The contribution of eco-friendly bio-based blends on enhancing the thermal stability and biodegradability of Poly(lactic acid)

Blends of PLA-NR with and without liquid natural rubber (LNR) as a compatibilizer were prepared using a melt blending process. Thermal stability and biodegradability properties of poly(lactic acid)-natural rubber (PLA-NR) blends were studied using thermogravimetric analysis and compost soil burial tests. The sample surface morphology after each burial cycle was observed by digital microscopy. Water absorption tests were also conducted to study the effect of water absorption on the sample degradation rate. The pure PLA sample exhibits no weight loss before day 150; however, the addition of NR causes a significant weight loss as early as day 30. Both NR and LNR effectively increased PEA degradation, with compatibilized blends at 8 wt% LNR degrading faster than uncompatibilized blends; these results are attributed to the high water absorption as well as poor adhesion between matrix. Meanwhile, the poor thermal stability of PLA improves greatly with the incorporation of both NR and LNR. Several factors such as water absorption and the adhesion between matrix may directly influence the thermal stability and biodegradability of the compatibilized PLA-NR blend. These comparative studies support a direct role of NR and LNR in PIA degradation properties. (C) 2018 Elsevier Ltd. All rights reserved.