Microcellular Extrusion-Foaming of Polylactide with Chain-Extender

The effects of adding epoxy-functionalized chain-extender (CE) and processing conditions such as die temperature on the cell morphology, volume expansion ratio (VER), open cell content (OCC), and crystallization of microcellular extruded polylactide (PLA) were investigated. When compared with pure PLA, the addition of talc decreased the average cell size and increased the cell density. Moreover, the simultaneous addition of talc and CE led to denser and more uniform cell structure up until 1.0% CE content. In general, the volume expansion ratio and open cell content of all the formulations decreased with the die temperature. The addition of talc decreased both VIER and OCC, whereas the addition of CE increased both. The die temperature did not affect the degree of crystallinity significantly. The addition of talc increased the crystallinity, but the addition of CE decreased it. Finally, the molecular weight of PLA increased significantly with the addition of CE. POLYM. ENG. SCI., 49:1653-1660, 2009. (C) 2009 Society of Plastics Engineers