Epoxy functionalized poly(lactide) reactive modifier for blown film applications

Epoxy functionalized poly(lactide) (EF-PLA) was synthesized by reacting PLA with a multifunctional epoxy polymer (MEP) using reactive extrusion processing. These polymers can function as a rheology modifier for PLA and a compatibilizer for other biopolyesters in blown film and foam applications. Model compound studies show that the epoxy functional group on the MEP reacts selectively with the carboxylic acid chain-ends of PLA at processing temperatures below 200 degrees C. An EF-PLA containing up to 10% MEP was prepared without gel formation and reactively extruded with neat PLA to obtain three different product formulations containing MEP (0.25, 0.5, and 1.0%). These products showed significantly enhanced rheological properties compared to what has been reported by other groups and is currently used in the PLA blown film industry, the blending of MEP with PLA in a single step. These benefits are a result of how the MEP gets distributed in the material, and can lead to improved properties even at lower MEP concentrations. Our new materials showed significant strain hardening rheological behavior demonstrating that they can be readily blown into films and foams. A statistical simulation was developed to provide a fundamental understanding of the reaction as well as provide information on the molecular weight characteristics and reactivity of the EF-PLA. The EF-PLA molecule shows good potential for use as a rheology modifier and compatibilizer. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42243.