Preparation, Property and Morphology of Thermoplastic Starch

Thermoplastic starch was prepared from corn-starch in a batch-mixer in the presence of glycerol, urea and water. The effects of glycerol and urea amounts on the plasticity of thermoplastic starch were studied. The crystallinity change of starch samples was studied by XRD. The results showed that the crystalline structure of the starch was destroyed during processing, and an easy processing thermoplastic starch was obtained. The crystallinity of thermoplastic starch decreased with the increase of urea amount. Increasing glycerol amount results in the loss of tensile strength, but the enhancement of elongation at break of the product. When the mass ratio of glycerol to starch was 0.20～0.40, the apparent viscosity decreased with increase in glycerol amount, and all of the thermoplastic starches become pseudoplastic fluids. The thermoplastic starch exibited better biodegradability than news paper. The thermoplastic starch/polyethylene blends can be blown into transparent films.