PLA/CNTs微发泡复合材料的制备

Preparation of Microcellular Foamed PLA/CNTs Composites

用熔融共混法制备不同含量的聚乳酸(PLA)/碳纳米管(CNTs)复合材料,以超临界二氧化碳作为物理发泡剂,通过快速卸压过程制备PLA/CNTs微发泡复合材料,并对其热性能、形貌结构和电性能进行表征和分析。热分析结果表明,在150℃时,随着发泡压力的增加,由于退火和塑化效应的共同作用,与未发泡复合材料的相比,微发泡复合材料的熔点先上升后下降。通过调控二氧化碳的压力及温度,制得具有不同微孔结构的PLA/CNTs发泡复合材料,利用扫描电子显微镜分析上述因素对微发泡复合材料泡孔结构的影响。当CNTs质量分数为3%时,PLA/CNTs复合材料在150℃,16 MPa条件下发泡制得的材料泡孔形貌较好。在150℃下,随着压力的升高,PLA/CNTs微发泡复合材料的电导率减小,在20 MPa下的电导率为3.6×10-2 S/m,与在14 MPa下的8.93 S/m相比降低约3个数量级。在16 MPa下,随着温度的升高,PLA/CNTs微发泡复合材料的电导率减小,在160℃下的电导率为2.9×10-2 S/m,与在145℃下的9.15 S/m相比降低约3个数量级。

Polylactic acid （PLA）/carbon nanotubes （CNTs） composites with different CNTs content were prepared by melt blending, and microcellular foamed PLA/CNTs composites were fabricated by a pressure-quench process using supercritical carbon dioxide as a blowing agent. The thermal property,morphology and structure,electrical property were characterized and analyzed. Thermal analysis results show that the melting point of the foamed composites increases ？rst and then decreases compared with unfoamed composites,with the increase of foaming pressure at 150℃, because of the cooperation of annealing with plasticating ef-fect. Microcellular foamed PLA/CNTs composites with different pore structure were prepared by adjusting the CO2 pressure and temperature, scanning electron microscopy （SEM） were used to discuss the effect of the above mentioned factors on the cell struc-ture of microcellular foamed PLA/CNTs composites. The cell morphology is better, when PLA/CNTs composite with 3% CNTs content is foamed at 150℃ and 16 MPa. At 150℃,with the increase of pressure,the electrical conductivity of foamed PLA/CNTs composite decreases,the electrical conductivity at 20 MPa is 3.6×10-2 S/m,which is about 3 orders of magnitude lower than that at 14 MPa, which is 8.93 S/m. At 16 MPa, with the increase of temperature, the electrical conductivity of foamed PLA/CNTs composites decreases, the electrical conductivity at 160℃ is 2.9×10-2 S/m, which is about 3 orders of magnitude lower than that at 145℃, which is 9.15 S/m.