PLA／TPU／HCNTs三元共混物的制备与性能

Preparation and Properties of Polylactide/Thermoplastic Polyurethane Elastomer/Hydroxyl Carbon Nanotubes Composite

利用熔融共混法制备了聚乳酸(PLA)/热塑性聚氨酯(TPU)/羟基化碳纳米管(HCNTs)三元共混物,对共混物熔体流变行为、结晶行为、拉伸性能和电性能进行了表征。流变测试结果表明:TPU的引入对PLA复数黏度的影响较小,而含HCNTs的三元共混物的流变逾渗阈值在1%～2%之间,含量超过2%以后,低频区复数黏度出现明显变化;DSC结果表明:TPU的引入有利于PLA结晶,而HCNTs含量的变化对PLA结晶的影响较小,HCNTs成核效应不明显;力学测试结果表明:当HCNTs含量为1%时,PLA/TPU/HCNTs三元共混物的力学性能最佳,断裂伸长率达到最大值,为96.9%,屈服强度为27.4 MPa;电性能测试表明,共混物电逾渗阈值在2%～4%之间,与纯PLA相比,共混物的电导率变化约7个数量级。

Polylactide （ PLA ）/thermoplastic polyurethane elastomer （ TPU ）/hydroxyl carbon uanotubes （ HCNTs ） blends were fabricated by melt mixing of PLA, TPU and hydroxyl carbon nanotubes. The melt rheology, crystallization, tensile properties and electrical properties of the PLA composite behaviors were investigated. Rheological measurements showed that the percolation threshold for gelation in the PLA composite with HCNTs was between 1% and 2%. The TPU had little effects on the complex viscosity of composite while PLA/TPU/HCNTs composite appeared an obvious increase of complex viscosity when HCNTs concertation was beyond 2% at low frequencies. DSC measurements suggested that both TPU and HCNTs could enhance crystallization, but nucleating effect of HCNTs was not very obvious. When the concentration of HCNTs was 1% , the comprehensive properties of the composite were optimal： elongation was 96.9% , yield strength was 27.4 MPa. Electrical percolation threshold for the conductive network was between 2% and 4%. The conductivities of the composite were far higher by about 7 orders than neat PLA, so the formation of HCNTs percolation networks could transfer electron efficiently.