Analysis of Water Barrier, Mechanical and Thermal Properties of Nanocoposites Based on Cassava Starch and Natural Clay or Modified by Anionic Exchange

Biopolymer films have several industrial applications because they are environmentally sustainable. Cassava starch is a biopolymer that is easily available, but has limitations: it is hydrophilic, poorly resistant and degradable. The improvement of these properties was proposed in this research from the use of bentonite clay (BT) as a filling material. The compatibilization of this in the polymer matrix was obtained by ion exchange with an organic anionic surfactant. The formation of intercalated or exfoliated starch nanocomposites in the presence of natural or modified clay was characterized by XRD, FTIR, AFM and SEM. The improvement of water vapor, thermal and mechanical properties was investigated by WVP, solubility, TGA and tensile test. The starch nanocomposites in the presence of modified clay showed a better result than those of natural clay. There was no significant difference in the color of the starch film in the presence of the natural or modified clay.

生物聚合物薄膜因具备环境可持续性，拥有诸多工业应用场景。木薯淀粉是一种易得的生物聚合物，但存在诸多局限：其亲水性强、耐性能欠佳，且可生物降解。本研究采用膨润土（Bentonite Clay，BT）作为填充材料，对上述性能缺陷进行改进；通过与有机阴离子表面活性剂进行离子交换，实现膨润土在聚合物基体中的相容化改性。借助X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、原子力显微镜（AFM）及扫描电子显微镜（SEM），对天然或改性膨润土存在下插层型或剥离型淀粉基纳米复合材料的形成过程进行了表征。通过水蒸气透过率（Water Vapor Permeability，WVP）测试、溶解度测试、热重分析（TGA）及拉伸试验，对改性后薄膜的水蒸气阻隔性、热性能与力学性能的提升效果开展了研究。结果显示，添加改性膨润土的淀粉基纳米复合材料，其综合性能优于添加天然膨润土的样品。无论添加天然膨润土还是改性膨润土，淀粉薄膜的色泽均无显著差异。