Effects of silica on the morphology, structure, and properties of thermoplastic cassava starch/poly(vinyl alcohol) blends

Thermoplastic cassava starch (TPS)/poly(vinyl alcohol) (PVA)/silica (SiO2) composites were prepared by a melt-mixing method. The effects of the content and surface properties of SiO2 on the processing, mechanical properties, thermal stability, morphology, and structure of the TPS/PVA/SiO2 composites were investigated. With increasing SiO2 content, the plasticizing times of the TPS/PVA/SiO2 composites were shortened. After the SiO2 surface was treated with a silane coupling agent (KH550), the plasticizing times of the TPS/PVA/SiO2 composites decreased significantly. The tensile strength, elongation at break, and Young's modulus of the TPS/PVA/SiO2 composites increased. The mechanical properties of the TPS/PVA/SiO2 composites containing treated SiO2 were higher than those with untreated SiO2. The thermal decomposition temperatures of the TPS/PVA/SiO2 composites were improved with the addition of SiO2. The presence of inorganic fillers was beneficial to the improvement of the thermal stability of the polymers. The reaction between the treated SiO2 and the starch molecules was beneficial to the formation of more stable structures. The treated SiO2 indicated good interfacial adhesion and uniform dispersion in the matrix. (C) 2016 Wiley Periodicals, Inc.