环氧树脂/苯并噁嗪共聚物的固化行为及其耐热性

Curing Behaviors and Heat Resistance of Epoxy/Benzoxazine Copolymers

为了探索环氧树脂/苯并噁嗪的固化行为及其共聚物的性能,本文以双酚A型环氧树脂(E51)为基体,双酚A型苯并噁嗪(BA-mt)为改性剂,以4,4-二氨基二苯砜(DDS)为固化剂,制备了苯并噁嗪/环氧树脂共聚物(EDBx,x代表苯并噁嗪的质量分数)。本文研究了环氧/苯并噁嗪体系的流变特性、固化行为、固化物的断面形貌以及其碳纤维复合材料在高温下的力学性能。结果表明,BA-mt能够促进共混树脂体系的固化,从而缩短凝胶时间;当BA-mt质量分数为20%时,EDB20固化后在N_(2)氛围下800℃的残炭率可达24.6%。此外,EDB20固化物的T_(g)值由纯E51/DDS的180℃提高至190℃。当BA-mt质量分数为40%时,EDB40拉伸强度为74.4 MPa,与E51/DDS相近。另外,EDB20在180℃下的弯曲强度和弯曲模量分别比E51/DDS高出50%和97.8%,这表明经BA-mt改性后的树脂基复合材料具有良好的高温力学性能。

The curing behaviors of epoxy/benzoxazine blends and the properties of their copolymers were investigated in this work.The benzoxazine/epoxy resin copolymers(EDBx,x represents the mass fraction of benzoxazine)were prepared by using bisphenol A-epoxy resin(E51)as the matrix,bisphenol A benzoxazine(BA-mt)as the modifier,and 4,4′-diaminodiphenyl sulfone(DDS)as the curing agent.For the epoxy/benzoxazine systems,their rheological properties,curing behaviors,cross-sectional morphologies of the fracture surfaces,and mechanical properties of the carbon fiber composites at high temperature were examined.The results indicate that BA-mt could accelerate the curing of the blended systems,reducing the gel time.When the BA-mt mass fraction is 20%,the char yield of the resin system at 800°C under N 2 atmosphere reaches 24.6%.Additionally,the T_(g)of the resin system increases from 180°C to 190°C.The tensile strength of EDB40 is 74.4 MPa,which is very close to E51/DDS.Furthermore,EDB20 exhibits higher bending strength and bending modulus at 180°C,which are respectively increased by 50%and 97.8%compared to E51/DDS.This indicates that the BA-mt modified resin composites have good high-temperature mechanical properties.