三种添加物对聚乳酸复合膜性能影响

Effect of Three Additives on Performance of Polylactic Acid Composite Film

目的研究聚乳酸复合膜的降解性能,加快聚乳酸材料降解速率。方法选取淀粉、羧甲基纤维素钠(CMC)、聚乙二醇(PEG)等3种材料,与聚乳酸混合制备4种不同的复合膜。测定复合膜的透光率、力学性能、热性能等指标,使用红外光谱仪对复合膜的基团组成进行表征,使用磷酸盐缓冲液浸泡,测试其降解性能。结果红外光谱结果显示PLA膜与PLA复合膜的吸收峰没有明显的差别,这证明改性材料与聚乳酸没有发生化学反应。复合膜的DSC曲线显示,添加改性剂后,熔融温度变化不大,无明显影响。降解性能方面,按PLA与复合物的质量比9∶1,8∶2,7∶3,6∶4,5∶5制备多种复合膜,其中质量比9∶1,7∶3,5∶5的PLA/淀粉复合膜在第70天降解率分别为24.11%,24.8%,35.6%;PLA/CMC复合膜的3种质量比降解率为27.64%,30.37%,45.2%。按照PLA与PEG质量比为99∶1,98∶2,97∶3,96∶4,95∶5制备了PLA/PEG复合膜,其中质量比为99∶1,97∶3,95∶5的PLA/PEG复合膜在第70天的降解率分别为25.45%,38.83%,45.83%。PLA/淀粉/PEG复合膜是在PLA/淀粉复合膜的基础上添加PEG制备的,复合膜成分与PEG的质量比为99∶1,98∶2,97∶3,96∶4,95∶5,其中99∶1,97∶3,95∶5这3种复合膜的降解率为40.52%,49.54%,55.67%。各种复合膜的降解率均远优于PLA膜2.5%的降解率。结论复合材料的添加改变了聚乳酸薄膜的透光性能,增强了薄膜的拉伸强度和断裂伸长率。改性材料的添加能够在不影响聚乳酸本身结构的情况下,显著增强聚乳酸的降解率。

The work aims to study the degradation performance of polylactic acid(PLA) composite film and accelerate the degradation rate of PLA materials. Starch, sodium carboxymethyl cellulose(CMC) and polyethylene glycol(PEG) were mixed with PLA to prepare four different composite films. The light transmittance, mechanical properties and thermal properties of the films were measured. The group composition of the composite films was characterized by infrared spectrometer and the degradation performance was tested through immersion in phosphate buffer. The addition of composite materials changed the light transmittance of polylactic acid film and enhanced the tensile strength and elongation at break of the film. The IR spectra showed that there was no significant difference between the absorption peaks of PLA film and PLA composite film, which proved that the modified material had no chemical reaction with PLA. The DSC curve of the composite film showed that the temperature of Tm did not change significantly after the modifier was added. In terms of degradation performance, the degradation rates of PLA/starch composite films at the 70 th day were 24.11%, 24.8% and 35.6%, respectively, according to the mass ratio of PLA to composite materials prepared at 9∶1, 7∶3 and 5∶5. The degradation rates of PLA/CMC composite films were 27.64%, 30.37% and 45.2%. The degradation rates of PLA/PEG composite films with PEG addition of 1%, 3% and 5% were 25.45%, 38.83% and 45.83%. The degradation rates of PLA/starch/PEG composite films reached 40.52%, 49.54% and 55.67%. The degradation performance of the composite films was much better than that of PLA films, with a degradation rate of 2.5%. The addition of modified materials can significantly enhance the degradation rate of poly(lactic acid) without affecting the structure of poly(lactic acid).