STUDIES ON THE STRESS RELAXATION OF POLYSTYRENES IN THE RUBBERY-FLOW REGION.
PRINCETON UNIV N J FRICK CHEMICAL LAB
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Relaxation modulus curves for monodisperse and polydisperse polystyrenes are compared and the significant effect of molecular weight distribution on these curves is shown. An empirical three-parameter equation is shown to describe well the stress relaxation behavior of monodisperse polystyrenes. New data for high molecular weight monodisperse polystyrenes are presented and used to extend the applicability of previous quantitative relations for higher molecular weights. The stress relaxation technique is shown to be sensitive to the type of plasticizer used at low concentrations. Author