表面酯化修饰纳米纤维素在聚乳酸复合膜中的应用

本文分别以纳米纤维素和酶促酯化改性后的纳米纤维素为增强材料,以聚乳酸为基质制备了聚乳酸-酯化纳米纤维素复合膜材料。通过对不同种类复合膜材料的透光性、拉伸性能、透湿率等各项性能指标的测定,对比研究了酯化改性前后纳米纤维素对聚乳酸膜、聚乳酸复合膜性能的影响;并探讨了脂肪酸链长对聚乳酸复合膜性能的影响。研究发现,纳米纤维素对聚乳酸的阻隔性能有一定的增强效果,但其不易分散于聚乳酸中,导致所制备的复合膜机械性能降低,膜表面出现明显的纳米纤维素聚团。经酯化疏水改性后所得到的纳米纤维素能分散良好于有机溶剂中,因而酯化改性对聚乳酸-酯化纳米纤维素复合膜的透明度影响甚小;同时,由于酯化纳米纤维素分散性良好,与聚乳酸具有更强的界面结合力,因此以酯化改性对酯化纳米纤维素-聚乳酸所制备的复合膜材料的机械性能、阻隔性能等较之未改性纳米纤维素-聚乳酸复合膜有了显著提高。这种新型复合膜可作为可降解性食品包装材料,在食品化工等领域有着良好的应用前景。

Application of Surface AcylatedNanocrystalline Cellulose in Polylactic Acid Based Composite Membranes

Using nanocrystalline cellulose (NCC) and surface acylated NCC were used as strengthening agents, a newpolylactic acid (PLA) based composite membranes were prepared which can be used as biodegradable food packaging materials. The performance of the composite membranes were tested to investigate the effects of acylation modification on the composite membranes.NCC do have reinforce barrier properties on PLA, but not so obviously because of its bad dispensionin PLA, the reunion of NCC also resulting in the reduction of mechanical properties of composite membrane. After hydrophobically modified, NCC ester can be dispersed well in organic solvent, thus has little effect on the transparency of composite films, due to the stronger interfacial bonding force between polylactic acid and NCC ester, the mechanical and barrier properties of the composite films were promoted. As a new kind of degradable food packaging materials, the composite membranes showed great application potential in food realted industries.