High Pressure Synthesis and Ordered Structure Formation of Condensation Polymers

点击翻译按钮获取中文摘要

By using a piston-cylinder type hot-pressing apparatus, we synthesized three series of aliphatic polyimides of high molecular weights by the high pressure polycondensation of the salt monomers composed of the aliphatic diamines having 6-12 methylene units and the aromatic tetracarboxylic acids such as pyromellitic acid, biphenyltetracarboxylic acid and terphenyltetracarboxylic acid at 250-320ﾟC under 220 MPa. The aliphatic polypyromellitimides and the polyimides derived from biphenyltetracarboxylic acid had high crystallinity, and their melting points exhibited an odd-even effect against the number of methylene units. The terphenyltetracarboxylic acid-based polyimides were found for the first time to have thermotropic liquid crystallinity.