Chemistry

Materials science

Plastic pollution

Microplastics

Biodegradable plastic

Environmental pollution

Anaerobic digestion

Methane

Engineering

Composite material

Biodegradation

Polycaprolactone

Environmental protection

Organic chemistry

Bacteria

Pulp and paper industry

Biology

Environmental chemistry

Polylactic acid

Thermoplastic

Plastic waste

Bioplastic

Polyhydroxybutyrate

Environmental science

Adipate

Biodegradable polymer

Polymer

Genetics

Waste management

Environmental Science & Technology

Plastic waste pollution is a global environmental problem which could be addressed by biodegradable plastics. The latter are blended together to achieve commercially functional properties, but the environmental fate of these blends is unknown. We have tested neat polymers, polylactic acid (PLA), polyhydroxybutyrate, polyhydroxyoctanoate, poly(butylene succinate), thermoplastic starch, polycaprolactone (PCL), and blends thereof for biodegradation across seven managed and unmanaged environments. PLA is one of the world's best-selling biodegradable plastics, but it is not home compostable. We show here that PLA when blended with PCL becomes home compostable. We also demonstrate that the majority of the tested bioplastics and their blends degrade by thermophilic anaerobic digestion with high biogas output, but degradation times are 3-6 times longer than the retention times in commercial plants. While some polymers and their blends showed good biodegradation in soil and water, the majority of polymers and their blends tested in this study failed to achieve ISO and ASTM biodegradation standards, and some failed to show any biodegradation. Thus, biodegradable plastic blends need careful postconsumer management, and further design to allow more rapid biodegradation in multiple environments is needed as their release into the environment can cause plastic pollution.

Biodegradable Plastic Blends Create New Possibilities for End-of-Life Management of Plastics but They Are Not a Panacea for Plastic Pollution