Morphological Structure And Properties Of Crystalline Syndiotactic 1, 2-Polybutadiene

The crystalline syndiotactic 1,2-polybutadiene is a kind of semicrystalline polymer ,at different polymerization conditions, 1,2 unit content and sydiotacticity will be diffent,which will lead to diffent structure and properties. Generally speaking , the polymer with higher crystalline degree has plastic properties ,while the one with lower crystallinity exhibits rubber properties. So, there is theory and application interest in studying its struture and properties. In past few decades, however, most of research work were focused on the preparation, physical properties and application of the polymer, while almost no investigation on its crystallization and morphology has been reported. The main reason is due to the large mount of double bonds contained in the side chains of the polymeric molecules, which will cross-link at higher temperatures (>150℃). Especially for the polymers with high syndiotacticity, the thermal cross-linking reaction will take place very easy during the melt crystallization process because of their high melting temperature (>200℃). This makes the morphologic study of the polymer very difficult. This thesis has studied systemically morphological structure and properties of crystalline syndiotactic 1,2-polybutadiene using DSC and PLM techniques, and obtained the following results: The self- seeding nucleation results in obvious increase of the crystallization temperature of the syndiotactic 1,2-polybutadiene ;the necleus density increases about two orders; and the spherulite size decreases markedly after the self-seeding nucleation treatment.