多壁碳纳米管对聚甲醛性能的影响

将多壁碳纳米管(MWCNTs)和聚甲醛(POM)在转矩流变仪中熔融混合得到POM/MWCNT复合材料.研究了复合材料的形态,导热性能,导电性能,流变性能和结晶性能.结果表明,MWCNTs在没有经过处理的情况下能够均匀地分散在POM基体中;当向POM中添加1.0 wt%含量MWCNTs时,复合材料的导热系数上升到0.5289 W/(K m),比纯POM的导热系数0.198 W/(K m)提高1.5倍,通过有效介质方法(EMA)验证了体系导热系数提高幅度不大的原因是MWCNTs与POM之间形成了很高的界面热阻;当MWCNTs的含量为1.0 wt%时,体系产生了导电逾渗效应,逾渗值在0.5 wt%~1.0 wt%之间;MWCNTs对POM有显著的成核作用,当向POM中添加0.5 wt%含量的MWCNTs时,POM的结晶温度提高6℃左右,但当MWCNTs的添加量进一步增加时,结晶温度几乎不再变化,成核效果呈现"饱和"状态.另外,材料的复数黏度,储能模量和损耗模量随MWCNTs含量的增加而增加.

EFFECT OF MULTI-WALLED CARBON NANOTUBES ON THE PROPERTIES OF POLYOXYMETHYLENE

Polyoxymethylene(POM)/multi-walled carbon nanotubes(MWCNT) composites were prepared by melt mixing MWCNTs and POM in a rotational rheometer.The morphology,conductive property,dynamic rheological property,thermal property and crystallization behavior of the composites were investigated.It was found that MWCNTs,without any modification,dispersed homogeneously in the POM matrix.The conductive percolation effect was observed when the MWCNTs content was 1 wt%,with the percolation threshold between 0.5 wt%～1.0 wt%.The thermal conductivity of POM/MWCNT composites increased to 0.5289 W/(K m) with the addition of 1.0 wt% MWCNTs,1.5 times higher than that of pure POM [0.198 W/(K m)].When the content of MWCNTs is further increased,the thermal conductivity of the composites hardly changed.The effective media approach(EMA) was used to confirm that the moderate increase of thermal conductivity was contributed to the interfacial resistance between MWCNTs and POM.MWCNTs have significant nucleating effect on POM,and 0.5 wt% MWCNTs could enhance the crystallization temperature of POM by about 6℃,but did not improve further with additional addition of MWCNTs.The complex viscosity,storage modulus and loss modulus of the composites increase with the content of MWCNTs.