纳米粒子对酯化淀粉基膜材多层次结构及热性能的影响

Characterization of Nanofiller on Multi-scale Structures and Thermal Property of Starch Ester Film

摘要:

本文以高取代度G50酯化淀粉为原料、三乙酸甘油酯为增塑剂、有机改性蒙脱土（Dellite 72T）为纳米填料，经流延法制备酯化淀粉基纳米复合膜材。借助扫描电子显微镜（SEM）、透射电子显微镜（TEM）观察膜材断面及纳米粒子的分布，利用傅里叶红外光谱仪（FTIR）、小角X-射线散射仪（SAXS）、X-射线衍射仪（XRD）分析纳米粒子对膜材的分子结构、微区结构和结晶结构的影响，并借助热失重分析仪（TG）分析纳米粒子对膜材热稳定性的影响。结果表明，纳米粒子与酯化淀粉分子相互作用弱化增塑剂塑化作用，促进淀粉分子链间聚集程度增大，形成颗粒状凸起或褶皱；加入纳米粒子后，膜材内可观察到不同厚度的层状结构（d≈ 12.57 nm、19.68 nm），而膜材的结晶结构与纳米粒子层状结构均未被破坏，此时纳米粒子与淀粉分子间的相互作用促进形成插层型结构，从而提高淀粉基膜材的热稳定性。以上结果可从结构调控角度为扩大新型淀粉基纳米复合膜材在食品包装中的应用提供理论参考。

Abstract:

The starch-based film was prepared by solvent-casting method. G50 starch ester with high degree of substitution was plasticized by triacetin and composited with organically modified montmorillonite (Dellite 72T). The features of fractured surface of the nanocomposites and the dispersion of nanofiller were analyzed by SEM and TEM. FTIR, SAXS and XRD techniques were used to characterize the molecular structures, ordered aggregation region and crystalline structures. The thermal property of starch ester film was detected by TG technology. The results indicated that some wrinkles of macromolecular aggregation were developed after the nanofiller addition, which was caused by the increasing interaction between nanofillerand G50 starch ester. The layered structures with different thickness (d≈12.57 nm, 19.68 nm) were observed in the nanocomposite，while the crystalline structures of film and the layered structures of nanofiller were scarcely changed, and simultaneously, partly intercalated structures were formed. Therefore, the thermal stability of nanocomposite was improved due to these featured aggregation structures. These findings could be helpful to the further application of starch-based materials in food packaging industry via the structural modification of starch.