环氧树脂湿热老化机理的正电子湮没实验

Moisture Absorption Mechanism of Epoxy Resin Matrices Through Positron Annihilation Technique

采用热失重(TGA)、热机械分析(DMA)、正电子湮没技术(PAL)对环氧树脂618/DDS体系湿热老化前后的性能进行测试,测试了体系湿热老化前后的吸水率和介电性能,对环氧树脂618/DDS体系的吸水机理进行了研究。结果表明,环氧树脂618/DDS体系的吸水率为3.5%,湿热老化后对体系的热失重温度没有影响,湿热老化后环氧树脂618/DDS体系损耗模量降低了250MPa,玻璃化温度降低了大约50℃,损耗峰由湿热老化前的一个峰变为两个峰。吸水后介电常数增大,介电损耗值增大。湿热老化后自由体积尺寸减小,自由体积浓度增大,体系中的水分起着增塑剂的作用,导致基体中形成更多的微裂纹。

Absorption mechanism of epoxy resin 618/4,4＇-diaminodiphenylsulfone（DDS）matrices has been studied through therrnogravimetry analysis （TGA）, dynamic mechanical analysis （DMA）, positron annihilation technique （PAL） and dielectric properties. It is found that the moisture absorption rate of epoxy resin is 3.5%. The thermal weight loss temperature doesn＇t change after absorbing water. Owing epoxy resin absorbs moisture, storage modulus decreases about 250 MPa and glass temperature decreases up to 50 ℃. And there are two peaks at loss modulus curve after epoxy resin moisture absorption. Dielectric constant and dielectric loss increase after moisture absorption. The water molecules penetrate the resin as plasticizer agent with free volume size decreasing and concentration increasing, resulting in more cracks in the epoxy resin matrix.