EFFECT OF CRYSTALLINE PARAMETERS ON THERMAL TRANSITIONS AND MECHANICAL RELAXATIONS - STUDIES ON MISCIBLE BLENDS OF ETHYLENEVINYL ACETATE COPOLYMERS WITH POLYCHLOROPRENE

The crystalline parameters obtained from wide angle X-ray scattering ( WAXS) indicate generation of a new amorphous phase on blending poly(et hylene-vinyl acetate) (EVA, vinyl acetate content 45%) with polychloro prene (CR). The broad and sharp thermal transitions and mechanical rel axations obtained from Differential Scanning Calorimetry (DSC) and Dyn amic Mechanical Analysis (DMA) are caused by a large number of small c rystallites and a small quantity of large crystallites present in EVA and CR respectively. The blends are compatible in all compositions. Th e new composite model proposed for isotropic miscible blends in line w ith the model for crystal-amorphous composite system shows that beta-r elaxations reside solely in the amorphous part whereas gamma-relaxatio ns are partly of amorphous origin.