环氧基团修饰多壁碳纳米管及其化学交联聚氨酯复合材料的性能

碳纳米管在高分子材料中的分散性能及其二者的界面结合力决定了其复合材料的性能。用H2O2-FeSO4试剂处理多壁碳纳米管(MWCNTs)使其羟基化,再与硅烷偶联剂反应分别制备了缩水甘油醚氧丙基三甲氧基硅烷改性的MWCNTs(MWCNTs-KH560)和3-氨基丙基三乙氧基硅烷-环氧树脂改性MWCNTs(MWCNTs-E51),并和含羧基的聚氨酯(PU)混合制备了MWCNTs/PU复合材料,研究了不同链段环氧基团对复合材料性能的影响。结果表明,接枝环氧基团后,MWCNTs能明显地提高其复合材料的力学性能、热稳定性能和导电率。和MWCNTs-E51相比,MWCNTs-KH560/PU具有较高的上述性能,但断裂伸长率较低。分析认为,接枝的环氧基团可和PU链上的羧基发生开环反应而形成了化学交联结构,显著地提高了MWCNTs和PU之间的界面结合力。但MWCNTs-E51接枝的较长有机链段起增塑作用,且提高了MWCNTs之间的隧道电阻,从而降低了复合材料的力学性能和导电性能。

Properties of epoxy modified multi-walled carbon nanotubes and their chemically cross-linked polyurethane composites

The dispersibility of carbon nanotubes and their interfacial interaction in/with polymers play an important role for the performance of their composites.Multi-walled carbon nanotubes (MWCNTs) were first hydroxylated by treatment with H2O2-FeSO4 reagents,and then reacted with silane coupling agents to prepared epoxy modified MWCNTs,including γ-(2,3-epoxypropoxy)propytrimethoxysilane modified MWCNTs (MWCNTs-KH560) and 3-aminopropyltriethoxysilane-epoxy resin modified MWCNTs(MWCNTs-E51).The MWCNTs/PU composites were prepared by mixing method to investigate the effects of different epoxy chain on the performance of the composites.The results showed that the modification of MWCNTs could significantly improve mechanical property,thermal stability and electrical conductivity of the composites.MWCNTs-KH560 composite had higher above properties,but lower elongation at break compared to that of MWCNTs-E51 composite.It suggested that epoxy groups attached on the surface of MWCNTs could undergo a ring opening reaction with carboxyl group of PU macromolecules,resulting in formation of chemically bonds between them,which could greatly improve their interfacial interaction.However,MWCNTs-E51 was grafted longer organic chains,which acted as plasticizer to decrease the mechanical property of the composite.In addition,the tunnel resistance between MWCNTs was also increased,leading to a decrease in the electrical conductivity of the composites.