Preparation And Performance Study Of Poly (Lactic Acid)(PLA)/ Modified Microfibrillated Cellulose(MFC) Composite Material

Poly (lactic acid) (PLA) as a biodegradable materials from green resource which has high strength and modulus, widely used in the packaging, construction, agriculture, transportation and electronic industry. However, the drawback of high cost,brittleness, low crystallization rate limited its applications. Based on previous studies, microfibrillated cellulose(MFC) was choosen to compound with PLA to improve its mechanicl property and crystallizaton in present study.Firstly, Microfibrillated cellulose (MFC) was modified by acylation to improve the dispersion of MFC in the weak polar solvent or polymer matrix. And the effect of reaction time on the acylation had been investigated. The nucleating and reinforcing effect of the modified MFC(MMFC)with different reaction time in PLA matrix had also been investigated. The results showed that after acylation, the dispersion of MMFC in chloroform solvent improved significantly and the degree of substitution(DS) of MMFC first increased significantly with the acylation reaction time increased then tend to eased. The nucleation and enhancement of MMFC in PLA matrix improved significantly when acylation reaction time was shorter then 2h, but decreased significantly when acylation reaction time longer then 4h. In general, in order to get the best nucleation and enhancement, the acylation reaction time was 2h.Then, different mass ratio of MMFC/PLA composites were prepared, and the mechanical properties and melt crystallization behavior of the composites were investigated. The results showed that MMFC played a significant role in enhancement and nucleation in PLA matrix. After added MMFC, the mechanical properties, crystallinity and crystallization rate of the material improved significantly.3wt% MFC of PLA composites and 3wt% MMFC of PLA composites were prepared to investigated the effect on nucleation and enhancement of acylation. After acylation, the dispersion of MMFC in PLA matrix was improved, and the nucleation and enhancement of MMFC improved significantly.In order to further improve the toughness of PLA materials, PLA/MMFC/EGMA composites were prepared.In the ternary system, MMFC and EGMA dispersed in the PLA matrix evenly, and EGMA and MMFC improved the material’s crystalline ability and toughness synergistically.