Effect of citric acid on thermal, phase morphological, and mechanical properties of poly(l-lactide)-b-poly(ethylene glycol)-b-poly(l-lactide)/thermoplastic starch blends

This work investigated the thermal, morphological, and tensile properties of poly(l-lactide)-b-poly(ethylene glycol)-b-poly(l-lactide) (PLLA-PEG-PLLA)/thermoplastic starch (TPS) blends with 3 wt% citric acid (CA) treatment of TPS. The blends with PLLA-PEG-PLLA/CA-TPS ratios of 100/0, 90/10, 80/20, and 60/40 (w/w) were investigated and compared with PLLA-PEG-PLLA/CA-free TPS blends. Crystallizability of the blends decreased and thermal stability increased as the TPS content increased. The thermal stability of the blends was found to improve after CA treatment of TPS. The PLLA-PEG-PLLA/CA-TPS blends showed better phase compatibility than those of the PLLA-PEG-PLLA/CA-free TPS blends. The tensile properties of the blends were improved by CA treatment of TPS. In conclusion, improvement in thermal stability, phase compatibility, and tensile properties of the PLLA-PEG-PLLA/TPS blends was obtained by CA treatment of TPS. The resulting PLLA-PEG-PLLA/CA-TPS blends could potentially be used to prepare biodegradable and flexible bioplastics