| Abstract: | Crystallization during polymerization of p-xylylene from the gas phase has been studied between 200 and ?196°C. From room temperature to ?17°C the polymer crystal morphology changes in that the crystallinity decreases. In this range the process is thought to be of the successive polymerization and crystallization type. The morphology is in agreement with this mechanism, of the folded-chain β-polymorph type with proper epitactic orientation of the chains with respect to the support surface. At ?78°C an intermediate, poorly crystallized polymer results. At 196°C the reaction is most likely of the simultaneous polymerization and crystallization type. The morphology is, in agreement with the changed mechanism, of a metastable, irregularly folded β-polymorph type with no orientation of the chains relative to the support surface. No significant changes in molecular weight were observed in the polymers produced between 26 and ?196°C. |
