纳米银对环氧树脂的增韧改性及其微波固化行为

在80℃双酚A型环氧树脂E-51中,通过还原原位构筑了超分散稳定纳米银(n-Ag);用冷冻蚀刻电镜、离心实验对其进行表征和分散稳定性评价;用间歇微波对分散系中n-Ag的微波吸收特性和环氧树脂的微波固化行为进行研究;通过拉伸试验和冲击试验考察n-Ag对环氧树脂的增韧改性行为。结果表明:银为30nm的粒状颗粒,大小均匀,有理想的分散稳定性;n-Ag对环氧树脂有显著地增韧作用,当其含量为2.0%～2.5%(质量分数)时,增韧改性效果最佳,复合材料的断裂伸长率可提高l10%～130%;原位合成n-Ag有良好的微波吸收特性,它的存在能明显减少环氧树脂的微波固化时间,当n-Ag含量超过2.5%时,微波固化时间可缩短38%;微波固化环氧树脂速度比传统加热固化速度快数倍,其抗拉伸强度和抗冲击强度也好于热固化,但拉伸断裂伸长率比热固化的小。

Role of Silver Nanoparticles in Toughening Modification of Epoxy Resin and Microwave Curing Performance

The sliver nanoparticles(n-Ag) were synthesized in-situ in bisphenol-A epoxy resin(E-51) by acetaldehyde at 80 ℃.The size,size distribution and conglomeration behavior of n-Ag were observed by freeze-etching replication transmission electron microscopy(FRTEM).The centrifuge tests were used for evaluating the dispersion and dispersion stability of n-Ag.The microwave-absorbing properties of n-Ag synthesized in-situ and the microwave curing performance of epoxy resin dispersion system containing n-Ag were studied by pulse microwave.The toughening modification effect of epoxy resin were evaluated by tensile test.The results show that n-Ag is composed of spherical particles with a homogeneity and the average size of 30 nm.The n-Ag can maintain stability,no sedimentation and no agglomeration appear in the dispersion system.n-Ag synthesized in-situ have a good microwave-absorbing property,and it can obviously decrease the microwave curing time of modified epoxy resin.The curing time of 2.5% n-Ag epoxy resin is 38% less compared to that of epoxy resin.The microwave curing rate of n-Ag epoxy resin dispersion system is several times faster than the traditional heating curing.The silver nanoparticles have a significant toughening function to epoxy resin.The toughening effect to epoxy resin is best when the mass ratio of the resin to ultra-dispersion-stability n-Ag is 2% to 2.5%.Under this situation,fracture elongation of the composite material increases by about 110%-130% compared with unmodified resin.