Abstract: The neat PLA was modified by chain extension and the influence of the chain extender on the rheological properties was investigated. Three chemical agents, foaming agent A (Masterbatch), foaming agent B（AC+NaHCO3）and foaming agent C (modified AC), were used to investigate the foamablibity of PLA. The density and cell morphology of extrusion foamed PLA were studied. It showed that the foamability of PLA was improved by adding the chain extender, which increased viscosity and decreased the melt flow rate. The foamability was best when the chain extender content was 0.8. The size, shape, density and distribution of the cells of the foamed PLAs were examined. The best foamed PLA was found with foaming agent C, with the density, cell diameter, and cell density being 0.6 g·cm-3, 57 μm, and 7.37×10^6 per·cm-3,respectively.

Key words: poly(lactic acid), chain extension, chemical foaming, extrusion, cell structure