Thermoplastic starch-silica-polyvinyl alcohol composites by reactive extrusion

Thermoplastic starch-silica (SiO2) PVOH composite films were created via a reactive extrusion process using tetraethyl orthosilicate (TEOS) as a precursor. Reaction efficiency was determined by X-ray fluorescence measurement of film Si content and was observed to improve with increasing TEOS concentration. Films with high SiO2 content were noted to have varying morphology and some SiO2 clusters. Mechanical properties of the starch composite films were enhanced by even a small amount of SiO2. Tensile strength and Young's modulus increased, while elongation at break decreased with increasing SiO2 content. Dynamic mechanical analysis results showed that the starch-silica composite storage modulus increased and the loss modulus decreased with increasing SiO2 content.