EFFECT OF CARBON BLACK AND SILICA FILLERS IN ELASTOMER BLENDS.pdf

8/11/2019 EFFECT OF CARBON BLACK AND SILICA FILLERS IN ELASTOMER BLENDS.pdf

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Effect of Carbon Black and Silica Fillers in Elastomer Blends

Yimin Zhang, S. Ge, B. Tang, T. Koga, M. H. Rafailovich,* , J . C. Sokolov, D. G. Peiffer, Z. Li, A. J . Dias, K. O. McElrath, M. Y.L in, S. K. Satija, S. G. Urquhart, #,& H. Ade, # and D. Nguyen $

Departm ent of M ateri als Science and E ngineeri ng, State Uni versi ty of N ew York at Stony Brook,Stony Br ook, N ew York 11794-2275; ExxonMobil Research and Engin eeri ng Company,Annan dale, New J ersey 08801; ExxonM obil Chemi cal Company, Polymer Science and B utyl

Technology Di visions, B aytown, Texas 77520; Center for Neutron Research, N ational In st i tute of Standar ds and Technology, Gaith ersburg, M arylan d 20899; Department of Physics,North Carolina State Universi ty, Raleigh, North Carolina 27695; and Brookhaven National Laboratory, Upton, New York 11973

Received January 30, 2001

ABSTRACT: The effects of carbon bla ck and pyr ogeneous silica fillers on th e interfa cial properties of ahomopolymer [polybutadiene, (PB)] and a terpolymer [brominated poly(isobutylene-co -p -methylstyrene),(BI MS)] ar e reported. Neutron reflectivity (NR) wa s used to st udy t he interfacial structure. The resultsare complemented by scanning transmission X-ray microscopy (STXM) and lateral force microscopy (LFM),wh ich were used to probe the morphology a nd surfa ce lat eral force. Sma ll-an gle neutron scatt ering (SANS)wa s used to chara cterize the size and surface properties of the filler a ggregates in elast omers. Our resultsshow that the interfacial behavior of P B/BIMS is more sensit ive to carbon black than to s i l ica. Theinterfacial broadening is significan tly slowed down w ith a ddition of merely CB ) 0.01 (volume fra ction)carbon black f i l lers . This volume level is much lower than that used in bulk rubbers (CB g 0.1).Py rogeneous silica ha s a less pronounced effect on th e interfacial cha racteristics. When both car bon andsilica are incorpora ted into t he P B layer, t he effect of carbon black is offset by silica fillers.

IntroductionFillers exist in a variety of systems such a s organic,

biological, biomimetic, and polymeric materials.1 In thelatter instance, the fil lers are intentionally added. Inpolymer syst ems, fillers not only reduce the cost of themat erial but a lso improve the mecha nical a nd dyna micproperties of the compounds. Carbon black and silicaar e the most w idely used fillers in rubber indust ry. Forexample, carbon black imparts strength and toughnessto elastomers, improves the rubbers resista nce to tear-

ing , abras ion , and f lex fa t igue, and a l so increasestra ction and dura bility.2 Silica a nd other t ypes of fillershave a weaker polymer- f il ler interact ion and areextensively used w here a high degree of reinforcementis not essential.3 Recently, silica w a s found to improvethe processability of rubbers and was used as partialor even complete replacement for carbon black fillers.4

Consequently, a significant research effort was dedi-cat ed to explain th e complex reinforcing effects of fillersin rubber ma trices. Although t here a re disagr eementsin certa in a reas, i t is well accepted th at the reinforce-ment effects are due to molecular interactions of therubber and filler particles.5 P revious s tudies of filler-elastomer syst ems ha ve mostly been conducted on bulkrubber with a large volume fraction ( g 0.1) of fillerparticles. For example, rheological data on filled com-pounds of va rying filler volume fra ction, such a s Mooneyviscosity, minimum t orque of curometer mea surement,

and modulus, indicate that the reinforcing effect is nota pparent unless the car bon bla ck filler volume fractionis more than 0.05.

In many applications, different types of unfilled andfilled rubber compounds ar e blended. The ultimateproperties of these blends are directly related to theinterfacial s t ructure and propert ies . Control of theinterfacial propert ies , such as adhesion, can have adrama tic impact on the performance of t he blend.However, quantification of surface and interface proper-

t ies is less explored due to the complexi ty of thepolymer- filler ma trix. P reviously, severa l groups ha veshown that the dynamics of polymers near an attractiveinterface can be dra stically reduced.6- 9 In a f il ler-polymer composite, especially in polymer nanocompos-ites, there is a large excess of interfacial a rea creat ed.Hence, it is important to determine how the interfacialinteractions between the filler and polymers affect thedynamics of interface formation and rheological proper-ties.

The two elastomers studied in this work are poly-butadiene (PB) and brominated poly(isobutylene-co -p -methylstyrene) (BIMS), a synthetic terpolymer of iso-butylene (IB), p -methylstyrene (PMS), and p -bromo-

methylstyrene (BrPMS). The molecular structures ofBI MS an d its unbrominated ana logue copolymer poly-(isobutylene-co -p -methylstyrene) (IMS) are shown inFigure 1. Isobutylene-based elastomers a re w idely usedin the automotive industry because these mater ia lspossess low permeability to gases, and one can controlthe mechanical properties by var ying the level of IB an dPMS as well as filler content and cross-link density.10Consequently, in standard rubber tires, both the hardsidewall and the sof ter inner l iner can be made ofcarbon-reinforced B IMS blended with butyl a nd na tura lrubber. 11

State University of New York at Stony Brook. ExxonMobil Research a nd Engineering Company. ExxonMobil Chemical Company. National In stitute of Sta ndards and Technology.# North Carolina State University.$ Brookhaven National Laboratory.& Current address : Depar tment of Chemistry, U niversi ty of

Saskatchewan, Sa skatoon, SK S7N 5C9, Canada .* To wh om correspondence should be a ddressed.

7056 M acromolecul es 2001, 34 , 7056 - 7065

10.1021/ma 010183p CCC: $20.00 2001 American C hemical SocietyP ubl ish ed on Web 08/31/2001


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In this paper w e describe neutron reflectivity (NR)measurements to determine the effects of low carbonblack and silica filler fraction on the interface formationbetw een B IMS a nd P B. S mall-an gle neutron scat tering(SANS) is used to cha ra cterize the doma in size of filleraggrega tes in elastomer- filler mat rixes. La teral forcemicroscopy (LFM) a nd scanning tra nsmission X-ra ymicroscopy (STXM) a re us ed t o determine t he sur facerheological properties in the presence of fillers.

Experimental SectionMaterials. The chara cter is t ic data of several grades of

BIMS terpolymer and the unbrominated analogue copolymer(IMS), provided by ExxonMobil Chemical Corp. (Baytown, TX),are listed in Table 1. B oth polymers a re elastomeric in na ture

wi th a low T g (- 50 C).10

The polydispersity of these com-mercial polymers is in t he ra nge 2.5- 2.8. Monodisperse dPB(M n ) 223 000, M w /M n < 1.03) wa s purchased from PolymerSource Inc., Montreal, Canada. Three types of carbon black,N330, N351, a nd N660, w ere supplied by Carbot Corp. ,B illerica , MA, wit h prima ry pa rticle sizes of 290, 290, and 500, respectively. Silica pa rticles w ere pyrogenous silica Aerosil300, with primary particle size of 90 and specific surfacearea of 295 m2/g. The density of carbon black an d silica are1.85 a nd 2.2 g/cm 3, which was used for conversion from weightfraction to volume fraction (). Deta iled cha ra cteristics of thesefillers can be found elsewhere.12,13 Hereafter, w e use C B a ndSF to describe the volume fraction of carbon black a nd silicafillers, respectively.

Small-Angle Neuron Scattering (SANS). Prescribedamounts of carbon black and polymer, as listed in Table 2,

were weighted an d mixed in a B rabender at 100 rpm and 150 C for 10 min. Approximat ely 0.5 g of the mixture w as placedin a sam ple holder. The final shape of the sa mple is circularwith a thickness of 1 mm with the flat faces perpendicular tothe neutron beam. This path length w as chosen to ensure thebest ba lance between the scat tering intensity a nd a ttenuat ion.Otherwise, the samples are considered isotropic w ith nopreferred orienta tion.

To probe an extended ra nge of the momentum tra nsfer, orscattering w avevector, q , a combination of conventional SANSand ul trasmall-angle neutron scat t er ing (US ANS) measure-ments w ere performed. The conventional SANS w as performedat the Center for Neutron Research (NCNR), the NationalInstitute of Standards and Technology (NIST), in Gaithers-burg, MD. A neutron wa velength of 6 was used, with twocoll imation configurat ions. One ha s a sample- detector dis-tance of 2.9 m, measuring the high q ra nge of 0.03- 0.2 - 1.The other has the sample - detector distance set at 15.2 m,measuring a m edium q range from 0.003 to 0.04 - 1. S tandardsam ples were used to calibra te the instrument so all intensitymeasured w as of the a bsolute scale of scattering cross sectionper unit volume (unit of cm- 1). The USANS experiments wereperformed at Oak Ridge National Laboratory, in Oak Ridge,TN. A B onse-Ha rt setup w ith t wo triple bounce Si cryst als w asused as monochromat or and a nalyzer for the ultra high angularresolution obta ined.14 With the neutron wavelength set at 2.59, the instrument produces ultra low q ra nge dat a of 0.0001-0.002 - 1. Because USANS data were taken with slit geometryan d conventiona l SANS ha s pinhole geometry, a deconvolutionwa s done for the USANS dat a before all thr ee sets of the dat afrom the sam e sample were merged, producing a wide q rangefrom 0.0001 to 0.2 - 1.

Neutron Reflectometry (NR). A detailed procedure ofsample preparation was described in a previous article.15 Herewe only brief ly describe th is procedure. The NR samplesconsist of tw o polymer layers. The first la yer of dPB wa s spin-coated on silicon substrates from a toluene solution at 2500rpm. To prepare analogue dPB layers with carbon black orhydrophobic silica fillers, the filler wa s w eighted an d dissolvedin a small amount of toluene by sonication, and then the filler-containing solution was thoroughly mixed with a prescribedamount of the dPB solution before spin-coating. The siliconwa fer substrate w as 1 cm th ick and 7.6 cm in diameter a ndwa s etched by HF to ensure a hydrophobic surface beforein t roducing the f ir s t l ayer of dPB. This l ayer w as thenpreannealed at 120 C for 1 h in a vacuum of 10- 3 Torr to relaxany s t ra ins a nd remove the solvent in t roduced f rom thespinning process. The second la yer w as prepared by m olding5 g of B IMS (or carbon-filled elast omer of prescribed composi-

tion) into a disk-shaped piece, which has a thickness of 1 mmand a diameter of 7.6 cm. The two layers were sandwichedjust prior to the NR experiment. To meas ure th e interdiffusionbetween the t wo polymer layers, the bilayer sa mple, confinedin a special press, wa s placed in a n oven a nd a nnealed in avacuum of 10- 3 Torr at 150 C for prescribed times. Afteran nealing, the sa mples were quickly quenched in a ir to roomtemperature w ithin 5 min.

The sa ndwiched wa fers were then mounted on the horizon-ta l sample ta ble at th e NIST neutron reflection spectrometer.The NR geometry is shown in Figure 2. The neutron beamenters thr ough the 1 cm th ick silicon w afer in t he Q in direction,and then i t i s ref lected f rom the BIMS/dPB and s i li coninterfaces and is detected again in the Q out direction. Thetechnique of NR and i ts data analysis were previously dis-cussed in a review by Russell.16 In this work, there are seven

Figure1. Molecular structures of the BI MS terpolymers a ndIMS copolymer.

Table 1. Isobutylene, p -Methylstyrene,p -Bromomethylstyrene, Number-Averaged MolecularWeight ( M n ), and Neutron Scattering Length Density(SLD) of BIMS and IMS Polymers Used in This Study

polymerP IB

(mol %)P MS

(mol %)BrPMS(mol %)

M n(kg /mol)

SLD(10 - 6 - 2)

B IMS-1 93 6.2 0.75 189 - 0.21B IMS-2 94 5.2 0.85 200 - 0.23B IMS-3 96 2.5 1.2 200 - 0.27IMS 94 6.1 0 200 - 0.23

Table 2. Composition and Aggregate Size of SANSSamples

polymer vol f r act ion () of filler R g of aggrega tes ()

IMS CB ) 0.025 1200IMS CB ) 0.005 1200BIMS-2 CB ) 0.025 1100BIMS-2 CB ) 0.005 1100BIMS-3 SF ) 0.025 > 10000

M acromolecul es, Vol. 34, N o. 20, 2001 Fil lers in Elastomer Ba nds 7057


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bilayer samples, the compositions of which are listed in Table3. We will hereafter m ention these bilayers a s sa mples A- G .

Scanning Transmission X-ray Microscopy (STXM). TheSTXM samples were prepared by spin-coating films of ap-proximately 1200 thick on Si3N 4 membranes. The Si3N 4membrane provides an X-ray tra nsparent substra te to supportthe thin polymer layers for X-ray microscopy investigation. Theresulta nt tw o films (50/50 blend of dP B /B IMS -1 a nd 50/50blend of P B/BI MS-1 with fillers C B ) 0.025) w ere a nnealedin a vacuum oven for 18 h a t 150 C. The STXM experimentwa s performed on beamline X1A at th e Nationa l SynchrotronLight Source (NSLS) a t Brookhaven Na tional Laboratory(B NL). The S TXM m icroscope uses diffr a ctive focusing optics(a Fresnel zone plate) to produce a microprobe w ith a 35- 50nm diam eter. An ima ge is formed by measuring the tr ansm it-ted X-ra y signa l as a thin sa mple section (typically 100 nmthick) is raster scanned through the focus of the zone plate.The X-ray energy used for imaging can be chosen to correspondto discrete electronic transitions in the material, such as theC 1s f *Cd C t ra nsi t ion a ssociated w ith Cd C double bonds,which occurs at 285 eV in most materials . This X-rayabsorption can be used to form a chemical ima ge contra st. Thismicroscope has been described by J acobsen et al.,17 and theapplicat ions to polymers w ere recently reviewed.18

Lateral ForceMicroscopy (LFM). Silicon wafers (300 mthick, orientation 100, Wafer World Inc., West Palm Beach,FL) were cut into 2 cm 2 cm pieces and cleaned by CrO3/H 2SO4 solution followed by dilute HF to remove any organicand the oxide layer. The initially sta tionary w afer w as floodedwit h toluene conta ining 14 mg/mL dP B an d carbon black N330

of CB ) 0 - 0.15 and then quickly (within 2 s) accelerated to2500 rpm for 30 s . The resu ltan t f ilms, wi th th icknessapproxima tely 690 , w ere measured w ith a Rudolph AutoELellipsometer. The reference polystyrene (P S, M n ) 280K,Polymer S ource Inc.) layers w ere first spin-coat ed onto glasssubstrates. After being floated off the glass substrates and ontothe surface of a distilled wa ter bat h, the P S films w ere pickedup by th e silicon wa fers precoated w ith ca rbon-black-filled dP Blayers. The PS film is 230 thick and only partially coversthe precoat ed dP B surface. Subsequently, the double-layersamples were dried in air for 24 h. The thin films with silicafillers w ere prepared by a similar procedure.

The topography a nd la te ra l force o f these dPB layersconta ining different CB a nd SF were imaged with a DI3000AFM (Nanoscope IIIa , D igital Instruments , Co. , Ltd. , Sa ntaBa rbara , CA). The AFM w as operated in th e contact mode, at

room temperature, in a sealed glovebox purged with drynitrogen gas, using a silicon nitride tip on a cantilever with abending spring constan t of 0.02- 0.1 N/m. The ima ge force w a srepulsive, approximately 25 nN. LF M images the lateraldeflections of t he can tilever from forces on the cantileverparal lel to the plane of the sample surface. To obtain themaximum LFM signal , the cant i lever wa s scanned along thedirection perpendicular to its axis. The lateral force measure-ment invest igates t he fr ict ion variat ion of the elastomersurfaces. Since the true value of cantilever spring constant isunknown, the relative lateral force was estimated by using areference PS layer covered on t he sa mple surface.

Results and Discussion

Small-AngleNeutron Scattering. SANS measuresthe micromorphology of a bulk sa mple. We combineconventional SANS and USANS to probe length scalesfrom 10 to microns. Therefore, the purpose of SANSexperiments w a s to observe wheth er the filler pa rt iclesa re well d ispersed in the e las tomer mat r ix a nd tochara cterize the size of filler part icles or a ggrega tes. Inaddition, interfacial properties between the particlesand their surrounding polymer chains can also beprobed with SANS.

The result of tw o slightly different systems, N330/B IMS -2 and N660/IMS , is shown in Figur e 3 a nd Figu re4. In the figures we plot the scatt ering intensity I a s afunction of q . The two curves in each figure representtw o different ca rbon/elas tomer volume fra ctions (uppercurves, CB ) 0.025; lower curves, CB ) 0.005) to testconcentra tion effects, if a ny. The intensity for bothsamples scales with CB (actua l scaling not shown),

Figure 2. Typical geometry of specular neutron reflectivitysetup. A thin dPB film is spun-cast onto a 1 cm thick Si wafer.

A 1 mm t hick disk of BIMS is placed on top of the dPB layer.The neutron beam enters through the Si wafer in the Q indirection. The beam is reflected from the dP B /B IMS interfa ceand is detected in the Q out direction.

Table 3. Structure and Composition of Seven BilayerSamples for NR Experiment

lower dPB layertop elastomer Layersample

designationthickness

() f iller vol ela s tom er f iller v ol

A 500 0 B IMS-1 0B 450 CB ) 0. 003 B I M S-1 0C 380 CB ) 0. 005 B I M S-1 0D 380 CB ) 0. 025 B I M S-1 0E 580 0 IMS CB ) 0.025F 600 SF ) 0. 005 B I M S-1 0G 600 0 B IMS-2 CB ) S F ) 0.01

Figure 3. A log- log plot of scat t er ing intensity (I ) a s afunction of q for IMS blended w ith ca rbon N330 of CB ) 0.025(upper curve) and CB ) 0.005 (lower curve).

Figure 4. A log- log plot of scat tering intensity a s a functionof q for BIMS-2 blended with carbon N660 of CB ) 0.025(upper curve) and CB ) 0.005 (lower curve).

7058 Zhang et al . M acromolecul es, Vol. 34, N o. 20, 2001


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indica ting little concentra tion effects. The combina tionof SANS and USANS data from q ) 0.0003 t o 0.2 - 1cover a very broad q range for the carbon black ag-grega tes. A roll-over t owa rd the low q end can be seenfrom the curves, a l lowing G uinier f i ts of the data toob ta in the rad ius of gyra t ion of the ind iv idua l ag-gregates. Guinier s equation is as follows:19

where I is the scat tered intensity, I 0 is a q -independentquan t i ty, and R g i s the average rad ius o f gyra t ion .Therefore, if ln(I ) is plotted vs q 2 in the ultra low q range(q < 0.001 - 1), the slope of the linear fit equals - 1/3R g2. It should be noted tha t th is argum ent is valid onlyif there is a linear fit between the two quantities, andqR g is smaller tha n or close to 1. Using t his method, weobtained the R g values of the two s l ight ly differentcarbon/elast omer systems (1100 a nd 1200 ), wh ichwere a lso listed in Ta ble 2. On th e basis of the prima rypar t icle s i ze of 290 and 500 , we est imate tha tapproximately 10- 50 primary pa rticles form a n a verageaggregate in these systems.

Also for the carbon black samples, a power law behavior can be seen at high q ra nge. Fits to the Porodform20

reveal t ha t t he exponent for the power la w is R ) 4.03( 0.05, suggesting rather sharp surfaces of the particles.

In contrast, the low-q da ta for silica /B IMS -3 syst em(Figure 5) do not s how a roll-over sh ape in t he G uinierregion, even at the USANS range approaching q

min )

0.0001 - 1 or a length scale of 1/q ) 1 m. Therefore,the s ize of the aggregates or agglomerates is l ikelylarger than several microns. This is in agreement withthe l iterature that s i lica f il lers ha ve much s t rongerinterpar ticle interactions.21 The broad shoulder peakwhich corresponds to the form factor of the primaryparticles a ppeared a round q ) 0.01 - 1 . On the basisof the spherical model th at ta kes the polydispersity ofthe par t icles into account , the s ize of the pr imaryparticle wa s estimated t o be 90 with polydispersityof 30%, w hich is in good a greement with the man u-facturer s specificat ion. In addition, th e reasonablestraight-line shape of the curve at low q suggests afractal structure within the aggregates or agglomerates,

with a fracta l dimension of d f ) 2.41. From the fittingat larger q , the curve bend to another power law , wherethe sa me Porod exponent is measu red,R ) 4.05 ( 0.02.As expected, both ty pes of the filler par ticles do not fusewith the surrounding elastomers.

Neutron Reflectivity. All of the r eflectivit y pr ofileswere plotted as log R vs Qz , where Qz ) (4 / ) sin ,a nd Qz , , and ar e the incident neutron wa ve vector,neutron w avelength, and incident angle, respectively.For each sample, the reflectivity curves for differentanneal ing t imes were ver t ical ly shif ted in the samefigure for clarity and comparison purposes.

Figure 6 shows the reflectivity profiles (R ) obtainedfor sample A after annealing at 150 C for 0 (i .e. , noannealing), 30, 60, and 150 min. From the reflectivitycurve for the unannealed sample w e can see w ell -defined K iessig oscillations, which indicate tha t theinterface between the dPB layer and the BIMS-1 issharp. The curve for the unannealed sample is fit by asingle-layer model of dPB with an error function inter-face with t he B IMS-1, which is a ssumed to be an infinitemedium. The dP B layer is w ell fit ted with a thicknessof 494 an d a dPB /B IMS interfacial width w ) 30 ,as shown in th e inset. After a nnealing for 30 min, theamplitude of the oscillations decreases, indicating thatthe interfa ce is becoming more diffuse. The concentra -tion profile of diffused dPB layer can be fit ted by anasymmetric model described elsewhere.15 The dPB/BI MS interface after 30 min of annea ling wa s found tobe 260 . Further anneal ing for a total of 150 minyielded a profile with an interfacial width of 340 ,which is in agreement with the equil ibr ium valuemeasured previously.15 The remaining low-frequencyoscillat ion is due to a monolay er of dP B a dsorbed to thehydrophobic silicon surface, which is discussed else-where.15

Figure 7 shows the reflectivity profiles for a samplewh ere carbon black of CB ) 0.003 wa s incorpora ted inthe lower dPB layer (sample B). From the figure we ca nsee that the interdiffusion has already begun to slow even though the carbon black concentration is verysmall.22 The best fits to the data are shown in the insetwhere we can see that the interface gradua lly broadens

Figure5. A log- log plot of scattering int ensity a s a functionof q for B IMS-3 blended w ith hydrophilic silica S F ) 0.005.At low q region rollover was not found. Dotted line is thebest fit of spherical model to scat tering profiles. The dia meter,R , and polydispersity, ( R)/ R , of the particles are 90 and0.3, respectively.

I ) I 0e- (1/3) q 2R g2 (if qR g e 1)

I ) A q -R (if qR g . 1)

Figure 6. Neutron reflectivity data for different annealingt imes of the bi layer sa mple with a lower la yer (dPB ) 500 thick a nd an overlayer (BI MS-1) 1 mm thick. The solid linesrepresent the best fits t o the experimenta l dat a. The dat a setsare offset for clarity . The inset shows best-fit profiles of dP Bvolume fract ion as a funct ion of dis tance from t he s i l iconsurface.



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from 50 for the unannealed sample to a maximum of228 after an nealing for 150 min. From Figure 8 wecan see that when CB is increased t o 0.005 in the dP Blayer (sam ple C), the interdiffusion is dra stically slowed.The Kiessig oscillations in the specular reflectivity ar eha rdly damped even aft er annea ling at 150 bcC for 150min. The volume profile tha t best fits t he da ta is shownin the inset where we see that the interface broadensonly from 30 to 50 a fter 150 min of a nnea ling. WhenCB is increa sed to 0.025 (sa mple D), interdiffusion wa snot observed at all. From the reflectivity data shown inFigure 9 we can see that the Kiessig oscillations are infact s ligh t ly sharper in the annea led sample. Theprofiles used to fit the da ta ar e shown in t he inset w herewe can see that the interface sharpens from 30 to 20 after annealing for 150 min. To rule out confinementeffects in the thin dPB film or other interference fromthe proximity of the silicon interface, we also mixedcarbon black particles into a n IMS (i.e. , the unbromi-

na ted ana logue o f B IMS) mat r ix us ing a Brabendermixer. In Figure 10 we show the reflectivity data forsample E which corresponds to an unfilled lower layerof dPB with a thickness of 580 sandw iched with a 1mm th ick slab of IMS with

CB ) 0.025. Fr om the figur e

we can see tha t t he Kiessig fringes persist a fter an neal-ing for 150 min in this sa mple as w ell. Fr om the profilesthat are used to f i t the data (shown in the inset) wecan see tha t only a small a mount of interdiffusionoccurs. The interfa ce shows a gra dua l broa dening from22 to 95 . Most of the broa dening is due t o a long t a ilin t he fitt ed volume fraction profiles, probably indu cedby diffusion of the low molecula r w eight chains, a s IMSand BIMS both have a relatively large polydispersityof 2.5- 2.7. Hence, the addition of carbon black drasti-cally slows down the interdiffusion regardless of thepolymer matrix in which it is added. The quantitiesadded are re la t ively small compared t o the volumesusual ly added for commercial applicat ions, such as

Figure 7. Neutron reflectivity data for different annealingtimes of the bilayer sample with a lower layer (dPB filled withcarbon black N351 of CB ) 0.003) 450 thick and an overlay er(B IMS-1) 1 mm thick. The solid lines represent the best fitsto the experimental data. The data sets are offset for clarity.The inset shows best-fit profiles of dP B volume fra ction a s afunction of distan ce from the silicon surfa ce.

Figure 8. Neutron reflectivity data for different annealingtimes of the bilayer sample with a lower layer (dPB filled withcarbon black N351 of CB ) 0.005) 380 thick and an overlay er(B IMS-1) 1 mm thick. The solid lines represent the best fitsto the experimental data. The data sets are offset for clarity.The inset shows best-fit profiles of dP B volume fra ction a s afunction of distan ce from the silicon surfa ce.

Figure 9. Neutron reflectivity data for different annealingtimes of the bilayer sample with a lower layer (dP B filled withcarbon bla ck N351 of CB ) 0.025) 380 thick and an overlay er(BI MS-1) 1 mm thick. The solid lines represent the best fitsto the experimental data. The data sets are offset for clarity.The inset sh ows best-fit profiles of dP B volume fra ction a s afunction of distan ce from the silicon surface.

Figure 10. Neutron reflectivity data for different annealingt imes of the bi layer sa mple with a lower la yer (dPB ) 580 thick and an overlayer (IMS blended with carbon black N660of CB ) 0.025) 1 mm t hick. The solid lines represent th e bestf i ts to the experimental data. The data sets are offset forclarity. The inset shows best-fit profiles of dP B volume fractionas a function of dista nce from t he silicon surface.



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rubber tires and tire-forming bladders where the filler(C B ) 0.10- 0.15) is added for enhanced mechanicalproperties. To compar e t he effect of car bon black w ithsilica fillers, hydrophilic silica of SF ) 0.005 wasincorpora ted into th e dPB lay er (sa mple F). The neutr onreflectivity dat a ar e shown in Figure 11 where we seethat the Kiessig osci lla t ions are a lmost completelydamped out a fter 60 min of a nnealing. Further annea l-ing for a total of 120 min ha d only a modest effect onthe inte rface dynamics . The inset shows tha t theinterfacial width reached an equilibrium value of 350, w hich is close t o tha t of the unfilled sa mple (A).

In man y applications different fil lers a re blendedtogether. An improvement in properties is found via t his

approach due to the possible interactions between thefiller t ypes. We th erefore mixed t wo of t he most commonfillers, car bon bla ck and silica of approximat ely ) 0.01each, in the BIMS-2 layer, and sandwiched this layerwi th a 600 dPB layer (sample G) . The neu t ronreflectivity data are shown in Figure 12. Despite thepresence of the carbon black, the interface quicklyreaches equilibrium, with w approximately 380 , asshown in the inset of Figure 12. Hence, the interfacialbehavior of the mixed filler la yer is char a cteristic of thesilica filler rather than the carbon black filler.

Scanning Transmission X-ray Microscopy(STXM). To examine t he effects of ca rbon black on t heequilibrium phase morphology, symmetric blends ofBIMS-1 and dPB without and with

CB ) 0.025 were

spun-cast onto a Si3N4 membra ne and an nealed for 18h at 150 C. The STXM scans of the filled and unfilledsamples a re shown in par t s a and b o f F igure 13 ,respectively. The dar k ar eas in the figure correspondto the intensity of the 285 eV *(Cd C) absorption ind P B ,17 since the dP B phase conta ins a higher concen-tration of double bonds than the BIMS phase. From thefigures we can see that dP B forms th e continuous phase,while BIMS is the mostly discontinuous phase. Carbonblack has a broad a bsorption band st ar ting at 284 eV;hence, th ese fillers ca n be imaged using a n X-ra y energybelow the onset of the dP B absorption. H owever, onlylarge a ggrega tes of carbon black could be seen since theresolution of STXM microscopy w a s compa ra ble to the

size of the average carbon clusters as determined byUSANS. Comparing the two f igures , we see that theB IMS doma ins are ta ller an d more discontinuous in thefilled blend (Figure 13a) than in the unfilled blend(Figure 13b). Figure 14 is a scanning force microscopyimage of the f i l led and unfi l led blends of the samecomposition, a nnealed a t 150 C for 18 h. ComparingFigure 14 with the STXM image (Figure 13), we cansee that the BIMS domains dewet the dP B surface inboth blends. From the cross section analysis we obtaina conta ct angle of 10 an d 6 between the B IMS-1 anddPB in the filled and unfilled blends, respectively. Fromthese values we can estimate t he equilibrium interfa cialwidth to be 80 and 240 for the f il led a nd unfil ledsystems.23 These values ar e in very good agreement w iththe interfacial width obta ined from the reflectivity da ta .Hence, the addition of small quantities of carbon blackappears to inhibit interfacial mobility. The q uant itiesof carbon black added should not alter the chemicalnature of BIMS or dPB, and the quant i t ies added aretoo small to cause a n increase in the F lory- Huggins parameter. Hence, the observed effect is probably dueto decreased dynamics wi th in the polymer mat r ixcaused by strong intera ctions between the polymer a ndthe filler. These interactions ar e w eakly present w ithsilica fillers, and hence silica fillers do not pertu rb th e

Figure 11. Neutron reflectivity data for different annealingtimes of the bilayer sample with a lower layer (dPB filled withsilica of S F ) 0.005) 600 thick a nd a n overla yer (BI MS -1) 1mm th ick . The sol id l ines represen t the bes t f it s to theexperimental data . The da ta sets a re offset for clar i ty. Theinset shows best-f i t profi les of dPB volume fract ion as afunction of distan ce from the silicon surfa ce.

Figure 12. Neutron reflectivity data for different annealingt imes of the bi layer sa mple with a lower la yer (dPB ) 600 thick and an overlayer (BIMS-2 blended with CB ) SF ) 0.01)1 mm thick. The sol id l ines represent the best f i ts to theexperimental data . The da ta sets a re offset for clar i ty. Theinset shows best-f i t profi les of dPB volume fract ion as afunction of distan ce from the silicon surface.

Figure 13. S TXM s ca n (285 eV) of (a ) 49/49/2 dP B /B IM S -1/carbon blend and (b) 50/50 dPB /BIMS -1 blend on Si3N 4membranes. Both films were annealed in a vacuum oven for18 h a t 150 C. The dark a reas correspond to the dP B phase.



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internal dynamics. Unfortunately, i t was not possibleto con t inue a nnea l ing the NR samples in order todetermine the ultimate interface since prolonged an-nealing of the bulk bilayer sa mples is not practical asdegrada tion of the polymer may result, and t he mat erialbegins to creep out of the sample holders.

Lateral Force Microscopy (LFM). A decrease inchain mobility induced by fillers should a lso reflect itselfin th e rheologica l propert ies of the filled homopolymers.Figure 15a - c shows t he SF M an d LFM ima ges (left) ofdPB f ilms, approximately 690 thick, f il led withincreasing amounts of carbon black. The topmost figurecorresponds to the unfilled dPB film. The lateral forceloop corresponding to the deflection voltage in thecantilever tra ce and r etrace signals of these images isshown on the right. From t he lat eral force loop of th eunfilled sample we can see that the PS loop is muchsmaller tha n t he dP B loop. The samples were scannedat room temperature, where the PS is glassy and highmodulus (T g ) 100 C), a nd hence th e tip slips acrossthe P S sur face, producing a sma ller frictiona l dra g. ThedPB layer, on the other hand , i s a n e las tomer andrelatively soft at room temperature (T g ) - 20 C), andhence th e viscous dra g on the tip is much larger. Themagnitude of the latera l force is directly proportionalto the deflection voltages where the proportionalityconstant is the spring constant of the cantilever. Sincethis va lue is not w ell chara cterized, we use the PS layeras a reference surface. If we assume the lateral force ofPS (denoted as V P S) to be a constant under t he sameexperimental condition, the relative normalized forcevalue (F dP B, in a rbitrar y units) of the dP B sur face equa lsthe ra tio of th e tw o potentia ls, i.e., V dP B/V P S, where V dP Ba nd V dP B a re th e deflection volta ges of the cant ilever inthe dP B loop a nd P S loop, respectively. From Figur e 15awe can see that F dP B is typically much greater than 1in the a bsence of filler. Figure 15b shows a dP B layerwith CB ) 0.005. The lateral force loop on the rightshows tha t F dP B has begun to decrease. A few largeaggr egates ha ve begun to appear on the surfa ce, thoughmost of the carbon is believed to be present a s 100 nm

particles, which a re not visible with the AFM. C loserexamination of Figure 15b shows that the aggregatesappear much broader in the LFM than in topographyimages. The aggrega tes appear h igher in the a reacovered by PS while their friction contrast is very low in the covered region. On the other hand, in the PBregion we can see that the center of each aggregate is alow friction hard core surrounded by a large coronawhere the f r ict ion i s h igher than the surroundingbackground. This a rea extends over dista nces muchlarger than the topographical disturbance, indicatingtha t the per tu rba t ion on the dynamics due to theparticles can be long-ranged. Increasing the carbonblack volume fra ction t o CB ) 0.025 (Figu re 15c) furt herdecreases t he difference in t he lat era l force loop betw eenV P S a nd V dP B until finally the two voltages a re equal atCB ) 0.15. These results a re summ ar ized in Figure 16where w e plot F dP B vs CB or SF. From the f igure wefind tha t th e lat eral force decreases with increasing CBand reaches saturat ion a t CB 0.05. In addition, thesilica fil ler reduces the lateral force, but to a lesserextent. The decrease in the lateral force indicates thatdPB is becoming harder and more glassy in its rheo-logical response to the moving tip. Clearly, carbon blackhas a more pronounced effect. These results a re con-sistent w ith the slower dyna mics observed for the sa meconcentration range in the interfacial measurements.

In Figure 15d we also show the t opographical andlatera l force loop scans of dP B filled with hydrophilicsilica part icles of SF ) 0.025. From the figure we cansee tha t the surface appears much smoother, and nolarge a ggregates ar e present. The la teral force loop isseen to change only slightly with silica filler fraction.The la tera l force vs SF results a re also plotted in Figure16. From the figure we can see that the reduction ofF dP B as a function of SF is much smaller than that ofCB. F urthermore, t he decrease of F SF w ith concentra -t ion i s much more g radua l , a nd sa tu ra t ion i s no treached within the experimental concentration exploredin this study, i .e. , SF ) 0.15. Figure 15e shows thetopogra phy and la tera l force scan s of a dP B sa mple with

Figure 14. AFM ima ge of an a nnea led B IMS -1/dP B (50/50) film of 500 (a ) with carbon bla ck filler CB ) 0.025 (4 m by 4 mimage) and (b) without ca rbon black filler (6 m by 6 m image).



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carbon black and silica particle mixtures of CB ) SF) 0 .01. From the f igure i t i s c lear that the surfacemorphology as well as friction resembles that of thesamples containing only silica even though the carbonblack content is similar to sample Figure 15b. Therelative friction of this sample is plotted as a trianglein Figure 16 where we can see tha t i t overlaps t he dat apoints on the silica fil ler curve. These results are inagreement w ith the neutron reflect ivity data whichshowed that the interfacial properties were more similarto the samples containing only the silica filler.

The effect of carbon black observed in both NR andAFM measur ements can be at tributed to the a dsorptionof the elastomer cha ins onto the filler pa rticle surfaces.These adsorbed chains a re usua lly described as boundrubber in the literature. Bound rubber was previouslyinvestigated and confirmed by extraction and atomicforce m icroscopy.24,25 These studies indicat ed tha t thedispersed filler particles act l ike a vulcanizing agentforming a cross-linked 3-dimensional elastomer net-work. In this netw ork, each filler particle is a dsorbed

by a certa in number of polymer cha ins. The number ofbound chains is a function of the filler size and hencecan vary for a given volume fraction of carbon black ifagglomeration of the particles occurs. This model as-sumes that only chains in direct contact with the fillerpar ticles a re immobilized.

The avera ge interpart icle distan ce T for a f il ler /polymer mat rix may be estimated a s follows:26

where d a nd are t he average diameter and volumefra ction of filler pa rticles and is a geometric consta ntclose to 1. The va lues of th e interpa rt ica l dista nce T a sa function of volume fraction ar e plott ed in Figure 17.Three curves for d ) 50 nm (i.e., primary par ticle sizeof carbon black characterized by the manufacturer sTEM), d ) 120 nm (i.e., USANS result for the averagerad ius of gyra t ion of the ca rbon aggrega tes in oursamples), and d ) 0.5 m (i.e. , minimum silica ag-gregate s ize) are shown in this f igure. Both NR and

Figure 15. SFM (scanning force microscopy) and LFM (lat eral force microscopy) images a nd lat eral force loops of a 690 dPBfilm (a) without filler, (b) with CB ) 0.005, (c) with CB ) 0.025, (d) wit h SF ) 0.025, and (e) with C B ) S F ) 0.01. A 230 P Slayer partially covers the dPB surface.

T ) d [ ( /6 )1/3 - 1]



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AFM indicat e tha t t he polymers behave a s if they w erecross-linked for C B > 0.025. At this volume fraction we

can extrapolat e from Figure 17 tha t t he average inter-particle dista nce is approximately 87 nm (for d ) 50nm) an d 211 nm (for d ) 120 nm). These values aresignifican tly larger t han the estimated size of the dP B

chains (R g ) 14 nm). Since we do not see both a mobilea nd bound volume fractions of cha ins, we can concludetha t the inte ract ion between the par t icles and theelastomers a re not limited to direct contact. It ha s beenestablished by several groups that an at tra ctive plana rinterface can drastically reduce the diffusion of polymerchains for dista nces on t he order of 100 nm, or 10R g.7,9,27The nature of this long-range interaction is not wellunderstood, but i t is believed to be mediated by en-tanglements within the blend.27 The planar interfacehas been approximated by a two-fluid model as il-lustra ted in Figur e 18a . One fluid is irreversible boundto the surface forming a densely cross-linked matrix(shown as green chains in Figure 18a), with a cross-linking density scaling as N 1/2 , N e, where N e i s thenumber of entanglements. Hence, chains trapped withinthis matrix (shown as blue chains in Figure 18a) arestrangulated and diffuse much slower than the freecha ins (shown as red in F igure 18a) of the bu lkliquid.28 I t i s r easonab le to assume tha t a s imi la rphenomenon also occurs in the vicinity of the at tra ctivefiller particles (Figure 18b). Hence, the filled system isthe t hree-dimensiona l an a logue of the pla na r t hin-filmsamples. Following this ana logy, the par t icles arecovered by a bound layer of polymer (green chains)which then t ra ps subsequent la yers (blue chains) andhinders th eir diffusion. Only the la yers in direct conta ctare irreversibly bound and detected by solvation meth-ods described in t he li teratur e.29 The other layers ar eentropical ly bound within the melt network but areeasily removed with solvent.

When the attractive surface is covered by organicsurfa ctan ts, a s in th e ca se of pyrogeneous silica fillers,where on ly van der Waa ls inte rac t ions wi th in thepolymer are present, it was shown that a much smallerdecrease in t he polymer dy na mics occurs.7 In a ddition,the range of the interaction is much shorter and affectsonly chains in direct contact with the surface. Even

though the bare silicon surface is known to interacts t rongly with P B,30 the surfacta nt used to disperse thecolloidal silica fillers can screen the surface interaction.Hence, only a sma ll effect on t he dyna mics is observed

Figure 16. Relative friction of 690 thick filled-dPB film vsCB a nd S F in the dPB layer. The value of the sample withmixed fillers CB ) SF ) 0.01 is plotted as the filled trian gle.

Figure 17. Interparticle distance (T ) as a function of fillervolume fraction () for fillers with particle size (d ) of 500 ,1200 , and 0.5 m.

Figure 18. S chema tic draw ings of the polymer chain structure in (a) an elastomer thin film on a flat a ttr active substrat e, (b) asection of a carbon-filled elastomer, and (c) a section of an elastomer with mixed carbon black and colloidal silica fillers. Thebound, strangulated, and free chains are shown as green, blue, and red chains. The carbon and colloidal silica aggregatesare designat ed by sma ll and large spheres, respectively. Note tha t t he size of the silica relat ive to car bon is reduced by a factorof 2 in order to show the segregation of elastomer chains at the free surface.



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even though the filler volume fraction used is similarto those of carbon black. Furthermore, a s can be seenfrom Figure 17, if the silica a gglomera tes a re in excessof 0.5 m, then the interparticle distance is too large toaffect the overall dyna mics.

I t i s in teres t ing then to specu la te as to wha t i soccurring in the samples when the two fillers are mixed.The SANS da ta on bulk sa mples where carbon a nd silicaf i l ler were mixed with BIMS show a high scat ter ingintensity which is comparable to that of the sampleswith only carbon black fillers.31 Since it is not possibleto distinguish which filler produces the scattering, wecan only stat e tha t t he number of scatterers is similarto that of the pure carbon black samples, which indi-cates that the carbon black f i l lers do not form largeaggregates with the silica such as those reported wherethe two fillers were premixed without polymer.29,32

We suspect that in the mixed filler systems polymerchains bound to carbon black par t icles are t rapped(shown as green) or have hindered mobility (shown asblue) wh ereas the cha ins in t he vicinity of the colloidals il ica f il lers behave in a manner s imilar to freepolymer (shown as red). The proposed model is shownin Figure 18c. The carbon filler acts as an effective

cross-linking agent of the polymer due to the strongintera ction w ith t he cha ins. When colloidal silica filleri s p resen t , we assume the s il ica and ca rbon b lackaggrega tes a re ra ndomly situa ted in the bulk polymermat rix. It is entirely possible that if a silica aggrega teis within a few chain dimensions, i.e., R g, then less ofthe polymer ma trix can intera ct with t he carbon blacksurface, which essentially releases these chains from theconstra ints imposed on it by the more strongly intera ct-ing surface (Figure 18c). The free chains are thenentropically excluded from the matrix and migrate tothe free surface or interfaces in analogy to the segrega-tion observed of homopolymer in a cross-linked matrix.33

ConclusionsWe successfully measur ed the int erdiffusion dy na mics

between two diss imilar e las tomers by the neutronreflectivity technique. Strong adsorption of elastomerchains to carbon black particles is indirectly observedby both neutron reflectivity and LFM techniques. Cal-culation of the critical volume fraction indicates thepolymer/filler intera ction is long ra nge. P ercolat ionwas therefore observed at CB much below the amountused in the industry. LFM mea surement on the surfacesof filled dPB films shows an increase in viscosity withas li t t le as CB ) 0.005 filler. The increase sa tur at es a ta volume fraction of CB ) 0.025. Wea ker confinem enteffects, i.e., interfa cial n a rrowing or viscosity increase,were observed w ith either NR or LF M for systems filled

with pyrogeneous silica. This was attributed to screen-ing of t he polymer/filler surface intera ctions by thesurfactant s used to sta bilize the par ticles. When bothcarbon and silica were incorporated into the dPB layer,both the surfa ce viscosity an d th e interfacial broadeningwere similar to the sa mples filled wit h only pyrogeneoussilica. This was attributed to segregation of the freepolymer an d a ssociat ed silica pa rticles to t he surfa ceand interfaces. This is analogous to the segregation offree homopolymer from a cross-linked netw ork, wh ich

in this case is formed by the physical cross-links ofpolymers adsorbed to attractive carbon black particles.

Acknowledgment. This work was supported byNSF MRSEC program. H.A. and S.G.U. are supportedby NSF Young Investigator Award DMR-9458060.

References and Notes(1) Ahmad, Z.; Ma rk, J . E . M ater. Sci . Eng. , C 1998 , 6 (2- 3),

183.(2) Koenig, J . L. Acc. Chem. Res. 1999 , 32 , 1.(3) Mark, J . E.; Erman, B .; Eirich, F. R. Science and Technol ogy

of Rubber , 2nd ed.; Acad emic Pr ess: New York, 1994; p 388.(4) Schaal , S . ; Coran, A. Y. ; Mowdood, S. K. Rubber Chem.

Technol. 2000 , 73 , 240.(5) Mori, M.; Koenig, J . L. J . Appl . Polym. Sci . 1998 , 70 , 1391.(6) Fran k, B.; G ast, A. P.; Russell, T. P.; B rown, H. R.; Ha wker,

C. Ma cromolecul es 1996 , 29 , 6531.(7) Zheng, X.; Rafa ilovich, M. H.; Sokolov, J .; Strzhemechny , Y.;

Schwarz, S . A. ; Sa uer, B. ; Rubinstein , M. Phys. Rev. Lett.1997 , 79 , 241.

(8) Lin, E. K .; Kolb, R.; Sat ija, S. K.; Wu, W. L. Ma cromolecul es 1999 , 32 , 3753.

(9) B uenviaje, C.; G e, S.; Ra failovich, M. H.; S okolov, J .; Dra ke,M.; Overney, R. Langmui r 1999 , 15 , 6446.

(10) Wang, H. C.; Powers, K. W. Elastomerics 1992 , February,22.

(11) G ursky, L. J . ; Fusco, J . V. ; Flowers , D. D. U.S. Pa tent5,532,312, 1996.

(12) Turov, V. V.; Leboda, R.; B ogillo, V. I.; S kubiszewska -Zieba,J . Langmui r 1995 , 11 , 931.

(13) P ieker, T. P .; Hinderm an n-Bischoff, M.; Ehrbu rger-Dolle, F.Langmui r 2000 , 16 , 5588.

(14) Agama lian, M.; Wigna ll, G.; Triolo, R. Neutron News 1998 ,9 , 24.

(15) Zhang, Y. et al. , data submitted to Polymer .(16) Russell, T. P. M ater. Sci. R ep. 1990 , 5 , 171; Physica B 1996 ,

221 , 267.(17) J acobsen, C.; Williams, S.; Anderson, E.; Brown, M. T.;

Bu ckley, C. J .; Kern, D .; Kirz, J .; Rivers, M.; Zhang, X. Opt .Commun . 1991 , 86 , 351.

(18) Ade, H.; Urquhart, S. G. In Chemical Applications of Syn- chrotron Radiat ion ; Sham, T. K. , Ed. ; World Scient if icPublishing, in press.

(19) Guinier, A.; Fournet, G . Smal l Angle Scat ter in g of X-rays; J ohn Wiley: New York, 1955.

(20) Porod, G. Small-Angle X-ray Scat ter ing ; Academic Press:New York, 1982.

(21) Donnet, J . B. Ru bber Chem. Technol. 1998 , 71 , 323.(22) Our experimental results indicated tha t the t hree types of

carbon black, N330, N351, and N660, have little differencein affecting the diffusion properties. Therefore, we only show the results of N351 in the following experiments.

(23) Clark, C. J .; Eisenburg, A.; LaSca la, Ra failovich, M.; Sokolov,J . ; Li, Z.; Qu, S.; Nguyen, D.; Schwarz, S.; Strzhemechny,Y.; Sauer, B. M acromolecul es 1997 , 30 , 4184.

(24) G essler, A. M.; H ess, W. M.; Meda lia, A. I. Reinforcement of elastomers wi th carbon bl ack, Plasti cs and R ubber: Pr ocess- i ng 1978 , Dec, 141.

(25) Niedermeier, W.; et al. Kaut schuk Gum mi Kun sts toffe 1995 ,48 , 611.

(26) Wu, S. J . Appl . Polym. Sci . 1988 , 35 , 549.(27) Wu, W. L.; Wallace, W. E.; van Zanten, J . H.; Bauer, B. J .;

Liu, D. W.; Wong, A. Polymer 1997 , 38 , 2583.(28) De Gennes, P. G. M acromolecul es 1986 , 19 , 1245.(29) Ha med, G. R. Ru bber Chem. Technol. 2000 , 73 , 524.(30) Zhao, W.; Ra failovich, M.; S okolov, J .; Fett ers, L.; P lano, R.;

Sanyal , M.; Sinha, S. ; Sauer, B. Phys. Rev. Lett. 1993 , 70 ,2659.

(31) Lin, M. Y. Data deferred for publication.(32) Murphy, L. J . ; Wang, M. J . ; Ma hmud, K. Rubber Chem.

Technol. 2000 , 73 , 25.(33) J inna i, H.; Hasega wa , H.; Ha shimoto, T.; Briber, R. M.; Ha n,

C. C. Ma cromolecul es 1993 , 26 , 182.

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EFFECT OF CARBON BLACK AND SILICA FILLERS IN ELASTOMER BLENDS.pdf