| Abstract: | The morphology of polyethylenes formed upon polymerization by γ-radiation below the melting point in various reaction media was investigated by using electron microscopy and scanning electron microscopy. When the polymerization was carried out in bulk at 30°C and in methanol, the polymer was fibrillar, and a small-angle x-ray scattering curve of the polymer did not indicate the existence of a long period. This suggests that the chains in the crystals have an extended conformation. When the polymerization was carried out in the presence of xylene at 30°C, platelet crystals having a folded structure were obtained. It was thus shown that the morphology of the growing polymer crystals is very much affected by the solubility of the polymer in the reaction medium. The effect of stirring during polymerization on the crystalline morphology was also studied. |
