Cooperative progress of crystallization and spinodal decomposition in the blends of dissimilar polycarbonates

Abstract

We investigated the structure development of the blends of bisphenol A polycarbonate (BPA-PC) and cyclohexane dimethylene polycarbonate (CHD-PC) during isothermal annealing from the miscible state. The crystallization of BPA-PC was found to be induced in the blends and small distorted crystallites developed in the interconnected structure by annealing within the immiscibility loop type phase boundary. The analysis for the time variation of the light scattering intensity revealed that 1) liquid-liquid phase separation occurred via spinodal decomposition without induction period, 2) crystallization is induced at early stage of the spinodal decomposition, 3) crystallization was largely accelerated in the blend composition in which the apparent diffusion coefficient for spinodal decomposition was larger, 4) crystallization progresses cooperatively with liquid-liquid phase separation at late stage of the spinodal decomposition. Owing to the cooperative progress, the glass transition of the blend estimated by DMA shifted to that of the neat component polymer during the crystallization.