高相对分子质量聚乳酸共聚物的制备及性能研究

Preparation and Properties of Relative High Molecular Weight Poly(lactic acid)-poly(ε-caprolactone)Copolymer

聚乳酸(PLA)与聚己内酯多元醇(HO—PCL—OH)的聚氯酯预聚体在双螺杆挤出机内进行熔体扩链,制备了聚乳酸共聚物,研究了熔体扩链产物的相对分子质量、形态结构、热性能和力学性能。结果表明,双螺杆反直挤出制备聚乳酸共聚物是可行的,效果比釜式反应好,熔体扩链后产物的相对分子质量随预聚体比例不同而有很大差异,当 PLA 预聚体与 PCL 预聚体的质量比为60/40时达到最大值166800,进一步增大 PCL 预聚体含量,相对分子质量下降;反应速率与反应温度有很大关系,在反应温度为160、170、180℃时,反应完成时间分别为5、4.5、3 min;共聚物呈现典型的球晶形态,表现出很好的黑十字消光现象,共聚物在120℃时所得球晶半径最大;共聚物的结晶度低于PLA 预聚体的结晶度;共聚物具有较好的力学性能,随 PCL 预聚体含量增加共聚物的韧性增加,拉伸强度与拉伸模量下降。

PLA-PCL copolymer was prepared using a twin screw extruder. The molecular weight, morphology, structure, thermal and mechanical properties were measured. It showed the chain extension of PLA was better realized by reactive extrusion than by batch-typed reactor. When the weight ratio of PLA and PCL was 60/40, high molecular weight was obtained, which decreased with further increasing content of PCL. The reaction rate was dependent on the temperature, 5, 4.5, and 3 mins were needed to complete the reaction at 160 ℃, 170 ℃, and 180 ℃, respectively. The copolymer was semi-crystalline, maltete-cross was clear recognized under polaroid microscopy. The degree of crystallinity of copolymer was lower than that of PLA prepolymer. The mechanical properties of copolymer were enhanced while increasing PCL prepolymer content, but tensile strength and modulus were decreased.