Improving the Properties of the Biopolymer Poly(Lactic Acid)

Poly(Lactic Acid) PLA is a thermoplastic biopolymer manufactured by several commercial processes using lactic acid derived from the fermentation of carbohydrates.  PLA has a melting point range of 170° to 207°C and is currently being used in “green-based” film and food packaging as a biodegradable alternative to oil-based polymers.  However as with oil-based polymers, Poly(Lactic Acid) requires improvement in its melt rheology to address the challenging manufacturing processes of thermoforming, sheet extrusion, film, fiber forming and injection molding.  In this technical paper we consider two different approaches for improving the processability and performance of PLA.  The use of certain acrylic based core-shell impact modifiers has been found to both toughen and significantly improve processability of PLA. The melt viscosity of this biopolymer can also be improved by reactive processing with select organic peroxides to increase branching and/or molecular weight.