The Ultimate Biodegradation of The Starch Based Biodegradable Plastics

The objective of this work was to investigate the ultimate aerobic biodegradation of poly(lactic acid) (P LA) and poly(butylene adipate-co-terephthalate) (PBAT), with and without the starch according to 1S014855-1: 2004. The degree of biodegradation for 120 days of PLA, PLA/starch (50:50), PBAT and PBAT/starch (50:50) were 85.75%, 93.60%, 23.71% and 73.32%, respectively. The degree of biodegradation of cellulose was 70.20% under the same conditions. For PLA, a lag phase was observed during the first twenty days of the testing. This result indicated that there was no ultimate biodegradation occurred at the beginning of testing period of PLA. However, no lag phase was observed in the biodegrability testing of the PLA/starch (50:50), PBAT and PBAT/starch (50:50). Moreover, the addition of starch into the polymers leads to higher biodegradation rate of the materials. Finally, the biodegradation results were confirmed by thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). It was found that the results of TGA, FT-IR and SEM were in good accordance with the biodegradation results.