Improving the Properties of Biodegradable PLA via Blending with Polyesters for Industrial Applications

Abstract

Polylactic acid (PLA) is a biodegradable polymer obtained from the fermentation of renewable resources, which can also be used in industrial areas. The employment of PLA is restricted by its brittle nature at room temperature. This study, it is aimed to prepare PLA blends with PBT (Polybutylene terephthalate) to overcome this drawback. Thus, it can be provided new raw materials to many sectors, especially textile, automotive and electronic products, by preparing biodegradable, environmentally friendly materials with better performance properties. PLA/PBT blends containing 5%, 10%, and 15% PBT by weight were produced in a twin screw extruder using with using maleic anhydride grafted ethylene/butyl acrylate (EBA-g-MAH) as a compatibilizer. For comparison studies, blends of PLA/PBT without compatibilizer were also prepared. Examinations on the flow, viscoelastic properties, and rheologic characteristics of prepared samples were carried out by using Melt Flow Index values and Rotational Rheometer measurements. Mechanical and impact resistance characteristics were identified in accordance with the relevant standards. Physical properties of blends such as molding shrinkage, density, and hardness values were also determined. Degradation or cross-linking-induced changes in the chain structure was not observed during the investigation via using a rotational rheometer for PBT samples at 240 °C /15 min., and PLA samples at 260 °C /15 min. Notched izod impact test results show that adding compatibilizer increases 16% impact resistance of PLA/PBT blends. The tensile modulus values of the blends containing compatibilizer decreased by 2% approximately. These results show the transition from brittle to ductile behavior of PLA for compatibilized blends.