塑化淀粉分子结构变化对生物质复合材料力学性能的影响

植物纤维与淀粉结合制得用于包装领域的新型植物纤维淀粉基生物质复合材料，淀粉塑化改善了植物纤维淀粉基生物质复合材料制品性能。为揭示塑化过程促使淀粉理化性能发生变化的深层机制，对塑化后淀粉的分子结构变化展开研究。利用红外光谱分析（FT-IR）和X射线衍射分析（XRD）对热塑性淀粉内部分子之间的氢键变化和结晶度进行分析表征，以研究塑化过程中淀粉分子官能团以及结晶结构的变化，结果表明：塑化过程中淀粉结晶结构发生变化，结晶区A型结晶遭到破坏；塑化剂与淀粉分子中的羟基之间形成了新的氢键，淀粉分子羟基官能团被削弱。力学性能测试表明，塑化使淀粉分子结构发生变化后，由其制备的植物纤维淀粉基生物质复合材料的抗拉、抗压强度得到明显提升，防水性得到改善。淀粉结晶区被打破，无定形区增多，淀粉更加紧密地附着在植物纤维表面，因此复合材料的抗拉等力学性能得到了明显提升。防水性得到提高的原因在于塑化后淀粉链中亲水的羟基被削弱，淀粉的红外光谱分析中塑化淀粉的羟基伸缩振动峰减弱验证了此结论。

Influence of changes in the molecular structure of starch on the mechanical properties of biomass composites

New biomass composites that can be used in the field of packaging were prepared using starch and plant fiber.The plasticization of starch improved the mechanical properties of the starch-based biomass composites.In order to further reveal the mechanism underlying the effects,the changes in the molecular structure of starch before and after plasticization were investigated,with the aim of understanding their influence on the physicochemical properties.The changes in crystal structure were analyzed by X-ray diffraction.Changes in intermolecular hydroxyl group interactions were studied by infrared spectroscopy.It was found that the crystalline structure of starch was changed during the plasticizing process,and the type A crystalline region was destroyed.New hydrogen bonds between plasticizer and starch molecules were formed.It was shown by mechanical properties testing that the tensile strength,compressive strength and waterproofing properties of the TPS-based composites improved significantly.The starch crystallinity was reduced,the amorphous region of starch increased,it became more closely attached on the surface of the plant fiber,the adhesion strength increased,and the tensile mechanical properties improved significantly.Waterproof properties also improved due to the plasticization of starch chain as the hydrophilic hydroxyl groups become less available,and the decrease in the starch hydroxyl stretching vibration peak in the infrared spectrum of plasticized starch validates this conclusion.