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发表时间：2022-10-09
发表刊物：高分子学报
所属单位：化工学院
期号：3
页面范围：399-410
ISSN号：1000-3304
摘要：Three types of chain-extended bismaleimides with aromatic hetero-cycle structure (PBMI,FBMI,ZBMI) were synthesized,and their chemical structure and thermal properties were characterized by nuclear magnetic resonance (NMR) spectroscopy,infrared (IR) spectroscopy,differential scanning calorimeter (DSC),thermo-gravimetric analyzer (TGA) and dynamic mechanical analyzer (DMA),respectively.PBMI,a phthalide-containing bismaleimide,was prepared with phenolphthalein,o-cresolphthaleine and thymolphthalein as initial raw materials.With increasing number and volume of substituent groups,the solubility of PBMIs in common organic solvents was enhanced while their reactivity reduced.Three cured PBMI resins showed excellent thermal stability and heat resistance.Their glass transition temperatures (Tg) and the temperatures of 10％ weight loss,both decreased with the number of alkyl chain substituents to aromatic rings,were in the range of 324-364 ℃ and 454-495 ℃,respectively.The cured PBMI with only methyl groups demonstrated an optimal moisture resistance.FBMI,a fluorene-containing bismaleimide,was subdivided into ether-type FBMI and ester-type FBMI.The melting point of the ether-type FBMI was lower than that of the ester-type FBMI,and the reactivity of the two resins were comparable with each other.The heat resistance and moisture resistance of the cured products of the former were superior to those of the latter.In addition,the incorporation of methyl groups into the molecular skeleton of the two types of FBMI resulted in a decrease of above-mentioned properties.The Tg values of the four FBMI cured products were all above 350 ℃ and the maximal Tg value reached above 400 ℃.ZBMI,a 1,3,4-oxadiazole-containing bismaleimide with asymmetric molecular structure,was designed and synthesized based on the characteristics of synthetic process of 1,3,4-oxadiazole moiety.Three ZBMI monomers exhibited good solubility and different reactivity of two end-capped unsaturated double bonds.Their cured products with fully aromatic heterocyclic structure were characterized by higher thermal stability and the initial decomposition temperature of 500 ℃.
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