Self-reinforced biodegradable thermoplastic composites

Abstract

Improvements in the mechanical performance of biodegradable plastics are required to facilitate replacement of commodity plastics as part of a global push for the use of more sustainable materials. Reinforcing biodegradable plastics with fillers or fibres to create composite materials is an obvious choice for increasing mechanical properties but may affect recyclability and biodegradability. To avoid these issues, self-reinforced polymer composites (SRPCs), where the polymer matrix is reinforced with highly oriented films, fibres, or particles of the same polymer may be used. However, the use of biodegradable thermoplastics in SRPCs is currently limited to a few polymers, mostly focusing on poly(lactic acid) (PLA). Here, we have assessed the potential for a broader range of biodegradable thermoplastics to replace commercially available commodity-plastic-based SRPCs. This assessment was done using literature data for the oriented and isotropic bulk mechanical properties of commercially relevant biodegradable thermoplastics, along with properties for their SRPCs where available. It was found that despite polycaprolactone (PCL), poly(butylene succinate) (PBS), poly(butylene succinate adipate) (PBSA), and poly(butylene adipate terephthalate) (PBAT) not being suitable replacements for current commercially available SRPCs, they nonetheless exhibit increased modulus and strength after orientation. PLA, polyhydroxyalkanoates (PHAs), and poly(glycolic acid) (PGA) have more potential, with PGA being the most promising, although PLA and PHAs appear to offer potentially more sustainable alternatives to commercially available SRPCs and a wider range of end-of-life disposal options.