Rheological Implications of the Reduction in Viscosity of SBR Copolymers During Mixing

摘要

Compound properties have not generally been quantitatively associated with a specific change in the elastomer rheology during mixing. In the present work different macromolecular patterns are related to the reduction in viscosity of the elastomer as a function of strain. Deformation history is investigated in terms of transient shear flow and the nonlinear response of a highly branched SBR gum elastomer from emulsion polymerization is compared with those obtained using styrene-butadiene random copolymers with controlled architecture and comparable Mooney Torque (linear, star branched, randomly branched). The occurrence of multiple overshoots during start-up of steady shear, to be associated with chain stretch and hierarchical relaxations, is discussed in terms of nonlinear rheology.