Improving the Properties of Polylactic Acid by Blending With Low Molecular Weight Polylactic Acid-g-Natural Rubber

The low molecular weight (M-w) polylactic acid-g-natural rubber (PLA-g-NR) was synthesized by grafting the maleated natural rubber (MNR) with low molecular weight PLA at a weight ratio of 1:1 in toluene at 80 degrees C. Two types of MNR (MNR10 and MNR20) having anhydride moieties of 10 and 20 wt%, respectively, were prepared. The reaction was followed by IR analysis. Next, the obtained PLA-g-NR was blended with pristine PLA using a twin-screw extruder at PLA to PLA-g-NR weight ratios of 90:10, 80:20, 70:30, and 60:40 followed by compression to obtain specimens for testing. In case of 10 wt% PLA-g-NR having MNR10, it was found that blending of PLA with PLA-g-NR resulted in a 200% improvement in impact strength and twofold percent elongation at break (flexibility). Further SEM analysis confirmed that PLA-g-NR was compatible with PLA matrix. In contrast, NR was present as disperse particles which exhibited poor adhesion to PLA. From these findings, it was also found that PLA-g-NR was capable of improving the properties of PLA more than NR due to the fact that it exhibited higher compatibility. POLYM. ENG. SCI., 54:2770-2776, 2014. (c) 2013 Society of Plastics Engineers