聚乳酸(PLA)是一种高模量、高强度的生物可降解热塑性聚酯。传统增塑剂通常是非生物可降解的,研究中采用低分子聚丁二酸己二醇酯(PHS)与左旋聚乳酸(PLLA)共混得到全降解体系。利用差示扫描量热仪、偏光显微镜及万能试验机对共混体系的相容性、结晶性能和力学性能进行了研究。结果表明:PLLA/PHS比值为100/0、95/5、90/10、85/15、80/20的结晶度分别为7.5%、8.7%、11.5%、14.1%、14.2%。随着PHS含量的增加,共混物的结晶度有所提高,表明PHS成功促进了PLLA结晶。此外,与纯PLLA相比,PLLA/PHS(80/20)的结晶速率增加10倍,半结晶时间缩短一半。共混体系的断裂伸长率从纯PLLA的不足10%提高至60%左右(PHS含量为20%),同时强度和模量略有降低。PHS含量增加,共混体系的弹性模量不断减小,由纯PLLA的2.25 GPa减小至PHS含量为20%时的1.86 GPa。
Polylactic acid (PLA) is a high-modulus, high-strength biodegradable thermoplastic polyester used in the packaging, textile and medical industries. Conventional plasticizers are usually non-biodegradable, the study used low molecular polyhexanediol succinate (PHS) blended with poly (L-lactic acid) (PLLA) to obtain a fully degradable system. The compatibility, crystallization and mechanical properties of the blended system were investigated by differential scanning calorimetry, polarizing microscope and universal testing machine. The results show that the crystallinity of PLLA/PHS ratios of 100/0, 95/5, 90/10, 85/15, and 80/20 were 7.5%, 8.7%, 11.5%, 14.1%, and 14.2%, respectively. The crystallinity of the blends increased with increasing PHS content, indicating that PHS successfully promoted PLLA crystallization. In addition, the crystallization rate of 80/20 was increased 10-fold and the semi-crystallization time was halved compared to pure PLLA. The elongation at break of the blends increased from less than 10% for pure PLLA to about 60% (PHS content 20%), with a slight decrease in strength and modulus. The elastic modulus of the blends decreased continuously with the increase of the PHS content, from 2.25 GPa for pure PLLA to 1.86 GPa at 20% PHS content.