Abstract
The specific heat capacities Cp of blends consisting of cis-polyisoprene (PI) and poly(vinylethylene) (PVE) were measured in the temperature range from 80 to 320 K by using an adiabatic calorimeter. The configurational heat capacities Cconf of blends around the glass transition temperature Tg have been determined by subtracting the vibrational heat capacities estimated with the Einstein and Debye theories. The Cconf vs temperature T curves of the blends exhibit double sigmoidal increase at two glass transition temperatures Tg1 and Tg2 and can be resolved into two empirical sigmoidal curves. For each sigmoidal curve with the index j = 1 or 2, we have also determined the magnitude of the jump ΔCj and the broadness parameter Bj of the sigmoidal curves. The dielectric relaxation spectrum for the primary process of PI/PVE blends is known to be bimodal due to dynamical heterogeneity. The relationship between the bimodal dielectric segmental relaxation and the double glass transition processes has been analyzed.
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