耐高温高韧性聚酰亚胺树脂分子量与性能关系

首先，采用具有非对称结构的2，3，3'，4'-联苯四甲酸二酐（α-BPDA）、二胺以及反应性封端剂4-苯乙炔苯酐（4-PEPA）合成了分子量分别为1 500、2 500、3 500、5 000 g/mol的热固性聚酰亚胺树脂；然后，采用FTIR、XRD、DSC、DMA、TGA和流变等表征分析方法，研究了分子量与固化反应过程、聚集态结构、耐热性能、流变性能、韧性性能的关系及其影响机制。结果表明:随着分子量增加，热固性聚酰亚胺树脂的玻璃化转变温度由369 ℃下降至344 ℃；熔体最低黏度由15.5 Pa·s增加至37 090.0 Pa·s；冲击强度由25.93 kJ/m2提高到45.04 kJ/m2。增大分子量导致热固性聚酰亚胺树脂的玻璃化转变温度和工艺性能下降，但韧性提高。 

Relation between molecular weight and properties of high temperature and high toughness polyimide resin

Thermoset polyimide resins with molecular weight of 1 500, 2 500, 3 500, 5 000 g/mol were synthesized firstly by asymmetric dianhydride 2,3,3',4'-biphenyltetracarboxylic dianhydride (α-BPDA), diamines and 4-phenylacetylene anhydride (4-PEPA) as the endcapping agent. Then, the relation between molecular weight and curing reaction process, aggregation structure, heat resistance, rheology property and toughness property, and its mechanism were investigated by characterisation and analyses methods such as FTIR, XRD, DSC, DMA, TGA, rheometer and so on. The results indicate that with the increase of molecular weight, glass transition temperature of resin decreases from 370 ℃ to 344 ℃, the lowest melt viscosity increases from 15.5 Pa·s to 37 090.0 Pa·s and impact strength also increases from 25.93 kJ/m² to 45.04 kJ/m².The glass transition temperature and processability of the thermoset polyimides will reduce by increasing its molecular weight, but toughness will increase.