一种半晶性联苯酯侧基聚酰亚胺

聚酰亚胺作为一种高强度、高模量、耐热性材料正越来越广泛地得到应用．但是，因其刚性或半刚性的分子链，以及分子之间强烈的相互作用，使其熔融温度很高(很多高于其分解温度)，并且不溶解于大多数有机溶剂，这为成型加工带来困难．在聚酰亚胺大分子主链上引入侧链或侧基，

A SEMICRYSTALLINE POLYIMIDE WITH BIPHENYL ESTER PENDENT GROUPS

A novel polyimide(PI) containing pendent biphenyl ester groups was synthesized from 3,5-diaminobenzoic-4′-biphenyl ester (DABBE)and 3,3′,4,4′-oxydiphthalic dianhydride(ODPA) by a one-step high-temperature polycondensation in m-cresol.This PI is a semicrystalline polymer.Lots of short fine fibric crystals with length and diameter about 20、μm and 1、μm respectively disperse randomly in the PI film. The optical textures and the X-ray diffraction patterns of the PI solution and film show that the PI main chains are in the extended conformation and pack parallel to each other, and the pendent biphenyl ester groups occupy the space between the main chain layers,more or less perpendicular to the main chains.At the same time, mechanical and thermally stable properties of the PI film were investigated. The excellent mechanical properties of general polyimide films are reasonably maintained, the polyimide film with pendent groups showes higher tensile strength and modulus and lower T g. TGA study showes a typical two-step weight loss behavior corresponding to the pyrolysis of pendent groups and main chains of the PI,respectively.