Lifetimes of biodegradable plastics in natural and engineered environments

Aphra Agaba

School of Chemical Engineering, The University of Queensland

Conventional plastics have become an integral part of modern daily life due to their unique properties, such as low cost, durability over metal, wood, ceramics. Industrial sectors such as medical, packaging, agriculture, construction are some of the areas where plastic is ubiquitous. However, to achieve the desired plastic properties for the various applications, additives which are at times toxic are incorporated during the manufacturing process. The fate of these plastics in the environment was never seriously considered when they were first introduced, resulting in accumulation over time due to very slow degradation. As a result, the environment faces a significant threat of plastic pollution due to the vast amount of globally distributed plastic waste that is associated with hazardous chemicals such as additives, monomers.

Biodegradable plastics such as polyhydroxyalkanoates (PHAs) are potential sustainable alternatives to conventional counterparts due to their ecofriendly attributes, including biodegradability in a wide range of environments. Despite the numerous attributes, their wide application has been mainly hindered by inherent issues such as poor mechanical properties. To tackle this challenge, several strategies have been developed to enhance properties by blending with flexible and ductile materials, including the use of different additives. The key to sustainability lies in the careful selection of compatible materials/additives that are non-toxic, can improve mechanical properties, and that do not inhibit biodegradation.

This research project aims to understand the effect of some of the recommended additives on biodegradation of biodegradable plastics. The findings of this study are anticipated to inform the sustainable additives for biodegradable plastics. This evidence can contribute to safer plastic production using sustainable materials and this is significant towards minimising public health concerns, detrimental environmental and ecological footprint associated with plastics.