零维BEN粒子/二维GO片层纳米复合粉末体系制备高性能PLA三元纳米复合材料的研究

How to prepare the advanced polylactic acid (PLA) composites which not only have high toughness but also have the full biodegradability is an important project in polymer research. . Recently, we have invented a novle biodegrable elastomer nanoparticles (BEN) which was made of aliphatic polyester and has good compatibility with the PLA. Interestingly, the BEN has high crosslinking density on the surface due to the irradiation vulcanization in polyester emulsion, which makes it possible that the BENs can be dispersed well in PLA matrix when they are mixed with PLA. . This proposal introduces a new method to prepare the advanced PLA/BEN/graphene oxide (GO) ternary nanocomposites. Firstly, the BEN/GO nanocompound powder in which the nanoscale BEN and GO lamella are adhered each other with physical adsorption is fabricated by spray drying the mixture of irradiation vulcanized polyester emulsion and GO slurry. Then the BEN/GO nanocompound powder is mixed with melt PLA in an internal mixer. Because the BEN is easily dispersed well in PLA, the GO lamella adhered with the surface of BEN is also easily dispersed well in PLA matrix with the help of carrier of BEN during the mixing. Therefore, the PLA/BEN/GO ternary nanocomposites with controlled micromorphology is prepared.. On the one hand, this proposal aims to study the dispersion mechanism of BEN and GO lamella in PLA matrix in order to control the micromophology of the PLA/BEN/GO ternary nanocomposites. On the other hand, this proposal investigates some advanced properties of the PLA/BEN/GO ternary nanocomposites. The synergistic effect of good dispersion of BEN and GO lamella on toughening the PLA is studied by using both the traditional elastomer toughening mechanism and modification of PLA crystallization induced by the good dispersion of BEN and GO on toughening PLA. The accelerated biodegradability of PLA/BEN/GO ternary nanocomposites induced by good dispersion of BEN in PLA matrix is also studied. Meanwhile, this proposal investigates the effect of GO lamella on improving the strength and heat resistance of the PLA composites. Above studies are very important to prepare the advanced PLA composites with high toughness, full biodegradability and high heat resistance, which will be benefit for further polymer research and polymer industry.

提高聚乳酸（PLA）的韧性、结晶速率和耐热性而不牺牲其宝贵的生物降解性，具有重要的应用和研究价值。在前期制备生物降解聚酯弹性体纳米粒子（BEN）的基础上，本课题先制备BEN粒子和氧化石墨烯（GO）片层彼此呈隔离依附状态的BEN/GO纳米复合粉末，然后将BEN/GO纳米复合粉末与PLA熔融共混，借助BEN粒子在PLA基体中的良好分散性，以BEN粒子为分散载体，将吸附在BEN粒子表面的GO片层良好分散在PLA基体中，制备出PLA/BEN/GO三元纳米复合材料。一方面，重点研究BEN粒子和GO片层在PLA基体中的分散机理，实现PLA/BEN/GO三元纳米复合材料的分散相微观形态调控；另一方面，从弹性体材料和塑料结晶改善两个角度，探讨BEN粒子和GO片层协同增韧PLA机理，以及BEN粒子提高PLA复合材料的生物降解性、GO提高PLA的结晶性、耐热性机制，为制备高性能PLA复合材料提供研究新思路。

提高聚乳酸（PLA）的韧性、结晶速率和耐热性而不牺牲其宝贵的生物降解性，具有重要的研究和应用价值。本项目首先制备了具有纳微米尺度的生物降解的辐射交联聚酯弹性体粒子（BEN）和氧化石墨烯（GO）片层彼此呈隔离依附状态的BEN/GO纳米复合粉末，然后将BEN/GO纳米复合粉末与PLA熔融共混，借助BEN粒子在PLA基体中的良好分散性，以BEN粒子为分散载体，将吸附在BEN粒子表面的GO片层良好分散在PLA基体中，成功制备出微观形态可控的PLA/BEN/GO三元纳米复合材料。BEN/GO复合粉末能显著提高PLA的韧性。PLA/BEN/GO三元纳米复合材料的断裂伸长率与缺口冲击强度分别达到了纯PLA的9.8倍与1.8倍，冲击断面形貌较为粗糙，应力发白现象明显，表现为塑性形变。PLA/BEN/GO三元纳米复合材料对应5%质量损失的分解温度较纯PLA提高了10.4°C。BEN能够改善PLA复合材料的结晶性能，缩短半结晶时间（t1/2），提高结晶度；BEN/GO复合粉末能够使PLA复合材料的球晶尺寸减小，加速结晶成核，且不会改变结晶结构和结晶机理，其半结晶时间较纯PLA缩短了19%，结晶度提高了0.18倍。BEN/GO复合粉末还能够提高PLA的导电与导热性能。在脂肪酶和土壤掩埋降解环境中，添加SBEN/GO-S（200 nm）的PLA/BEN/GO三元纳米复合材料的质量损失速率分别达到了纯PLA的11.3倍与8.3倍。细胞相容性实验表明，经PLA/BEN/GO三元纳米复合材料浸提液体外培养的细胞L929在24h与48h后的相对增殖率均高于75%，形态良好，毒性评级为一级合格状态，表明PLA/BEN/GO三元纳米复合材料属于无毒级别，具有良好的细胞相容性。