Effect of Compatibilization on poly-ε-caprolactone grafting onto poly(ethylene-co-vinyl alcohol)

Abstract

The non-miscibility of the reactants during solvent free poly-ε-caprolactone grafting onto poly(ethylene-co-vinyl alcohol) (EVOH) dramatically affects reaction kinetics. Different solutions were proposed to accelerate the exchange reactions between poly(ethylene-co-vinyl alcohol) and poly-ε-caprolactone. Reactions were conducted in a batch reactor or a mini twin-screw extruder. The addition of a poly(ethylene-co-vinyl alcohol)-g-poly-ε-caprolactone copolymer increased the compatibility of the reactants and led to a higher reaction rate. This copolymer was either prepared separately and added at the reaction beginning or prepared in situ grafting caprolactone from EVOH. The reactive system evolution was analyzed using molar mass evolution, microstructure characterization, thermal properties and the reactive blend morphology. The compatibilization effect combined with optimized reaction conditions, such as concentration and nature of catalyst and temperature, resulted in an important increase in reaction rates. Among the tested catalysts, 1,5,7-Triazabicyclo [4.4.0]dec-5-ene was a more efficient catalyst for grafting reactions than Tin (II) 2-ethylhexanoate. © 2011 by the authors; licensee MDPI, Basel, Switzerland.