聚己二酸对苯二甲酸丁二酯(PBAT)共混改性聚乳酸(PLA)高性能全生物降解复合材料研究进展

High Performance and Fully Biodegradable Poly (lactic acid) (PLA) Composites Modified by Poly (Butylene Adipate-co-terephthalate) (PBAT): a Review

聚乳酸(PLA)作为一种可降解、可再生的聚合物,其优异的生物相容性和高强度、高模量的力学性能引起了许多学者的关注。聚乳酸基生物复合材料自进入人们的视野以来,由于其固有的延展性差、冲击强度低,加工过程结晶速率慢,结晶度小等缺陷,严重阻碍了其发展。关于PLA的改性研究在近十年里从未间断过,主要集中在增塑改性、增强改性、增韧改性。增塑改性是指向PLA中加入乳酸低聚物、柠檬酸酯、聚乙二醇等小分子化合物,减少PLA分子链间的相互作用,改善PLA的塑性,断裂伸长率大幅度提高,但增塑剂易渗出、迁移是如今面临的一大难题;增强改性是指向PLA加入无机填料或纳米粒子(二氧化硅(SiO 2)、二氧化钛(TiO 2)、碳酸钙(CaCO 3)、滑石粉(Talc)、蒙脱土(MMT)等)引发异相成核,改善PLA的结晶性能,但无法从根本上解决材料韧性差的缺陷;增韧改性是指加入橡胶粒子或热塑性弹性体(天然橡胶(NR)、热塑性聚氨酯(TPU)、聚碳酸酯(PC)等),虽然在一定程度上改善了PLA的韧性,但PLA的生物降解性无法保证;随着一些可降解聚酯(聚己内酯(PCL)、聚丁二酸丁二醇酯(PBS)、聚己二酸对苯二甲酸丁二酯(PBAT)等)的产生,在不改变降解性能下,对PLA进行有效的增韧改性,是聚乳酸改性研究的主要方向和研究热点。PBAT作为一种可降解聚酯聚合物,链段兼具长链脂肪烃的柔性和芳环的刚性,赋予了其优异的柔韧性,与其他聚酯材料相比,这一优势是作为增韧改性PLA的最佳选择。在早期PLA/PBAT的研究过程中就发现,由于分子链段上结构的巨大差异,PBAT与PLA的相容性差导致共混物力学性能不佳。近十年里,研究者在聚合物共混改性的基础上,选择合适的第三组分对PLA/PBAT共混体系进行改性,并取得了丰硕的成果。目前,PLA/PBAT共混体系的增韧后冲击强度由纯PLA的2.3 kJ/m 2提高至61.9 kJ/m 2。本文归纳了PBAT增韧改性PLA共混体系复合材料的研究进展,分别对物理共混(无机填料或纳米粒子和物理相容剂)、反应性共混增容剂改性PLA/PBAT体系进行了介绍,分析了PLA/PBAT共混改性体系面临的问题并展望其前景,以期为制备高性能全生物降解PLA/PBAT复合材料提供参考。

As a biodegradable and renewable material, poly(lactic acid)(PLA) has attracted numerous attention for its excellent biocompatibility and mechanical performance (high strength and high modulus). PLA matrix biocomposites have been seriously blocked by its poor ductility, low impact strength, low crystallization rate and low crystallinity since it entered people’s eye shot. Continuous efforts have been put into the modification research of PLA in the past ten years,which primarily focus on plasticizing, strengthening and toughening. Specifically speaking, plasticizing modification is adding the small molecular compound like lactic acid oligomer, citrate and polyethylene glycol into PLA, for the sake of reducing the interaction between PLA chains, improving the plasticity of PLA, and increasing the elongation at break. Yet the plasticizers are likely to exude and migrate, which is a crucial problem now. Reinforcement modification, namely heterogeneous nucleation of PLA with inorganic fillers or nanoparticles like silica (SiO2), titanium dioxide (TiO2), calcium carbonate (CaCO3), talcum powder (Talc), montmorillonite, which can improve the crystalline properties of PLA, but can not fundamentally enhance the brittleness of the material toughening modification refer to the addition of rubber particles or thermoplastic elastomer such as natural rubber (NR), thermoplastic polyurethane (TPU), polycarbonate (PC) into PLA. Although the toughness of the composite is improved to some extent, the biodegradability cannot be preserved. With the production of some degradable polyester including polycaprolactone (PCL), poly (butylene succinate)(PBS), poly (butylene adipate-co-terephthalate)(PBAT), PLA can be effectively toughened without sacrificing the degradation performance. It is the main direction and research hotspot of PLA modification. PBAT, a degradable polyester polymer, possesses the flexibility of aliphatic hydrocarbon and the rigidity of aromatic ring, which makes PBAT emerge as the best candidate for PLA toughening. In the early research of PLA/PBAT, it was found that the poor compatibility of PBAT and PLA resulted in unsatisfactory mechanical properties of the blends, which is primarily caused by the tremendous differences in the structure of molecular chain segment. In the last decade, on the basis of polymer blending modification, researchers have selected the appropriate third component to modify the PLA/PBAT blend system, and achieved fruitful results. Presently, the impact strength of the PLA/PBAT blend system after toughening has been raised from 2.3 kJ/m 2 to 61.9 kJ/m 2. This review offers a retrospection of the research efforts with respect to the progress of modification PLA/PBAT blends, and provides elaborate descriptions about physical blend (inorganic filler or nanoparticles and physical compatibility agent) and reactive blending compatibilizer modified PLA/PBAT blends. Finally, we focus on the problems faced by PLA/PBAT blending modification system, aiming at providing a reference for the preparation of high performance fully biodegradable PLA/PBAT composites.