Effect of Natural Weathering Ageing on Mechanical Properties of Virgin and Recycled Polylactic Acid

Abstract

Due to a huge usage of plastics in the packaging industry, an abundant of plastics wastes is dumped at landfills. The environmental issue has given a serious impact to wildlife and humans. Hence, it is strongly advised to substitute the petroleum-based plastics with other plant-based polymers. One of the most popular bioplastics is polylactic acid (PLA). PLA can be biodegraded and recycled. The aim of this work is to investigate the effect of natural weathering ageing on the mechanical properties of virgin and recycled PLA. The investigation was focused on the tensile strength, transverse rupture strength (TRS) and impact energy. The samples were produced using the injection molding process. The samples were exposed to natural weathering continuously for 150 days. The sample inspection was monitored for every 30 days. The results showed that a decreasing in tensile strength of the recycled PLA was faster as compared to the virgin PLA. After 150 days exposed in natural weathering, there is about 41% reduction in the tensile strength of the recycled PLA. As for virgin PLA, the tensile strength is reduced approximately 11%. Similar trend was observed on the transverse rupture strength. The TRS for virgin PLA has dropped almost 14%. On the other hand, the TRS for recycled PLA declined at 17%. The diminishing in impact energy is more significant where it reduced 56% and 73% for virgin PLA and recycled PLA, respectively.