淀粉/蒙脱土协同改性聚乳酸可降解复合薄膜的研究

Study on synergistic modification of polylactic acid degradable composite film with starch/montmorillonite

先采用有机季铵盐改性钠基蒙脱土(Na-MMT),使醋酸酯淀粉(SA)能够有效吸附于有机蒙脱土(OMMT)表面,再通过溶液插层技术将混合物与聚乳酸(PLA)共混改性得到可降解PLA/SA/OMMT薄膜,研究了蒙脱土的有机改性效果,并利用测试技术表征和测试了复合薄膜材料的机械性能、热稳定性、阻隔性、生物降解性和微观界面结构,研究了热降解表观活化能,探索了SA和OMMT的协同增强或增韧机理以及生物降解机制。结果表明,OMMT和SA具有协同增强与增韧PLA作用;适量OMMT在PLA/SA/OMMT可降解薄膜中分散性较好、可提高PLA/SA薄膜的阻隔性;适量OMMT的添加可加快复合膜的降解速度。

In this paper, sodium montmorillonite （Na-MMT） was modified with organic quaternary ammonium salt to obtain the organic montmorillonite（OMMT）, so that starch acetate （SA） could be effectively adsorbed. Then, based on the solution intercalation technique, the above mixture was mixed with polylactic acid （PLA） to obtain a degradable PLA/SA/OMMT film. The effect of organic modification of Na-MMT was investigated, and the mechanical properties, thermal stability, barrier properties, biodegradability and interfacial microstructure of composite films were measured by the universal material testing machine, DSC, TG and SEM. Also, the apparent activation energy of thermal degradation of composite films was studied. Furthermore, the synergistic strengthening or toughening effect of SA and OMMT and the biodegradation mechanisms of composite films were explored. The results showed that OMMT and SA had synergistic enhancement and toughening for PLA. The amount of OMMT in PLA/SA/OMMT degradable film had good dispersibility and could improve the barrier properties of PLA/SA film. The addition of OMMT could accelerate the degradation rate of composite films.