Injection moldings of micro fibrillated cellulose reinforced biodegradable PLA

最近，“绿色复合材料”的重点是由植物纤维和生物基树脂制成的材料。植物纤维不仅可再生，而且与制造FRP（纤维增强塑料）常用的玻璃纤维相比，具有低密度和高强度。因此，纳米植物纤维被认为是一种潜在的增强材料。木浆纤维（微纤化纤维素，MFC）的纤颤是获得纳米植物纤维的途径之一。利用植物纳米纤维作为增强材料，大大提高了复合材料的力学性能和热性能。在这些研究的基础上，本项目研究了MFC增强可生物降解PLA注塑成型的生产。本研究的主要目的是通过熔融混合法制备纤维化木浆/聚乳酸纳米复合材料，并保证其注塑成型的潜力。将MFC与PLA在溶剂中进行预混，制备出分散性较好的纤维复合材料，其强度和杨氏模量均优于纯PLA。发现MFC的表面乙酰化可以有效地增加纤维素纳米纤维与PLA之间的相互作用力。在PLA中加入5 wt%的乙酰化MFC， PIA的杨氏模量和拉伸强度分别提高了25%和15%。最后，我们成功地注塑成型了MFC增强PIA，与纯PIA成型相比，它具有优异的热稳定性。

Recently 'green-composites' have been focused on materials made from plant fibers and bio-based resins. Plant fibers are not only renewable but also have low density and high strength when compared to glass fibers, which are in common use for making FRP (Fiber Reinforced Plastics). Hence, nano-sized plant fibers are recognized as a potential reinforcing material. Fibrillation of wood pulp fibers (microfibrillated cellulose, MFC) is one of the ways to obtain nano-sized plant fibers. There are many reports describing that mechanical and thermal properties of composites are highly enhanced by utilizing such plant nanofibers as reinforcing material. On the basis of these researches, in this project, we studied the production of MFC reinforced biodegradable PLA mouldings by injection mouldings. The main purpose of this research is to obtain fibrillated wood pulp/PLA nanocomposites by the melt-mixing method and to assure the potential of the nanocomposites for injection moulding.By premixing MFC and PLA in the solvent, we could make well dispersed fiber composites and improve strength and Young's modulus of the composites over the neat PLA. Surface acetylation of MFC was found to be effective to increase interactive forces between cellulose nanofiber and PLA. The addition of acetylated MFC to PLA by 5 wt% improved the Young's modulus and tensile strength of PIA by 25% and 15%, respectively.Finally, we, have succeeded in the injection moulding of MFC reinforced PIA, which showed excellent thermal stability compared to neat PIA mouldings.