Recent advances on reactive extrusion of Poly(lactic acid)

Poly(lactic acid) (PLA) is a bio-based, bio-compostable and bio-compatible aliphatic polyester which derives from lactic acid. The interest for this bioplastic has increased in the last decade, as search for alternatives to oil-based plastics such as poly(ethylene) and poly(styrene), becoming compelling. PLA can be manufactured via two different routes: poly-condensation or ring-opening polymerization. The latter has been conducted successfully in combination with reactive extrusion (REX) to produce high molecular weight poly(L-lactide) (PLLA) with good mechanical properties. Reactive extrusion is a "green" process, which allows for continuous production without the use of toxic organic solvents. This technique can be paired with in situ chemical modification of PLA and compatibilization with other polymers. This includes the formation of copolymers, branched PLA and composites. The aim of this review is to provide an update on the last eight years of research dedicated to reactive extrusion applications on PLA.