嵌段聚酯增塑剂的合成及其对PLA树脂增塑和吹膜性能的研究

Innovations in polylactic acid (PLA) production technology have reduced its production costs greatly. PLA may have applications in much broader fields, which includes plastic film products like food packages and agriculture films. However，due to its low melt strength, poor thermal stability and high brittleness, homopolymer of PLA is not suitable for blown molding, which restricts its applications. This project is planned to synthesis PBAT and PBS by polycondensation of dimethyl terephthalate, adipic acid, succinate and butanediol. Then diblock and multiblock polyesters of PBAT-b-PLA、PBS-b-PLA will be prepared by polymerization initiated by macromolecular initiators or by coupled reaction method. Using these block polyesters as plasticizers of PLA resins, the plasticizing effects of them, as well as the properties of the plasticised PLA materials, including the melt strength, mechanical strength, thermal stability, film flexibility, would be characterized. The relationship between the molecular structure of plasticizers, especially the number of units in different blocks, and the properties of the blended materials will be studied detailedly.By comparing the performance of these two kinds of blend resins,reasons cause the differences will be found out. PLA blown film resin will be designed and its blown film process will be achieved , and finally industrial applications of the R&D techniques will be realised.

聚乳酸（PLA）生产技术的革新降低了其生产成本，拓宽了其作为通用塑料的应用范围，其中包括食品包装、农用薄膜等。然而，单纯的PLA树脂熔体强度低、热稳定性差、易脆裂，很难吹塑成高品质的膜，限制了其应用范围。本项目设计以对苯二甲酸二甲酯、己二酸、丁二酸、丁二醇为原料缩聚制备PBAT和PBS，并进一步通过大分子引发聚合或者偶联反应制备PBAT-b-PLA、PBS-b-PLA的两嵌段及多嵌段聚酯。以这些嵌段聚酯作为增塑剂改性PLA树脂，表征不同分子结构的嵌段聚酯对相应共混PLA树脂的增塑效果，考察改性后材料的熔体强度、机械强度、力学性能、热稳定性和薄膜柔韧性等。深入研究嵌段聚酯增塑剂的分子结构，特别是不同结构单元的数量及增塑剂用量对材料性能的影响；对比研究PBAT/PLA、PBS/PLA两类共混树脂的性能差异，分析其成因，进而设计配方、获得PLA吹膜树脂及其吹膜工艺，实现研发技术的产业化应用。

作为一种重要的生物基可降解人工合成聚酯材料，聚乳酸（PLA）在强度、模量等性能方面与众多石油基塑料表现相当。从而使其成为替代传统非降解高分子材料的理想替代产品，在食品包装、方便餐具、无纺纤维、医疗器械、农用薄膜以及一次性耗材等方面得以应用。然而，单纯的PLA树脂熔体强度低、热稳定性差、易脆裂，很难吹塑成高品质的薄膜产品，限制了其应用范围。本项目以对苯二甲酸二甲酯、己二酸、丁二酸、丁二醇为原料，经过缩聚合成了PBAT和PBS大分子引发剂，以这些大分子引发丙交酯开环聚合，制备PBAT-b-PLA、PBS-b-PLA的嵌段聚酯材料。利用嵌段聚酯作为增塑剂改性PLA树脂，表征了不同分子结构的嵌段聚酯对相应共混PLA树脂的增塑效果，考察了改性后材料的熔体强度、机械强度、力学性能、热稳定性和薄膜柔韧性等。深入研究了嵌段聚酯增塑剂的分子结构，特别是不同结构单元的数量及增塑剂用量对共混材料性能的影响；对比研究两类共混树脂的性能，获得了PLA吹膜树脂及其吹膜工艺，并应用于可降解塑料购物袋的实际生产。在此基础上，为进一步改善PLA树脂的使用性能，我们设计合成了一系列新型PLA成核剂，研究了它们的实际使用效果；从PLA分子结构调控入手，设计合成了一系列螯合席夫碱配合物，研究了它们在催化丙交酯立体选择性聚合以及丙交酯/己内酯共聚方面的应用，合成了一系列微观结构可控的聚乳酸及其共聚物材料。