Effects of Long Chain Cellulose Ester on Mechanical Properties of Polylactic Acid Reinforced with Microcrystalline Cellulose

Abstract

Long chain cellulose ester (LCCE) synthesized by acylation reaction via microwave process was used as a compatibilizer for banana stem microcrystalline cellulose/polylactic acid (BS MCC/PLA) composite. The proper reaction time and power output for LCCE synthesis were 150 second and 160 watt, respectively, which resulted in the highest weight increase (%) of LCCE synthesis. The FT-IR and NMR results confirmed that long chain acyl ester was grafted on cellulose structure. The degree of substitution (DS) of LCCE was 2.41. The BS MCC content was fixed at 40wt% while LCCE content was varied from 0-9 wt%. The Tensile properties properties of BS MCC/PLA composites with or without LCCE were studied by tensile test. The results revealed that the addition of LCCE enhanced the elongation at break of 40wt% BS MCC/PLA composite owing to the improvement of compatibility between PLA and MCC, particularly the addition of 5wt% of LCCE which led to the highest elongation at break. However, when the addition of LCCE was greater than 5wt%, the elongation at break was slightly decreased because of the small aggregation of BS MCC and LCCE in PLA matrix as supported by morphological analysis. Nevertheless, the addition of LCCE contributed to the decrease in tensile strength and Young’s modulus of 40wt% BS MCC/PLA composite slightly because of the decreasing of crystallinity in PLA composite.