碳纳米管的表面改性对环氧树脂低温(77K)冲击性能及热膨胀系数的影响

Effects of functionalized MWCNTs on the impact strength at cryogenic temperature(77 K) and coefficient of thermal expansion of MWCNTs/epoxy resin

采用混酸氧化及表面接枝改性的方法制备了表面含不同官能团的多壁碳纳米管(MWCNTs),并研究了不同MWCNTs对环氧树脂的低温(77K)抗冲击性能及热膨胀系数(CTE)的影响。结果表明:通过接枝反应将—NCO基团封端的PEO齐聚物引入MWCNTs表面,可提高MWCNTs在环氧树脂基体中的分散性,加强MWCNTs与环氧树脂的界面作用;相对于纯环氧树脂,添加质量分数为0.5%的纯MWCNTs、氧化MWCNTs和表面接枝MWCNTs改性后的环氧树脂的低温冲击强度分别升高了10.27%、26.13%和32.95%,而CTE则分别降低了14.79%、29.59%和40.29%。这表明表面接枝改性MWCNTs可明显提高环氧树脂基体的低温抗冲击性能并降低环氧树脂在玻璃化转变温度下的CTE。

The modified multi-walled carbon nanotubes（MWCNTs） with different functional groups on the surface were prepared by the methods of mixed acid oxidation and surface graft reaction.The impact strength at cryogenic temperature and the coefficient of thermal expansion（CTE） values for the pure epoxy and different MWCNTs modified epoxy were studied.The results show that —NCO group terminated PEO oligomer can be introduced to the surface of MWCNTs through surface grafting reaction,which can improve the dispersion state of nanotubes and strengthen the interfacial bonding between nanotubes and epoxy matrix.In comparison to pure epoxy,impact strength at cryogenic temperature of MWCNTs,O-MWCNTs and S-MWCNTs modified epoxy composites with 0.5% mass fraction are increased 10.27%,26.13% and 32.95%,respectively,and CTE values under Tg range are decreased 14.79%,29.59% and 40.29%,respectively.It indicates that S-MWCNTs can improve the impact strength at cryogenic temperature and decrease the CTE values under Tg range of epoxy resins.