical properties [37 38] However the effect of TiO

2

on cure rheology and volume shrinkage of epoxy systemshas never been investigated In this context a detailed studyin this topic is very important In this paper we presentan experimental investigation on the effect of mechanicallydispersed TiO

2on the network formation of an epoxyamine

system The effect of TiO2on the volume shrinkage was also

examined Finally we have investigated the thermomechani-cal properties of the cured epoxyTiO

2nanocomposites

2 Experimental Part21 Materials Used The epoxy resin diglycidyl ether ofbisphenol-A (DGEBA) (Lapox L-12 Atul Ltd India) wasused as the matrix material The amine hardener diaminodiphenyl sulfone (DDS) (Lapox K-10 Atul Ltd India) wasused as a cross-linker for the epoxy Nano-TiO

2 with size

around 100 nm was obtained from Riedel-de Haen (productcode 14027) Germany

22 Preparation of EpoxyTiO2Nanocomposites TiO

2nano-

particles were dispersed in DGEBA (epoxy) and mixed at180∘C using a high speed magnetic stirrer for two hours thena stoichiometric amount of DDS with an epoxy amine ratioof 2 1 was added as the curing agent and mixed well Thesolution was transferred to an open mold The compositeswere cured in the open mold at 180∘C for three hours andthen postcured at 200∘C for 2 hours Composites with TiO

2

contents of 0 1 5 and 10 g in epoxy-hardener mixture(100 g DGEBA + 35 g DDS) were prepared and the sampleswere named as neat epoxy 07 wt TiO

2 36 wt TiO

2 and

69 wt TiO2 respectively

For fourier transform infrared spectrometer (FTIR) dif-ferential scanning calorimetry (DSC) rheology and pressure-volume-temperature (PVT) observations the freshly pre-pared mixtures were immediately used or stored before usein a freezer at minus20∘C For other experiments the freshlyprepared mixtures were cured in the air oven at 180∘Cfor 3 h and then postcured at 200∘C for further 2 h Theresultant composites were then allowed to cool slowly toroom temperature

3 Characterization

31 Fourier Transform Infrared Spectroscopy In situ curingstudies were carried out using a fourier transform infrared-spectrometer EQUINOX 55 (Bruker Optik GmbH) A few




2atmosphere with an


(corr))















2composites were





3500

3367

1625

913

3000 1500 10000

02040608

1121416

Abso

rban

ce (a

u)

DDSEpoxy








3500 3000 1500

913

16253367

10000

2

4

6

8

10 Neat epoxy

Abso

rban

ce (a

u)

0 min15 min30 min

60 min120 min













3500 3000 1500 10000

2

4

6

8

10

33671625

913Abso

rban

ce (a

u)

0 min15 min30 min

60 min120 min

36 wt TiO2




0 20 40 60 80 100 1202

4

6

8

10

12

14

16

18

20

Time (min)


Inte

rgra

l abs

orba

nce a

t 913

cmminus1


0+ 119860

1exp(minus119909119905

1)) (119879 = 150∘C)


2containing



119910 = 119910

0+ 119860

1exp(minus 119909119905

1

) (1)


Specimen 119905

1(min) 119910

0119860

1119877

2



Samples Δ119867

119905(Jg) Δ119867

119905 (Corr) (Jg) 119879

119901(∘C)




1is


1 1198601 1199100 and 1198772 to assess the



2particles The



119901) and











100 150 200 250 300

0

005

01

Hea

t flow

(Wg

) exo

Neat epoxy

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

minus015

minus01

minus005






119910 = 119910

0+ 119860

1exp( 119909119905

1

) (2)




2follow a similar




2particles The cure




2




119889119909

119889119905

= 119860 exp (minus119864

119886

119877119879

)119891 (119909) (3)




lnint119909gel

0

119889119909

119891 (119909)

= ln119860 + ln (119905gel) minus (119864

119886

119877119879

) (4)


ln (119905gel) = constant +119864

119886

119877119879

(5)




900 950 1000 1050 1100 1150 1200 1250 13000

10000

20000

30000

40000

50000

60000

70000C

ompl

ex v

iscos

ity

Time (s)


36 wt TiO2

69 wt TiO2

180∘C

(a)

0 500 1000 1500 2000

0

2

4

6Neat epoxy

Crossover

Time (s)

0

20

40

60

80

100

120

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(b)

600 900 1200 1500

0

2

4

6Crossover

Time (s)

0

20

40

60

80

100

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(c)

1000 1500 2000 2500 3000 3500 4000 4500

150

155

160

165

170

175

180

Time (s)


Tem

pera

ture

(∘C)

07 wt TiO2

(d)

00022 000224 000228 000232 00023668

7

72

74

76

78

8

82

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

1T (Kminus1)

Int g

el(s

)

(e)



1exp(119909119905



2




0 2000 4000 6000 8000 10000

078

08

082

084

086

088

09

Spec

ific v

olum

e

Time (s)

(a)

(b)



2 particles



2epoxy 36 wtTiO

2epoxy and 69 wt

















2particles











2and 36 wt TiO

2due to







2 there were a







2filled com-










119892frozen






119892)


2dissipates


119892of the




5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)


2 and (d) 69 wt TiO

2





150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452





1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






2atmosphere with an


(corr))















2composites were





3500

3367

1625

913

3000 1500 10000

02040608

1121416

Abso

rban

ce (a

u)

DDSEpoxy








3500 3000 1500

913

16253367

10000

2

4

6

8

10 Neat epoxy

Abso

rban

ce (a

u)

0 min15 min30 min

60 min120 min













3500 3000 1500 10000

2

4

6

8

10

33671625

913Abso

rban

ce (a

u)

0 min15 min30 min

60 min120 min

36 wt TiO2




0 20 40 60 80 100 1202

4

6

8

10

12

14

16

18

20

Time (min)


Inte

rgra

l abs

orba

nce a

t 913

cmminus1


0+ 119860

1exp(minus119909119905

1)) (119879 = 150∘C)


2containing



119910 = 119910

0+ 119860

1exp(minus 119909119905

1

) (1)


Specimen 119905

1(min) 119910

0119860

1119877

2



Samples Δ119867

119905(Jg) Δ119867

119905 (Corr) (Jg) 119879

119901(∘C)




1is


1 1198601 1199100 and 1198772 to assess the



2particles The



119901) and











100 150 200 250 300

0

005

01

Hea

t flow

(Wg

) exo

Neat epoxy

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

minus015

minus01

minus005






119910 = 119910

0+ 119860

1exp( 119909119905

1

) (2)




2follow a similar




2particles The cure




2




119889119909

119889119905

= 119860 exp (minus119864

119886

119877119879

)119891 (119909) (3)




lnint119909gel

0

119889119909

119891 (119909)

= ln119860 + ln (119905gel) minus (119864

119886

119877119879

) (4)


ln (119905gel) = constant +119864

119886

119877119879

(5)




900 950 1000 1050 1100 1150 1200 1250 13000

10000

20000

30000

40000

50000

60000

70000C

ompl

ex v

iscos

ity

Time (s)


36 wt TiO2

69 wt TiO2

180∘C

(a)

0 500 1000 1500 2000

0

2

4

6Neat epoxy

Crossover

Time (s)

0

20

40

60

80

100

120

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(b)

600 900 1200 1500

0

2

4

6Crossover

Time (s)

0

20

40

60

80

100

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(c)

1000 1500 2000 2500 3000 3500 4000 4500

150

155

160

165

170

175

180

Time (s)


Tem

pera

ture

(∘C)

07 wt TiO2

(d)

00022 000224 000228 000232 00023668

7

72

74

76

78

8

82

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

1T (Kminus1)

Int g

el(s

)

(e)



1exp(119909119905



2




0 2000 4000 6000 8000 10000

078

08

082

084

086

088

09

Spec

ific v

olum

e

Time (s)

(a)

(b)



2 particles



2epoxy 36 wtTiO

2epoxy and 69 wt

















2particles











2and 36 wt TiO

2due to







2 there were a







2filled com-










119892frozen






119892)


2dissipates


119892of the




5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)


2 and (d) 69 wt TiO

2





150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452





1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




3500

3367

1625

913

3000 1500 10000

02040608

1121416

Abso

rban

ce (a

u)

DDSEpoxy








3500 3000 1500

913

16253367

10000

2

4

6

8

10 Neat epoxy

Abso

rban

ce (a

u)

0 min15 min30 min

60 min120 min













3500 3000 1500 10000

2

4

6

8

10

33671625

913Abso

rban

ce (a

u)

0 min15 min30 min

60 min120 min

36 wt TiO2




0 20 40 60 80 100 1202

4

6

8

10

12

14

16

18

20

Time (min)


Inte

rgra

l abs

orba

nce a

t 913

cmminus1


0+ 119860

1exp(minus119909119905

1)) (119879 = 150∘C)


2containing



119910 = 119910

0+ 119860

1exp(minus 119909119905

1

) (1)


Specimen 119905

1(min) 119910

0119860

1119877

2



Samples Δ119867

119905(Jg) Δ119867

119905 (Corr) (Jg) 119879

119901(∘C)




1is


1 1198601 1199100 and 1198772 to assess the



2particles The



119901) and











100 150 200 250 300

0

005

01

Hea

t flow

(Wg

) exo

Neat epoxy

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

minus015

minus01

minus005






119910 = 119910

0+ 119860

1exp( 119909119905

1

) (2)




2follow a similar




2particles The cure




2




119889119909

119889119905

= 119860 exp (minus119864

119886

119877119879

)119891 (119909) (3)




lnint119909gel

0

119889119909

119891 (119909)

= ln119860 + ln (119905gel) minus (119864

119886

119877119879

) (4)


ln (119905gel) = constant +119864

119886

119877119879

(5)




900 950 1000 1050 1100 1150 1200 1250 13000

10000

20000

30000

40000

50000

60000

70000C

ompl

ex v

iscos

ity

Time (s)


36 wt TiO2

69 wt TiO2

180∘C

(a)

0 500 1000 1500 2000

0

2

4

6Neat epoxy

Crossover

Time (s)

0

20

40

60

80

100

120

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(b)

600 900 1200 1500

0

2

4

6Crossover

Time (s)

0

20

40

60

80

100

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(c)

1000 1500 2000 2500 3000 3500 4000 4500

150

155

160

165

170

175

180

Time (s)


Tem

pera

ture

(∘C)

07 wt TiO2

(d)

00022 000224 000228 000232 00023668

7

72

74

76

78

8

82

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

1T (Kminus1)

Int g

el(s

)

(e)



1exp(119909119905



2




0 2000 4000 6000 8000 10000

078

08

082

084

086

088

09

Spec

ific v

olum

e

Time (s)

(a)

(b)



2 particles



2epoxy 36 wtTiO

2epoxy and 69 wt

















2particles











2and 36 wt TiO

2due to







2 there were a







2filled com-










119892frozen






119892)


2dissipates


119892of the




5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)


2 and (d) 69 wt TiO

2





150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452





1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




3500 3000 1500 10000

2

4

6

8

10

33671625

913Abso

rban

ce (a

u)

0 min15 min30 min

60 min120 min

36 wt TiO2




0 20 40 60 80 100 1202

4

6

8

10

12

14

16

18

20

Time (min)


Inte

rgra

l abs

orba

nce a

t 913

cmminus1


0+ 119860

1exp(minus119909119905

1)) (119879 = 150∘C)


2containing



119910 = 119910

0+ 119860

1exp(minus 119909119905

1

) (1)


Specimen 119905

1(min) 119910

0119860

1119877

2



Samples Δ119867

119905(Jg) Δ119867

119905 (Corr) (Jg) 119879

119901(∘C)




1is


1 1198601 1199100 and 1198772 to assess the



2particles The



119901) and











100 150 200 250 300

0

005

01

Hea

t flow

(Wg

) exo

Neat epoxy

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

minus015

minus01

minus005






119910 = 119910

0+ 119860

1exp( 119909119905

1

) (2)




2follow a similar




2particles The cure




2




119889119909

119889119905

= 119860 exp (minus119864

119886

119877119879

)119891 (119909) (3)




lnint119909gel

0

119889119909

119891 (119909)

= ln119860 + ln (119905gel) minus (119864

119886

119877119879

) (4)


ln (119905gel) = constant +119864

119886

119877119879

(5)




900 950 1000 1050 1100 1150 1200 1250 13000

10000

20000

30000

40000

50000

60000

70000C

ompl

ex v

iscos

ity

Time (s)


36 wt TiO2

69 wt TiO2

180∘C

(a)

0 500 1000 1500 2000

0

2

4

6Neat epoxy

Crossover

Time (s)

0

20

40

60

80

100

120

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(b)

600 900 1200 1500

0

2

4

6Crossover

Time (s)

0

20

40

60

80

100

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(c)

1000 1500 2000 2500 3000 3500 4000 4500

150

155

160

165

170

175

180

Time (s)


Tem

pera

ture

(∘C)

07 wt TiO2

(d)

00022 000224 000228 000232 00023668

7

72

74

76

78

8

82

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

1T (Kminus1)

Int g

el(s

)

(e)



1exp(119909119905



2




0 2000 4000 6000 8000 10000

078

08

082

084

086

088

09

Spec

ific v

olum

e

Time (s)

(a)

(b)



2 particles



2epoxy 36 wtTiO

2epoxy and 69 wt

















2particles











2and 36 wt TiO

2due to







2 there were a







2filled com-










119892frozen






119892)


2dissipates


119892of the




5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)


2 and (d) 69 wt TiO

2





150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452





1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




100 150 200 250 300

0

005

01

Hea

t flow

(Wg

) exo

Neat epoxy

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

minus015

minus01

minus005






119910 = 119910

0+ 119860

1exp( 119909119905

1

) (2)




2follow a similar




2particles The cure




2




119889119909

119889119905

= 119860 exp (minus119864

119886

119877119879

)119891 (119909) (3)




lnint119909gel

0

119889119909

119891 (119909)

= ln119860 + ln (119905gel) minus (119864

119886

119877119879

) (4)


ln (119905gel) = constant +119864

119886

119877119879

(5)




900 950 1000 1050 1100 1150 1200 1250 13000

10000

20000

30000

40000

50000

60000

70000C

ompl

ex v

iscos

ity

Time (s)


36 wt TiO2

69 wt TiO2

180∘C

(a)

0 500 1000 1500 2000

0

2

4

6Neat epoxy

Crossover

Time (s)

0

20

40

60

80

100

120

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(b)

600 900 1200 1500

0

2

4

6Crossover

Time (s)

0

20

40

60

80

100

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(c)

1000 1500 2000 2500 3000 3500 4000 4500

150

155

160

165

170

175

180

Time (s)


Tem

pera

ture

(∘C)

07 wt TiO2

(d)

00022 000224 000228 000232 00023668

7

72

74

76

78

8

82

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

1T (Kminus1)

Int g

el(s

)

(e)



1exp(119909119905



2




0 2000 4000 6000 8000 10000

078

08

082

084

086

088

09

Spec

ific v

olum

e

Time (s)

(a)

(b)



2 particles



2epoxy 36 wtTiO

2epoxy and 69 wt

















2particles











2and 36 wt TiO

2due to







2 there were a







2filled com-










119892frozen






119892)


2dissipates


119892of the




5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)


2 and (d) 69 wt TiO

2





150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452





1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




900 950 1000 1050 1100 1150 1200 1250 13000

10000

20000

30000

40000

50000

60000

70000C

ompl

ex v

iscos

ity

Time (s)


36 wt TiO2

69 wt TiO2

180∘C

(a)

0 500 1000 1500 2000

0

2

4

6Neat epoxy

Crossover

Time (s)

0

20

40

60

80

100

120

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(b)

600 900 1200 1500

0

2

4

6Crossover

Time (s)

0

20

40

60

80

100

minus2

logG998400

andG998400998400

(MPa

)

tan120575

(log G998400)(log G998400998400)

tan 120575

(c)

1000 1500 2000 2500 3000 3500 4000 4500

150

155

160

165

170

175

180

Time (s)


Tem

pera

ture

(∘C)

07 wt TiO2

(d)

00022 000224 000228 000232 00023668

7

72

74

76

78

8

82

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

1T (Kminus1)

Int g

el(s

)

(e)



1exp(119909119905



2




0 2000 4000 6000 8000 10000

078

08

082

084

086

088

09

Spec

ific v

olum

e

Time (s)

(a)

(b)



2 particles



2epoxy 36 wtTiO

2epoxy and 69 wt

















2particles











2and 36 wt TiO

2due to







2 there were a







2filled com-










119892frozen






119892)


2dissipates


119892of the




5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)


2 and (d) 69 wt TiO

2





150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452





1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





0 2000 4000 6000 8000 10000

078

08

082

084

086

088

09

Spec

ific v

olum

e

Time (s)

(a)

(b)



2 particles



2epoxy 36 wtTiO

2epoxy and 69 wt

















2particles











2and 36 wt TiO

2due to







2 there were a







2filled com-










119892frozen






119892)


2dissipates


119892of the




5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)


2 and (d) 69 wt TiO

2





150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452





1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





2and 36 wt TiO

2due to







2 there were a







2filled com-










119892frozen






119892)


2dissipates


119892of the




5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)


2 and (d) 69 wt TiO

2





150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452





1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




5120583m

(a)

10120583m

(b)

10120583m

(c)

10120583m

(d)


2 and (d) 69 wt TiO

2





150 4015 3580 3568 3721 4653 4853165 2266 2048 2139 2151 2476 2536180 1146 1000 1147 1097 1571 1452





1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




1000 nm

(a)

1000 nm

(b)

2000 nm

(c)

1000 nm

(d)


2 and (d) 69 wt TiO

2

350 400 450 500 550

20

40

60

80

100

Mas

s (

)

Neat

Temperature (∘C)

07 wt TiO2

36 wt TiO2

69 wt TiO2

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

360 390 420 450

0

Der

ivat

ive w

eigh

t

Temperature

minus2

minus15

minus05

minus1

(b)




Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





Temperature(∘C)


100 995 997 997 998200 982 989 989 991300 980 987 987 987400 931 942 941 935500 159 208 229 272600 134 183 202 248700 125 173 192 237

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 2500

05

1

15

2

Dim

ensio

n ch

ange

()

Temperature (∘C)










2particles










12

119887119889

(6)


119876 = 199 minus 041 (

119886

119887

) + 187(

119886

119887

)

2

minus 3848(

119886

119887

)

3

+ 5385(

119886

119887

)

4

(7)





2particles








Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






Tensile modulusGPa

Tensile elongation



Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200

25

3

35

4

minus50

Temperature (∘C)

logE998400

(a)

Neat07 wt TiO2

36 wt TiO2

69 wt TiO2

0 50 100 150 200 250

0

05

1

15

2

25

minus50

Temperature (∘C)

minus1

minus05

logE998400998400

(b)




FlexuralmodulusMPa

Flexuralelongation



2and the crack



3

35

4

45

5

55

6Epoxy composites

Filler content

03

04

05

06


Impa

ct en

ergy

(kJm

2)

KIC

KIC

(MN

m32

)

0 wtTiO2

36 wtTiO2

69 wtTiO2

07 wtTiO2




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a)

(b)

(c)

(d)


2 and (d)

69 wt TiO2









2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





2(Figure 14(d))


5 Conclusion



2nanofiller


















Acknowledgments


References
































2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials















2epoxy polymeric


















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Research Article Investigation of Cure Reaction, …downloads.hindawi.com/journals/jpol/2013/183463.pdfJournal of Polymers e cure kinetics and reaction mechanisms of various epoxy