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ISSN 0104-6632 Printed in Brazil
www.abeq.org.br/bjche
Vol. 33, No. 04, pp. 945 - 956, October - December, 2016 dx.doi.org/10.1590/0104-6632.20160334s20150172
*To whom correspondence should be addressed
Brazilian Journal of Chemical Engineering
EFFECT OF POLY (N- VINYPYRROLIDONE) ON THE NON-ISOTHERMAL CRYSTALLIZATION
KINETICS AND VISCOELASTIC PROPERTIES OF PVDF FILMS
A. Mashak1*, A. Ghaee2 and F. Ravari3
1Department of Novel Drug Delivery Systems, Iran Polymer and Petrochemical Institute,
P.O. Box: 14965/115, Tehran, Iran. *E-mail: [email protected]
2Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, P.O. Box: 143951374, Tehran, Iran.
3Department of Chemistry, Payame Noor University, Tehran 19395-4697, Iran.
(Submitted: March 15, 2015 ; Revised: August 24, 2015 ; Accepted: August 28, 2015)
Abstract - Poly(vinylidene fluoride) (PVDF) and PVDF blends with various molecular weights of poly (N- vinylpyrrolidone) (PVP) films were prepared in dimethyl formamide through the solution casting method. Non-isothermal melt crystallization studies of PVDF films were carried out by cooling the molten samples at different temperatures using differential scanning calorimetry (DSC). The obtained films have been characterized by dynamic mechanical thermal analysis (DMTA). Crystallization kinetics of PVDF films were successfully described by the Jeziorney, Mo and Ziabicki models. The Ozawa equation was found to be invalid for describing the crystallization kinetics. Kinetic parameters such as t1/2, Zc and F(T) indicated that the crystallization rate decreased for PVDF/PVP films as compared to neat PVDF films and was affected by the molecular weight of PVP. The results based on Ziabicki's model revealed that the addition of PVP decreased the ability of PVDF to crystallize under non-isothermal melt crystallization conditions. The activation energy was calculated through Friedman and advanced isoconversional methods. Results showed that the addition of PVP to PVDF films caused an increase in activation energy. By comparing DMTA results of PVDF/PVP blends with neat PVDF films, it could be concluded that blending PVDF with PVP caused an increase in the glass transition temperature (Tg) while the storage modulus was decreased. Keywords: Poly(vinylidene fluoride); Poly (N- vinylpyrrolidone); Crystallization kinetics; Non-isothermal crystallization; Differential scanning calorimetry.
INTRODUCTION
Polyvinylidene fluoride is popular in industrial applications as a semi-crystalline polymer due to favorable properties like good thermal stability, chemical resistance, high mechanical strength and ferro-electricity (Nasir et al., 2007; Sencadas et al., 2010). The crystalline structures of PVDF polymer, according to the chain conformation with trans or gauche linkages, are α, β and γ phases (Nasir et al.,
2007). The crystalline morphology and crystallinity of PVDF are of major importance in various applica-tions. However, the hydrophobic characteristic of PVDF is a limitation in some applications. For ex-ample, membrane fouling caused by hydrophobic interactions results in rapid water flux decline and high energy-consumption, especially when the wastewater contains natural organic matter (NOM), proteins and micro-organisms (Rajabzadeh et al., 2012).
946 A. Mashak, A. Ghaee and F. Ravari
Brazilian Journal of Chemical Engineering
Hydrophobic characteristics of polymers can be altered by polymer blending, that is more effective and widely used in comparison to chemical synthesis procedures (Ma et al., 2008; Li and Xu, 2012; Li et al. 2013). Studies showed that the crystalline phase of PVDF can be changed by blending with amor-phous polymers exhibiting physical interaction with PVDF. Therefore, it is necessary to investigate the crystallization kinetics for optimizing the process conditions and improving the structure-property cor-relation. The main focus has been on the crystalliza-tion behavior of PVDF and its blend in melt crystal-lization processes in the open literature (Lee and Ha, 1998; He et al., 2008; Zhong et al., 2011). Sencadas et al. (2010) studied the isothermal melt crystalliza-tion of PVDF at different crystallization tempera-tures. The Avrami parameters and the Hoffman-Weeks model were discussed to obtain the equilibrium melt-ing temperature. The crystallization and morphologi-cal behavior of PVDF/polyhydroxybutyrate blends were also studied by Liu et al. (2005). They de-scribed a phase diagram by calorimetric measure-ments and reported the Avrami exponent for pure PVDF, which has a value of approximately three. The miscibility behavior of poly(methyl methacry-late) and PVDF was investigated by Fan et al. (2007). They found that the Avrami exponent de-creases with rising crystallization temperature. Mancarella and Martuscelli (1977) also reported that the PVDF Avrami exponent variation was between 2.99 and 4.60 and that the half crystallization time was increased by an increase in crystallization tem-perature. Gradys et al. (2007) studied non-isothermal crystallization of PVDF at ultra high cooling rates. Their results indicated that pure β- phase of PVDF was obtained during the melt- crystallization process at cooling rates above 2000 K/s.
Although, there are some reports in the literature on the crystallization behavior of PVDF, less attention was paid to the non-isothermal crystallization kinet-ics of PVDF/PVP blends. In this study, the effect on PVDF crystallization of PVP with various molecular weights as an amorphous and water soluble polymer was investigated. The PVDF/PVP blend is a miscible system due to the compatibility of the two polymers (Chen and Hong, 2002; Ji et al., 2008; Freire et al., 2012). Dynamic mechanical thermal analysis (DMTA) was used to characterize the dynamic mechanical properties of PVDF films. The Jeziorney, Ozawa, Mo and Ziabicki kinetic models were applied to de-scribe the crystallization behavior of PVDF films. Furthermore, the activation energy of melt crystalliza-tion for sample films was determined from the Freid-man equation and advanced isoconversional method.
MATERIALS AND METHODS
Poly(vinylidene fluoride) (Mw = 530000 gmol-1) was purchased from Sigma-Aldrich (USA). Poly (N- vinylpyrrolidone) (PVP) (K 17, Mw 10,000 gmol-1 and 360000 gmol-1) was provided by Rahavard Tamin Chemical Co. (Iran). N, N-Dimethylformamide (DMF) was obtained from Sigma-Aldrich (USA) and used as solvent. All chemicals were used without further purification. Sample Preparation
PVDF films were prepared using the solvent cast-ing method. Poly(vinylidene fluoride) pellets were dissolved in DMF at 50 °C for 10 h and then poly(N-vinylpyrrolidone) was added at a PVDF: PVP weight ratio of 1:1. The PVDF solution was poured into a flat dish for solvent evaporation at room temperature within an interval of two weeks. The samples were dried further at 50 °C for 8 h to remove the solvent residues. The thicknesses of polymer films were about 150-200 µm. The samples were named neat PVDF, PVDF/PVP1 for PVP with low molecular weight and PVDF/PVP2 for PVP with high molecu-lar weight. Characterizations
The crystallization kinetics of PVDF polymer and the effects of PVP on its crystallization behavior were evaluated using a differential scanning calo-rimeter (DSC) (Polylabe 625, instrument, UK). The weights of all samples were ~5 mg. The samples were heated from room temperature to 200 °C with a 30 °C min-1 heating rate and held for 3 min to eliminate the previous thermal history. Subse-quently, the samples were cooled to 50 °C at prede-termined rates. The non-isothermal process included melt crystallization at different cooling rates: 2.5, 5, 10 and 20 °C min-1, while exothermal curves of heat flow were recorded as a function of tempera-ture and the experiments carried out under nitrogen atmosphere. FTIR spectra were obtained by a FTIR instrument (Bruker, model Equinox) in the 600–3500 cm-1 wave number range. Dynamic mechani-cal thermal analyses of the samples were carried out using a DMA, (Tritec 2000 machin) under the bending mode at a frequency of 0.1 Hz. The tem-perature range was from -100 to 100 °C at a rate of 5 °C min-1. The dried polymer films were cut into approximately 2.5×1×0.15 cm3 rectangles. The am-plitude was set to be within the linear viscoelastic regime.
N
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ESULTS AND
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zilian Journal of
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ting behaviorothermal cryxperimental dTable 1. FroDF/PVP1 anperature peahe heating prof crystalliz
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Fig. 1 are licrystallizat
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om pure PVain.
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VDF
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n Kinetics and Vi
No. 04, pp. 945 -
llization temhe results shores for the sa
It can be innize and forte. On the oton of the chaie cooling ratinitiate crystal., 2007). A
mperatures (f) of PVDF/Pat PVDF filmg higher mcrease more esence of PVg of the cryst
It can be sith an increaszation enthalpfluenced by Hc decreased
comparison lated to redud a lower deBased on t
ce on the cryplained by
VDF and PVons. The hyrbonyl group
VDF due to d the electhen and Hostricted move
different coolb and d) of n
iscoelastic Proper
956, October - D
peratures areowed that Tc
P
amples as thenferred that trm stable nuther hand, at in segments te; so, more tallization (B
According to(including thPVP samplems. The Tc
P olecular wethan for PV
VP in the PVtallization peeen that these in the coolpies of neat cooling rate
d significantlwith neat P
ction in the agree of perfehe results, Pystallinity ofinteraction
VP through hdrogen bondp of PVP anthe acidity o
tronegativity ong, 2002). ement of the
ling rates (a aeat PVDF an
erties of PVDF Fi
December, 2016
re shown forP shifted to le cooling ratethe PVDF muclei at a s
t high coolinof PVDF cosupercoolin
Bianchi et alo Fig. 1, the he values ofes are lower values for P
eight PVP (VDF/PVP1. InVDF film leaeaks. e values of Δling rate. ThPVDF filmse. However,ly for PVDFPVDF films.amount of crection of the PVP has a nf PVDF filmof function
hydrogen bonding occursnd the methyof PVDF hy
y of PVP oThis interac
e PVDF chain
and c) and thnd PVDF/PV
lms 9
r PVDF filmower tempere increased.
molecules reolower cooling rate the m
ould not follong was neede., 2014; Xioncrystallizatio
f Tcon, Tc
P anthan those
PVDF contai(PVDF/PVPn addition, thds to a wide
ΔHc decreasehe total crystas were slight, the value F/ PVP blen. This may brystals formecrystals.
negative inflms. This can bnal groups onding interas between thylene group ydrogen atomoxygen atomction suggesns.
hose of meltin
VP1 films.
947
ms. ra-
or-ng
mo-ow ed ng on nd of
in-2) he
en-
ed al-tly of ds be ed
lu-be of
ac-he of
ms ms sts
ng
94
Tfi
F
PtrPanatFb2anch
stcminTbthoH
FPP
48
Table 1: Chailms.
Sample PVDF
PVDF/PVP
PVDF/PVP
FTIR Spectr
For a bettePVDF and Proscopy was
PVDF and itsnd 890 cm-1 t 1160 cm-1
From the FTIe identified 012). The β nd the absorharacteristic
From Figtretching absm-1 in pure Pn PVDF/PVP
This shift towy the effect he carbonyl gf PVDF. The
Hong (2002).
Figure 2: FPVDF/PVP fPVDF/PVP1
aracteristic d
φ (°
P1
P2
roscopy
er understandPVP in PVDs used. Fig.s blends. Thare attributeassigned to
IR spectra, crby the absorphase is assirption bandsof α and γ p. 2 it can bsorption banPVP shifted P1 and PVDward higher f
of the hydrogroup of PVe same result
FT-IR specfilms: pure (c) and PVD
data of the n
C min-1)2.5
5 10 20 2.5
5 10 20 2.5
5 10 20
ding of interDF/PVP blend
2 shows she absorptioned to the C–Fo the C–C brystalline PVrption bandsigned at 828 s at 602 andphases, respecbe seen tha
nd of PVP asto 1662 cm-1
F/PVP2 filmfrequency caogen bond f
VP and the mt was reporte
ctra of neaPVP (a), n
DF/ PVP2 (d)
A. Mash
Brazilian Jou
non-isotherm
Tcon/°C
137.4 138
135.3 131
124.8 121.5
116 112.4
89 83 73 60
raction betweds, FTIR spspectra of nn bands at 13F vibration abond (Fig. 2VDF phases cs (Martin et
and 1063 cmd 1225 cm-1
ctively. at the carbossigned at 161 and 1691 c
ms, respectivean be explainformed betwemethylene groed by Chen a
at PVDF aeat PVDF ().
hak, A. Ghaee an
urnal of Chemica
mal crystall
Tc
P/°C134.8 134.7
132 126
120.4 115.7 109.6
105 102.2
96.9 93.9
85
een pec-neat 395 and 2a). can al.,
m-1, are
onyl 638
cm-1
ely. ned een oup and
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Dy
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al Engineering
ization beha
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132131126119114109100
9411111010
ynamic Mec
Viscoelasticeasured by tque. In dyn
DMTA), stifffect, which aes, are evaluaequency. Theonent in semobility of the
y the changemperature (Tpractice, Tg
aximum in thor loss mo
fect of PVP otermined by ing DMTA. ental molecuoups in the cg process (L13). Fig. 3 show
. temperaturVDF/PVP2 s50 to 100 °Cat an increase E' values os of PVDF cular weight ue to the lowat the presentermolecular
Lobo and Bd relaxation
avior for nea
°C .1 .2 .8 .6 .2 .6 .8 .1
13 11 08 04
hanical The
c properties he dynamic namic mechfness (E-moare two impoated as a fune presence ofmi-crystalline polymer che of the modTg) of the pol
determines the mechanic
odulus (E'') oon the amorp
evaluating dTwo relaxati
ular motions achain occurreobo and Bon
ws the storagre of neat amples in th
C at 0.1 Hz. Fse in temperaof polymeric films contaidecreased c
wer crystallinince of PVP dipole bond
Bonilla (2003process asso
at PVDF an
ΔTc 18.8 22.5 23.5 27.8 29.7 34.8 36.8
40 56.5 60.2 71.8 81.5
ermal Analy
of the matemechanical
hanical therodulus) and ortant viscoenction of temf a second po
ne polymers hains that cadulus and glymer (Badiathe temperatal damping poccurs. In t
phous regiondynamic proion processeand local mo
red during thnilla, 2003; O
ge modulus PVDF, PVD
he temperaturFrom Fig. 3a,ature caused films. The ining PVP wcompared winity. It could
in the filmding of PVDF3) have reporociated with
nd PVDF/PV
ΔHc (Jg-1) 36.49 36.41 36.11 35.95
34.1 30.3
33.84 32.5
30.92 27.28 26.64 14.67
ysis
erials could bthermal tec
rmal analysthe dampin
elastic propemperature anolymeric com
changes than be observeglass transitioa et al., 2014ture at whichparameter (tathis study, thn of PVDF woperty changes such as seotions of smahe PVDF heaOsinska et a
(E') and tanDF/PVP1 anre range of T, it is observe
d a decrease storage modwith high mith neat PVDbe considere
ms reduced thF chains. rted that the the crystallin
VP
be ch-sis ng er-nd m-he ed on 4). h a an he
was ges eg-all at-al.,
n δ nd T= ed in
du-mo-DF ed he
Tg ne
frantanvfoshcren
Fvsa C
otico(Δ Δ wthprthP
Effect
raction molend 86 °C, rean δ curve (Feat PVDF fialue is shifteor PVDF/PVhift of Tg to rease in the mnce of PVP, a
Figure 3: Thersus tempeamples.
Crystallizabi
A simple mf polymers aions was devordingly, theΔTc) with co
Δ = + ΔcT Pϕ
where ΔT0c is
he limit of zrocess sensithermodynam
P factor acco
of Poly (N- Viny
Braz
ecular motionespectively. TFig. 3b), whlm is -40 ºCed to higher
VP1 and PVDhigher temp
mobility of thas described
he tan δ (a)erature of ne
ility of PVD
method to eand their sensveloped by Ne variation inoling rate (φ
0Δ cT
s the degree zero coolingtivity factor.
mic driving founts for the
ypyrrolidone) on t
zilian Journal of
ns of PVDF The maximuhich is defin. For PVDF/temperature
DF/PVP2, resperatures conhe PVDF chapreviously.
) and storageat PVDF a
F
evaluate the sitivity to proNadkarni et n the degree oφ ) can be exp
of undercoolg rate and th
ΔT0c is asso
force for nuckinetic effe
the Non-Isotherm
Chemical Engine
occurred at um value of ned as the Tg/PVP films, ts (-8 and 35spectively). Tnfirmed the ains in the pr
ge modulus and PVDF/P
crystallizabiocessing conal. (1993). Aof undercoolpressed as:
ling requiredhe slope P iociated with
cleation andcts (Lorenzo
mal Crystallization
eering Vol. 33, N
-42 the
g of this
5 ºC The de-res-
(b)
PVP
lity ndi-Ac-ling
(1)
d in is a the the
o et
al.bequdethechthetiv
cotheblecrePVsugnuof PVThtio
FigPV Re
tiodetmeoth
X
whtem
rel
n Kinetics and Vi
No. 04, pp. 945 -
, 1999; Songthe differen
uent heating gree of supee ability of thanges in the e line of ΔTcvity factor.
Fig. 4 showoling rate. The intercepts ends. The reeased from 1VP1 and 53.ggests that
ucleation of PPVP. The va
VDF/PVP2> hese results son of PVDF i
gure 4: VariVDF and PVD
elative Cryst
The relativeon of the crytermined fromers by partiherms. X(t) is
( ) 0
0
∞
⎛⎜⎝=⎛⎜⎝
∫∫
T
TT
T
dHdX tdHd
here T0 and Tmperatures, r
For the nonlationship be
iscoelastic Proper
956, October - D
g et al., 201nce between scan (Table ercooling wihe polymer mthermal con
c vs. cooling
ws the plotshe values of to evaluate tesults show 18.8 for neat 9 for PVDFthe thermodPVDF is sigalues of the P
PVDF/PVPshow that PVin the blend f
ation of ΔTc DF/PVP film
tallinity of P
e degree of crystallization m the crystalial integratios defined as
⎞⎟⎠⎞⎟⎠
c
c
H dTdTdH dTdT
T∞ are the onrespectively. n-isothermal cetween cryst
erties of PVDF Fi
December, 2016
11). ΔTc was Tc
on and Tm1). The var
ith the coolmolecules to nditions. Thug rate is the
s of variationf ΔT0
c can be the crystallizthat the ΔT
t PVDF to 30F/PVP2. Sucdynamic drivgnificant afteP factor folloP1> neat
VP reduced tfilms.
c with coolinms.
PVDF
rystallinity (Xtemperature
llization exoton of crysta function of
nset and end crystallizatio
tallization tim
lms 9
consideredm in the subsriations of thing rate shorespond to th
us, the slopeprocess sens
n of ΔTc wiobtained frozability of thT0
c values i0.5 for PVDch an increaving force fer the additiowed the ordePVDF film
the crystalliz
ng rate for ne
X(t)) as a fune or time wtherms of poltallization ef temperature
(2
crystallizatio
on process, thme (t) and th
949
to se-he
ow he of si-
ith om he in-
DF/ ase for on er:
ms. za-
eat
nc-was ly-ex-e:
2)
on
he he
95
cofo
t
wzoticransainlacrh
FPin N M
thmpthw
50
orrespondingollows:
T Tφ
°−=
where φ is thontal temperime scale. Frystallinity wnd PVDF/Pame characteng rates dueater stage of rystallizationigher cooling
Figure 5: RePVDF (a) andng rates.
Non-Isotherm
Modified Avr
Several mehe non-isoth
mers. The Avrimary stagehe model, th
with crystalliz
g temperatur
he cooling rarature axis
Fig. 5 showswith crystalliVP films. Aeristic sigmoe to the sphef crystallizatin completiong rates.
elative crystad PVDF/PVP
mal Crystall
rami Model
ethods have hermal crystavrami equatioes of isotherhe relative czation time (
re (T) can b
ate (Ji et al., 2can be trans the variatiization time All these cuoidal shape aerulite impinion. It can bn, a shorter
allinity versuP1 (b) films a
lization Kin
(Jeziorney
been develoallization kion was used rmal kineticscrystallinity t) as follows
A. Mash
Brazilian Jou
be expressed
2008).The hosformed intoions of relatfor neat PV
urves have at various congement in e seen that,
r time requi
us time for nat various co
netics Analys
Equation)
oped to descrnetics of poto describe
s. According(X(t)) chan
s:
hak, A. Ghaee an
urnal of Chemica
d as
(3)
ori-o a tive
VDF the
ool-the for ires
neat ool-
sis
ribe oly-the
g to nges
X whan20
statheingof theby
log
whantal20shocostaextco
thereacanateshocrythecofilmfilmfilm
1/2t
kintalAsingtershofecdume
nd F. Ravari
al Engineering
( ) 1 exp(X t = −
here k and nd the Avram08). In actual co
antly during e parametersgs. Therefore
the crystalle cooling rat
y (Jeziorny, 1
logg tC
ZZφ
=
here Zc is thed Zt is the rallization proc15; Lang anown in Tabloling rate. T
ant of PVP ltent, in contoling rates. The crystal
e time (t) aaches 50%. n be obtainee non-isotherown in Tablystallization e higher coompletion timms. Moreovms are lowerms.
1/
2ln 2 n
k⎛ ⎞= ⎜ ⎟⎝ ⎠
Obviously, netic paramellization rate s discussed eg PVDF moractions withow that the cted more b
ue to more iner chains.
( )nkt−
n are the crymi exponent
onditions, thenon-isothermn and k hav
e, Jeziorney lization rate te. The modi978):
e modified crte constant ocess (Yu et
nd Zhang, 20e 2. Zc is in
The modifiedoaded PVDFtrast to that
llization halfat which the
t1/2 for non-ed from Equarmal crystalle 2. Generalprocesses. T
oling rates hmes for bo
ver, the valur in comparis
the data shoeters Zc and twas reducedarlier, this ef
olecular mobh PVP in the
crystallizatiy PVP withteractions of
rystallizationt, respective
e temperaturemal crystallive different p
considered constants b
ified equatio
rystallizationof the non-isoal., 2009; B
013). The vancreased by d crystallizaF films decrof neat PVD
f-time (t1/2), e extent of -isothermal ation 6 and lization ratesally, short t1/2The t1/2 valuehave shorter oth neat anues of t1/2 foson to those
ow that PVP t1/2. Thus, thd upon blendffect was caubility due toe molten station rate of Ph higher molf the PVDF a
(4
n rate constaely (Ji et a
e changes coization; hencphysical meathe correctio
by introducinn is expresse
(5
n rate constaothermal cry
Bahader et aalues of Zc aincreasing th
ation rate coeased to somDF, at variou
is defined crystallizatiocrystallizatioused to eval
s. The data a2 means fastes indicate thcrystallizatiod PVDF/PVor neat PVDof PVDF/PV
(6
influenced thhe PVDF cryding with PVused by reduo stronger ite. The resulPVDF was alecular weigand PVP pol
4)
ant al.,
on-ce, an-on ng ed
5)
ant ys-al., are he n-
me us
as on on lu-are ter hat on
VP DF VP
6)
he ys-VP. uc-in-lts af-ght ly-
O
appr1thvti
X
ln
wOnPF
Effect
Sample
Neat PVDF
PVDF/PVP1
PVDF/PVP2
Ozawa Meth
The Ozawpproaches foroposed by e978). This mhe non-isotheided into smion is express
( ) 1 expX t = −
(n ln 1 X⎡− −⎣
where K(T) aOzawa expon
ent dependsPlots of ln −⎡⎣
igure 6.
of Poly (N- Viny
Braz
Table 2: Cr
Φ (°Cmin-1)
2.5 5
10 20 2.5
5 10 20 2.5
5 10 20
hod
wa model is oor non-isotheextending themodel is basermal crysta
mall isothermsed as:
( )m
K Tφ
⎡ ⎤−⎢ ⎥⎣ ⎦
( )) ln (X t K⎤=⎦
and m are thnent, respecs on the dim
( )ln 1 ( )X t−
ypyrrolidone) on t
zilian Journal of
rystallizatio
Zc (°Cmin-1)
0.88 0.97 1.12 1.12 0.23 0.59 0.98 1.05 0.24 0.58 0.88 0.95
one of the mormal crystall
e Avrami Eqused on the aallization pro
mal steps. Th
( ) lnT m φ−
he cooling fuctively. Themension of c)⎤⎦ versus ln
the Non-Isotherm
Chemical Engine
n kinetic pa
t1/2(min)
0.98 0.91 0.58 0.35 2.99 1.93 0.93 0.66 4.01 2.69 1.56 1.25
ost used kinelization proceuation (Jeziorassumption tocess can be e Ozawa Eq
unction and Ozawa exp
crystal growφ are shown
mal Crystallization
eering Vol. 33, N
arameters of
Tmax (°C)
135.1 134.7 132.0 127.0 120.9 115.8 109.7 104.8 103.4
99.4 93.9 88.1
etic ess, rny, that di-
qua-
(7)
(8)
the po-
wth. n in
FigPV
corwisatkinthaingsec20 CoM
JezmaIn maleaQitheX(
n Kinetics and Vi
No. 04, pp. 945 -
f neat PVDF
(dX(t)/dt)max(s-1)
0.014 0.019 0.030 0.042 0.008 0.010 0.017 0.027 0.003 0.005 0.008 0.010
gure 6: TheVDF/PVP1 (b
It can be serrelations. Cith temperatutisfactory fornetics of PVDat the Ozawag the crystallcondary crys09).
ombined Avodel)
It is obvioziorny modiary stages oorder to find
al crystallizaagues suggesiu et al., 200e Avrami andt):
iscoelastic Proper
956, October - D
F and PVDF
Dφ (°C)
2.69 3.9
5.01 6.88 6.3
6.89 8.61 10.47 11.8 11.2 14.9 25.1
e Ozawa plob) films.
een that theshanges in slo
ure. Thus, thr the descripDF films. Soa model canlization kinestallization (
vrami and
ous that the ification couf non-isothe
d a method toation processsted a new m
00). This metd Ozawa Equ
erties of PVDF Fi
December, 2016
F/PVP films.
Gz,φ (°C min-1)
2.53 4.95 9.69
18.83 2.33 4.74 9.50
18.04 2.41 4.15 7.64
17.30
ots of neat P
se figures haopes indicate
he Ozawa mption of the ome authors
nnot be applietics of polym(Ozawa, 197
Ozawa Eq
Avrami anuld only desermal melt co describe ths exactly, Mmethod (Liuthod is the cuations at a
lms 9
Gz
1.01 0.99 0.96 0.94 0.93 0.94 0.95 0.90 0.96 0.83 0.76 0.86
PVDF (a) an
ave poor linee that m variethod was ncrystallizatiohave declare
ied for modemers that hav71; Yu. et a
quations (M
alysis and iscribe the prcrystallizatiohe non-isotheo and his co
u et al., 199combination given value
951
nd
ear ies not on ed el-ve
al.,
Mo
its ri-
on. er-ol-97; of of
95
ln
wcoddyothisPbli Tm
Fan
52
( )n ln F Tφ =
where ( )F T =ooling rate aefinite physiegree of cryield a linear f crystallinityhe Mo modesothermal pr
PVDF/PVP2 e calculated ines. The kin
Table 3: Thmodel.
Sample Neat PVDF
PVDF/PVP1
PVDF/PVP2
Figure 7: Plond PVDF/PV
) ln tα−
( ) / tK T Z= ⎡ ⎤⎣ ⎦and α is theical and pra
ystallinity, threlationship y, as shown iel was succesrocess of neafilms. The vfrom the slo
netic paramet
he kinetic p
X(t) % 20 40 50 80 20 40 50 80 20 40 50 80
ots of ln φ veVP1 (b) films
1m refers to
e ratio of n toactical meanihe plots of l
for a certainin Fig. 7. It cssful in descat PVDF, PVvalues of αope and the ters are listed
parameters
α 0.58 1.03 1.20 1.79 1.31 1.37 1.38 1.42 1.63 1.75 1.65 1.67
ersus ln t fors.
A. Mash
Brazilian Jou
the value of o m. F(T) haing. At a givnφ versus l
n relative degcan be seen tcribing the nVDF/PVP1 aα and F(T) c
intercept of d in Table 3.
from the M
F(T) 5.31 5.73 6.09 7.41 6.75 9.58 11.0
17.98 12
22.9 27.32
47.7
r neat PVDF
hak, A. Ghaee an
urnal of Chemica
(9)
the as a ven ln t
gree that
non-and can the
Mo
(a)
PVshocryingtheX(cryhigaccfoufilmpar An
thelizfunpofol dX
whexp
ZK
whlizTmcryisomeindtio
ZG
cryisocanfuneac
ZG
nd F. Ravari
al Engineering
The values VDF and 1.3ow that F(T)ystallinity. Og PVP reveae values achit) values. Siystallization gher F(T) vacordance wiund that F(Tms. This is rameters.
nalysis Base
Ziabicki deermal crystalzation progrenction (Ziablymers in Zillowing equa
( ) (ZX t K Tdt
=
here Kz(T), tpressed by:
,m( )Z ZT K=
here Tmax, Kzzation rate temax and the wystallization okinetic apprer crystallizadex), Gz ,wason (11) over t
(m
g
TZ Z
TK T
°
= ∫The Gz para
ystalline polyothermal cryn be replacenction of thch cooling ra
, (m
g
TZ
TdXϕ
°
= ∫
of α vary 1 to 1.7 for P) increased up
On the other hled higher Fieved for neaince F(T) ref
process, at alues for PVPith slower cT) values arealso in agre
d on Ziabick
veloped anollization kine
ess and crystaicki, 1996). abicki's mod
ation (first or
)[1 ( )]T X t−
he crystalliz
max exp 4ln⎡−⎢⎣
z,max and D aemperature,
width at half-rate functio
roximation, ation abilitys obtained bythe crystalliz
) 1.064T dT ≈
ameter expreymer to crys
ystallization sd in Equatio
he relative cate study as f
/ ) 1X dT dTϕ ≈
from 1.62 toPVDF/PVP fupon increasihand, PVDF
F(T) values aat PVDF filmflects the dit similar X(P loaded PVcrystallizatiore higher foreement with
ki Model
other approacetics related tallization ratCrystallizati
del can be derder kinetics)
zation rate fu
max2
( )n2 T TD−
are the maxthe crystalli
-height meason, respectivthe semi-cry
y (kinetic cy the integra
zation range:
,max4 .ZK D
esses the abistallize. In thstudies usin
on (12) with crystallinity, follows:
1.064( /dX dT
o 2.07 for nefilms. The dang the relativfilms contai
as compared ms at the samfficulty of tht) values, th
VDF films is on rates. It r PVDF/PVPh other kinet
ch for non-isto the crystate-temperatuion kinetics escribed by th):
(10
unction, can b
2 ⎤⎥⎦
(1
ximum crystaization rate sured from thvely. With thystalline polrystallizabiliation of Equ
(12
lity of a semhe case of nog DSC, KZ(the derivativ(dX/dT)φ, f
,max)T Dϕ ϕ (13
eat ata ve in-to
me he he in is
P2 tic
so-al-ure of he
0)
be
1)
al-at he he ly-ity ua-
2)
mi-n-T) ve for
3)
wcr(dinnGpliPTcrvPspPPta E
anvgetclothcoinu F
(M
ln
wrareEgbeqca
erPthin
Effect
where (dX/dTrystallizationdX/dT)φ funndex for an etic crystalli
Gz,α normalizaphol et al., ization kineti
PVP films baTmax decreasereased with alues of Gz
PVDF/PVP2 pectively. Th
PVP films shPVDF to crysallization con
Effective Act
Several mnd Friedmanation energyer, 1956; Vyat al., 2013)losely relaterder to calche effective onversional ntegral isocosed.
Friedman Eq
The FriedMa et al., 20
(
( )nX t
dX tdt
⎛ ⎞⎜ ⎟⎝ ⎠
where dX(t)/date as a funelative crysta
EX(t) the effeciven value oy plotting dXqual to -EX(tan be calcula
Fig. 8 illurgy as a fun
PVDF and PVhe results, tncreasing the
of Poly (N- Viny
Braz
T)φ,max, Dφ an rate, the w
nction and tarbitrary cooizability inde
zation with 2004). Tabl
ics parameterased on Ziabed, while (dX
increasing for neat PVfilms were
he reduction hows that PVstallize undenditions.
tivation Ene
methods suchn methods ary for the crysazovkin, 200). In fact, td to the relaulate approxactivation emethod of F
onversional m
quation
dman Equatio11; Friedman
)tan
tcons t=
dt is the innction of timallinity (X(t))ctive energy of X(t). A strX(t)/dt versust)/R. Thus, thated from the
ustrates plotsnction of relVP loaded PVthe activatioe relative cr
ypyrrolidone) on t
zilian Journal of
and Gz,φ are width at halthe kinetic oling rate. Tex, Gz, can φ (i.e., Gz e 2 summarirs of neat PVicki's model
dX/dT)φ,max, Dcooling rate
VDF and PV1.006, 0.933of the Gz va
VP decreasedr non-isothe
ergy
h as Kissingre used to evstallization p02; Friedmanthe activatioative crystallximately relienergy, the dFriedman anmethod of V
on is expresn, 1964):
( )
( )
X t
X t
ERT
−
nstantaneous me (t) for a
), R is the gabarrier of thraight line cs 1/TX(t). Thehe activatione slope of thes of effectivelative crystaVDF sampleon energy irystallinity,
the Non-Isotherm
Chemical Engine
the maximlf-height of crystallizabi
The Ziabicki be obtained = Gz,φ/φ) (Sizes the crys
VDF and PVD. The values
Dφ and Gz,φe. The averaVDF/PVP1 a3 and 0.835, alue for PVDd the abilityrmal melt cr
ger, Vyazovvaluate the aprocess (Kissn, 1964; Omron energy winity degree.iable valuesdifferential id the advanc
Vyazovkin w
ssed as follo
(1
crystallizatgiven value
as constant, ahe process focan be obtain slope of plon energy (EXe straight linee activation allinity for nes. Accordingincreased upsuggesting t
mal Crystallization
eering Vol. 33, N
mum the lity ki-by
Su-stal-DF/ s of in-
age and re-
DF/ y of rys-
vkin acti-sin-rani was . In
s of iso-ced
were
ows
14)
tion e of and or a ned
ot is EX(t))
e. en-
neat g to pon that
theincexpfrosloobvarPVcaupo
FigfunPV Ad
actto acctheThbe appfinmathenoenoplinprewasys
Φ
wh
aE
n Kinetics and Vi
No. 04, pp. 945 -
e crystallizatcrease in relpect that tra
om the equiliowed down served that tried in the
VDF/PVP1< used a delay lymer.
gure 8: Plonction of rel
VDF/PVP film
dvanced Isoc
It is notewotivation enerreliably pre
curacy of sue accuracy hus, errors in
minimized.proximation
nal plots yieations undene activation n-linear proergy by theed. An adv
near) was deesent study, as applied tostem using th
1
( )n n
ai j
E= ≠
=∑∑
here φ is th
a is the ac
iscoelastic Proper
956, October - D
tion becomeative crystalansmission oibrium melt tas crystallizthe calculatee followingPVDF/PVP2in the crysta
ts of effectivlative crystalms using the
conversiona
orthy that thrgy on relativdict the beh
uch predictioof calculatin
n computing tOne of the ss intentionalllding the aciably induceenergies. To
ocedure for e isoconversvanced isocoescribed by
a non-lineathe dynamic
he following
,
,
( , )( , )
na a i
a a ji
I E TI E T
φ
≠∑
he cooling rativation ene
erties of PVDF Fi
December, 2016
es more diffllinity. Indeeof the polymto the growt
zation proceeed activation g manner: 2 films, indicallization pro
ive activationllinity for ne
e Friedman e
al Method
he sole depeve crystallinihavior of a sons obviouslng the activthe activatiosources of thlly used to dectivation eneed an error ino resolve thcomputing
sional methoonversional Vyazovkin (
ar isoconversc DSC data
g equation:
)j
i
φφ
ate, T is theergy, i, j ar
lms 9
fficult with aed, one shoumer segmenh front will beds. It is alenergy valuneat PVDF
cating that PVocess of PVD
n energy as eat PVDF anquation.
endence of thity is sufficiesubstance. Thly depends ovation energ
on energy muhese errors aerive the lineergy. Approxn the values his problem,the activatio
od was devemethod (no(1997). In thsional methoof neat PVD
(15
e temperaturre the ordin
953
an uld nts be so
ues F< VP DF
a
nd
he ent he on gy. ust are ear xi-of a
on el-
on-he od
DF
5)
re,nal
95
nrapEInma
I
I
an
P
Eapthvob
FfuPm
ovnta
54
umbers of Dates. The acarticular con
aE at which tn Equation (
mined by the l., 1977) giv
0
( , )T
aI E Tα
= ∫
( ),aEI E T ⎛= ⎜
⎝
nd
( ) (expP x
x−
=
Each valuaE dependenc
pplied the shermal and nersional plotbtained from
Figure 9: Plounction of re
PVDF/PVP fimethod.
The non-if PVDF andarious coolineat PVDF, Pallization ab
DSC runs perctivation enenversion levthe ( )tΦ fun(12) the temp
Senum-Yanen as:
exp( )aE dTRT
α
( )aE P xR⎞⎟⎠
) 3
4 20x x
x x⎛− +⎜⎜ +⎝
ue of X(t) wace. The advansame compunon-isothermt trends in F
m the Friedm
ots of effectelative crystailms using th
CONCL
isothermal md its blends ng rates usin
PVDF/PVP bility due to
rformed at dergy can be
vel by findinnction has a mperature inte
ng approxima
T
2
3 218 88
120 24x x
x+ + ++ +
as minimizenced isoconvutational algomal DSC datFig. 9 are san method.
tive activatioallinity for n
he advanced i
LUSIONS
melt crystalliwith PVP w
ng DSC. As blends exhibi
the tendenc
A. Mash
Brazilian Jou
ifferent coole found at ang the valueminimum valegral was detation (Senum
(1
(1
9640 120x
⎞+⎟⎟+ ⎠
(
d to obtain ersional methorithm for ita. The isoc
similar to th
on energy aneat PVDF aisoconversio
ization kinetwere studiedcompared w
it reduced crcy of PVDF
hak, A. Ghaee an
urnal of Chemica
ling any
e of lue. ter-
m et
16)
17)
18)
the hod iso-on-
hose
as a and
onal
tics d at with rys-F to
inttwatoPVwafouTgJezdebe invKicalPVafftioPVFreThPVcon
Ba
Ba
Bi
Ch
Fa
Fre
nd F. Ravari
al Engineering
teract with ween the hydoms of the cVP on the gas also evaluund that PVD
values in cziorny, Mo scribe the crsuccessful.
valid for deinetic paraml models sh
VDF decreasfected by theon energies oVDF/PVP bleidman and
he higher vVDF/PVP blensistent with
adia, J. D., A., Ribes-Gmal Analystion of Polyand InterfaJyotishkumCo. KGaA,
ahader, A., Glization kincarbon nanliquid. Mac
anchi, O., Mrigaray, S. Melt crystameric silsestions. J. No
hen, N. P. andand compoPVP blend.
an, W., Zhenbehavior inand poly(vitopology ofPolym. Sci.
eire, E., BiaE. C., FortePVDF/PMMshear mixe(2012).
PVP througdrogen atomcarbonyl grouglass transitiuated by DMDF films cocomparison tand ZiabickrystallizationThe Ozawa
escribing theeters obtaine
howed that tsed in the pe molecular wof melt cryslends were
advanced value of thends comparh the lower ra
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