Modification of poly(lactic acid)/poly(propylene carbonate) blends through melt compounding with maleic anhydride

Maleic anhydride (MA) is incorporated into poly(lactic acid) (PLA)/poly(propylene carbonate) (PPC) blends to modify its properties through melt compounding. It is interesting to note that the toughness of PLA/PPC blends can be improved by 1355% while the strength is almost kept constant by adding very low content (as low as 0.9%) of MA into the blends. However, higher MA content in the blends leads to decrease in strength and further increase in toughness indicating an obvious plasticizing effect, while MA is shown to have no effect on the toughness of neat PLA. Rheological, scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA) studies have been carried out to understand the above results. It is believed that the improvement in mechanical performance originated from the largely retained molecular weight of PPC and improved interfacial interaction after processing. And relative large amount of MA in the blends is shown to mainly plasticize the PPC phase rather than the PLA phase. Such an effective method could provide PLA based biodegradable polymer blends with novel properties for industrial applications.