Anaerobic Biodegradation of a Poly (lactic acid) Blend Containing a Poly (lactic acid)-Co-Poly (glycolic acid) Copolymer

Plastics usage is ever increasing due to its many advantages over competing materials including low cost, low density and ability to be converted into useful objects. However, the inability of traditional plastics to degrade results in the accumulation of large amounts of waste. Though recycling remains an attractive option for many applications, mixed waste streams containing plastics co-mingled with other waste types (e.g. food waste) require separation and cleaning steps that renders this option less attractive. Biodegradable plastic materials may offer a solution to this problem providing alternative end-of-life scenarios (e.g. compositing and anaerobic degradation). Unfortunately, many of these materials still exhibit slow degradation kinetics thus limiting this option.

The goal of this work is to examine the anaerobic biodegradation of polylactic acid (PLA) blended with a highly, degradable poly(lactic acid-co-glycolic acid) (PLGA) copolymer. In this experiment both blend composition and PLGA molecular weight were varied. PLA and PLGA were found to be miscible over the molecular weight and blend ratio ranges investigated. The rate of methane production increased with PLGA content in the blend and this was particularly pronounced at early stages of the anaerobic degradation process. Moreover, the rate of methane production increased as PLGA molecular weight decreased. It is envisioned that this strategy could be applied to improve the efficiency of the anaerobic degradation of waste stream containing single-use plastics co-mingled with food waste.