聚羟基脂肪酸酯(PHAs)的结晶行为与力学性能调控

Crystallization Behavior and Mechanical Properties of Bio-Based Polyhydroxyalkanoates

聚羟基脂肪酸酯(PHAs)是目前唯一一种由微生物直接合成的生物基聚酯,能够实现材料合成、制品加工和回收降解的全周期绿色生态循环,因而在纺织纤维、包装材料、生物医用材料等领域有着潜在的应用市场。然而,PHAs自身也存在着结晶速率慢、球晶尺寸大和二次结晶等不利结构因素,限制了产品的应用性能。因此,重点从物理异相成核诱导、化学长链支化结构设计和外场多级牵伸诱导3个方面阐述PHAs结晶结构和力学性能的改性研究进展。首先,具有高耐热的无机纳米材料(如硫化钨)可显著提高PHAs异相成核能力;其次,长链支化结构可以提高PHAs熔体强度;再次,在多级牵伸诱导作用下,可协同诱导PHAs聚集态的晶型结构演变,从而获得强度高、韧性好的PHAs纤维。最后,对PHAs的研究和应用做出了进一步的展望。

Polyhydroxyalkanoates(PHAs)is the only bio-based polyester directly synthesized by microorganisms,which can achieve a full green ecological cycle from raw material preparation,product processing to material degradation.With the advantages of being green and environment-friendly,PHAs have potential applications in textile fibers,packaging materials,and biomedical materials.However,PHAs also have unfavorable structural factors such as slow crystallization rate,large spherulite size and secondary crystallization,which limit their application.Therefore,this paper mainly focuses on the research progress of modification of the crystal structure and mechanical properties of PHAs from three aspects:the heterogeneous nucleation effect,the long-chain branching structure design and the external field induction.First,inorganic nanomaterials with high heat resistance(tungsten sulfide)can be used to significantly improve the heterogeneous nucleation ability of PHAs.Secondly,the long-chain branched structure can be used to compensate for the lack of PHA melt strength.Furthermore,the crystal form of PHAs can be changed by the synergistic effect between heterogeneous nucleation,long-chain branching and drawing process.Finally,further research directions and applications of PHAs have also been presented.