Since the 1950s, plastic production has steadily increased with millions of metric tons accumulating in the environment.1 Much of the waste stream is single use plastics, and the need for biodegradable alternatives is pressing. Polyhydroxyalkanoates (PHA), a class of polymers produced by many bacteria as a carbon source, presents a viable biodegradable replacement for many commodity thermoplastics such as polypropylene and polyethylene. Currently, extrusion processing of PHA requires rapid crystallization, and its use for many applications is hindered by a very slow crystallization rate, poor toughness, and low melt strength. The use of heterogeneous and melt miscible nucleating agents allows for the improvement of the crystallization rate of PHA that can be tailored to the desired processing conditions and end use application. While both chemical composition and proper crystallization greatly influence the mechanical properties of PHA, further advancements through melt blending with other biopolymers such as polybutylene succinate using twin screw extrusion are needed for a variety of applications.
1. Geyer, R.; Jambeck, J. R.; Law, K. L., Production, use, and fate of all plastics ever made. Science Advances 2017, 3 (7), e1700782.