Biodegradation of Wheat Straw/PLA Composites by Four Kinds of Microorganisms

Abstract

In order to compare the degradation of PLA composites by different microorganisms, and reveal the degradation mechanism. Actinomyces israelii, Aspergillus niger, Trichoderma harzianum and Phanerochaete chrysosporium were selected to degrade PLA composites. The weight loss, functional groups, thermal properties and crystallinity of the PLA composites before and after degradation were analyzed. The results indicated that A. israelii and A. niger had the strongest ability to degrade the composites, and the weight loss of the PLA composites reached 7.14% and 6.99% respectively after degradation for 28 days, which were significantly higher than that of the control treatment. According to the characterizations, it was found that the degradation was mainly hydrolysis by the microorganisms and their protease and lipase. Microbial degradation would lead to cracks and dents on the surface of the samples, and increase their contact area with microorganisms, thus accelerating the degradation rate. A. israelii and T. harzianum were more inclined to degrade the PLA in the composites during microbial degradation. Microbial degradation destroyed the crystalline region of the composites, which made they easier to degrade. The results would be helpful to explore the microbial degradation mechanism of PLA composites, and promotes its application in different fields.

Keywords

• biodegradable polymer
• pla composites
• degradation
• microorganisms
• actinomyces israelii
• aspergillus niger
• trichoderma harzianum
• phanerochaete chrysosporium