Studies on Processing Rheological and Mechanical Properties of Poly(lactic acid)/Sesbania Gum/Nano-silica Composites

Abstract

Processing rheological properties of poly(lactic acid) (PLA)/sesbania gum (SG)/nano-silica composites were investigated with a torque rheometer, and mechanical properties were researched by a universal testing machine and a cantilever-beam impact testing machine. Effects of SG content, nano-silica content, the types of plasticisers, the plasticiser content and the rotor speed of a torque rheometer on the properties of composites were discussed. The results indicated that polyethylene glycol (PEG)20000 exhibited the best plasticising effect on the composites, and at the same time, did not increase energy consumption of the systems compared with other four plasticisers. As for the aspect of processing rheological properties, the optimum formulation for PLA/SG/ nano-SiO2/PEG20000 composites was: 100 parts of PLA, 8 parts of SG, 2 parts of nano-SiO2, and 5–10 parts of PEG20000. Comparing with unmodified PLA, the comprehensive mechanical properties of the composites improved greatly, based on the results of the tensile, impact and bending tests.