Role of maleic- anhydride-grafted- polypropylene in supercritical CO2 foaming of poly (lactic acid) and its effect on cellular morphology.

Poly (lactic acid)/maleic-anhydride-grafted-polypropylene (PLA/MAPP) blends were prepared by melt blending method. The effect of MAPP content on the dispersion morphology, thermal properties, and rheological behavior of PLA/MAPP blends was studied. Then PLA/MAPP blends were foamed using supercritical CO2 as physical blowing agent; and the cellular structure, cell size, as well as cell density were investigated. The results showed that of MA reacted with PLA, and thus a small amount of branched polymer would be formed. The branching structure strongly affected the rheological behavior, as well as the thermal properties of PLA. The blending morphology of PLA/MAPP blends also had a significant effect on the cell density of all the samples. The results indicated that homogeneous and finer cellular morphology for PLA/MAPP foams with high expansion ratio could be achieved with a proper content of MAPP in the blends. [ABSTRACT FROM AUTHOR]