Formation of Mesomorphic Phase and Crystallization in Silicone Rubber

Abstract

Silicone rubber consists of cross-linked poly(dimethyl siloxane)(PDMS). Formation of the mesomorphic phase was found in silicone rubber that is highly stretched at room temperature. The mesomorphic phase is characterized by a pair of sharp equatorial reflections in the wide-angle X-ray diffraction (WAXD) pattern. At low temperature, the stretched silicone rubber crystallizes. The WAXD patterns from the crystallized silicone rubber exhibit totally different features depending on the draw ratio. The author successfully obtained single crystals of linear PDMS. Electron diffraction patterns of the single crystals indicate that at least four different crystal forms exist. The observed WAXD patterns and their peculiar transition scheme could be explained by the combination of the crystal forms.