How does a chain-extended polylactide behave?: a comprehensive analysis of the material, structural and mechanical properties

Abstract

The presented contribution deals with the material properties of chain-extended polylactide. In the course of this study, two different functional additives were used, namely an epoxidized and a maleated styrene-acrylic copolymer. Both additives were compounded together with polylactide using a conventional twin-screw extruder, and were then injection moulded to standardized testing specimens. The main focus of the investigation is on structural changes as well as the mechanical performance, e.g. crack propagation and arresting mechanisms that are affected by reactive chain extension. The first section of the experimental part consists of results regarding modifications achieved on the macromolecular level. Based on size exclusion chromatography and DSC-OIT experiments, different structural changes and their influence on the material behaviour are presented. Subsequently, a comprehensive analysis of the quasi-static tests and the impact strength of notched and unnotched specimens was performed, and correlated with the following fatigue experiments. A discussion concerning morphological aspects and finally a correlation to the fracture surface topography after fatigue test completes the experimental part.