超分散稳定纳米Ag在环氧树脂中的原位构筑及其增韧改性作用

In-situ synthesis of ultra-dispersion-stability nano-Ag in epoxy resin and toughening modification to resin

微波辅助合成了具有超分散稳定作用,且可作为纳米银前驱体的油溶性羧酸银;在80℃下,在环氧树脂介质中,以乙醛为还原剂原位构筑了纳米银(n-Ag),进而制备了纳米银环氧树脂复合材料;用冷冻蚀刻电镜、离心实验对分散系进行了表征和评价;测试了原位构筑n-Ag和添加分散n-Ag对环氧树脂复合材料的力学性能。结果表明:原位构筑的银为30nm的粒状颗粒,大小均匀,在介质中无团聚行为;n-Ag分散系经72h普通离心和56h非连续超离心均未发生沉降,表现出理想的分散稳定性,n-Ag对环氧树脂有显著地增韧改性作用,但原位构筑的n-Ag其增韧改性效果明显好于添加的n-Ag。当原位构筑的n-Ag含量为2.0%～2.5%时,增韧改性效果最佳,此时,复合材料的拉伸强度、抗冲击强度、断裂伸长率可分别提高80%～90%、100%和110%～130%。

The oil-soluble sliver salt which could been used as hyper-disperston stabilizer ann precursor synthesiing nano-Ag was synthesized by microwave irradiation. The sliver nanoparticles （n-Ag） were synthesized in-situ in epoxy resin by liquid reduction with acetaldehyde at 80℃. The diameter, diameter distribution and con- glomeration behavior of n-Ag in dispersion were observed by freeze-etching replication transmission electron microscopy（FRTEM）. Formation and dispersion stability mechanism of n-Ag were explained. The tests of normal centrifuge and high speed centrifuge were used for evaluating the dispersion and dispersion stability of n-Ag. Influences of n-Ag modifier of different acquisition methods（through in-situ synthesizing method or adding meth- od） on mechanical properties of epoxy resins composites were measured by mechanical test. The results show that n-Ag is composed of spherical particles with an uniform and average size of 30nm. n-Ag dispersion can maintain stability, no sedimentation and no agglomeration in epoxy resin medium,and didn＇t come into being sedimentation through 72h centrifuge tests and 56 h intermittent high speed centrifuge tests, n-Ag has toughening function to epoxy resin, but toughening effect of ultradispersion-stability n-Ag synthesized in-stiu in epoxy resin is better the one of adding n-Ag. The toughening effect to epoxy resin is best when the mass ratio of ultradispersion-stability n-Ag of resin is 2% to 2. 5%. Under this situation, the tensile strength, compression strength and breaking elongation of composite material increased respectively by about 80%-90%, 100%, 110%-130% compared with unmodified resin.