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Some considerations concerning the dynamicmechanical properties of cured styrene–butadiene rubber/polybutadiene blendsAJ Marzocca, S Cerveny and JM Me ´ndezUniversidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departmento Fı ´ sica, Cuidad Universitaria, LPMPyMC, Pabello ´ n 1, Buenos Aires (1428), Argentina

INTRODUCTION

(Received 14 April 1999; revised version received 28 July 1999; accepted 27 October 1999

Correspondence to: AJ Marzocca, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departmento Fı ´sica, CuidadUniversitaria, LPMPyMc, Pabello ´n 1, Buenos Aires (1428), ArgentinaContract/grant sponsor: University of Buenos Aires; contract/grant number: 01/TY05

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EXPERIMENTAL TECHNIQUES

RESULTS AND DISCUSSION

Table 1. Compound formulations (in phr), density and t 100% (MDR2000, 433K)

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Figure 1. (a) Loss tangent (tan ) as a function of the temperature of SBR/ BR blends. The dashed lines in samples A and B correspond to the ttinggaussians. (b) Storagemodulus G as a function of thetemperature of SBR/ BR blends.

Table 2. Glass transitiontemperature ( T g) and areabelow the peak ( ) of tancurves of gure1.a

Figure 2. Glass transition temperature T g of SBR/BR blends as a functionof weight percentage of BR ( BR) —, Fox equation.

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Figure 3. Storage modulus G as a function of the temperature BRcompound and BR gum. For details see text. Figure 4. Normalized loss tangent (tan n) of SBR/BR blends.

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ε

Figure 5. Normalized loss tangent of BR compound (sample F) withcrystallization. Two gaussian curves are shown using dotted lines.

Figure 6. Loss of crystallinity ( ) as a function of weightpercentage of BR.

Figure 7. Mooney stress M (eqn (10)) vs deformation function f ( ) forSBR, BR and 50SBR/50BR.

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Table 3. Crosslink densities (2 M c) 1 , crosslink modulus ( G cr) and kinetic parameters of SBR/BR blend at 423K

Figure 8. Normalized rheometer curves tted to eqn (18) for SBR/BRblends at 423K: experimental data; —, eqn (18).

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CONCLUSIONS

ACKNOWLEDGEMENTS

REFERENCES