Deformation and annealing behavior. III. thin films of polycarbonate,isotactic polymethyl methacrylate,and isotactic polystyrene

The morphology of thin films of polycarbonate (PC), isotactic polymethyl methacrylate (i-PMMA), and isotactic polystyrene (i-PS) were studied by bright field, diffraction, and dark field transmission, electron microscopy. The films were thermally annealed both before and after uniaxial deformation. The undrawn i-PMMA did not develop a crystalline texture upon annealing whereas the undrawn i-PS developed a random arrangement of lamellae. Thermal crystallization of undrawn PC has been shown to occur through the growth and merging of a nodular structure into fibrillar spherulites. Deformation of gold-decorated samples indicated a nonhomogeneous structure in the amorphous polymer on the 200-500 A scale. Thermal annealing of drawn samples resulted in fibrillar lamellae arranged perpendicular to the draw direction for all three polymers, indicating the straining has a marked influence on the crystalline morphology. This morphology is compared to similar morphologies reported in the literature for crystallization from stressed melts. High-resolution dark field micrographs confirm this morphology and indicate variations in crystallite size, depending upon the polymer and deformation conditions.