Preparation, microstructure and performance of poly (lactic acid)-Poly (butylene succinate-co-butyleneadipate)-starch hybrid composites

Abstract Poly (lactic acid) (PLA)-poly (butylenesuccinate-co-butyleneadipate) (PBSA)-starch hybrid composites were developed, in which PBSA was used to improve mechanical and thermal properties while starch was used to decrease the cost of PLA and PBSA. To minimize the decomposition of PLA and PBSA during thermal processing, the hybrids sheets were prepared by one-step extrusion through connecting a twin screw extrude with a single extrude fitting a sheet die. The hybrid composites were characterized and observed that: (a) the one-step extrusion technology distributed starch granules into PLA/PBSA matrix homogeneously with minimizing the decomposition of polyester and the energy input decreased about 35% comparing with two-step extrusion, where the tensile properties by one-step were improved about 15–20% and impact strength was increased about 30%; (b) addition of starch granules, as fillers, deteriorated the continuous structure of polyester matrix due to poor compatibility between hydrophilic starch and hydrophobic polymer PLA/PBSA matrix. However, stearic acid acting as a surface modifier increased the compatibility between starch fillers and polymeric PLA/PBSA matrix and further improved the mechanical properties of the hybrids. PLA/PBSA-based hybrid composites filled with 30–40 wt % starch provided an acceptable balance between cost and performance of PLA-based materials.