Application of extrusion-cooking for processing of thermoplastic starch (TPS)

Thermoplastic starch (TPS) as fully biodegradable biopolymer appeared to be one of the most useful and promising materials for packaging purpose. To obtain TPS thermal and mechanical processing should disrupt semi-crystalline starch granules. As the melting temperature of pure starch is substantially higher than its decomposition temperature, there is a necessity to use plasticizers, e.g. a glycerol. Various blends of potato starch mixed with glycerol were extrusion-cooked to obtain different range of TPS pellets, then processed using film blowing and injection molding techniques. Starch modification under high temperature, glass transition temperature, visco-elastic properties of TPS samples (DMTA), the storage modulus E′ and loss modulus E″ were evaluated for several frequencies. The mechanical properties, the texture and the structure of the obtained materials were measured using standard methods. ► We investigated potato starch-glycerol-water mixtures for thermoplastic starch (TPS). ► Extrusion-cooking was applied for TPS pellets processing. Injection moulding was used for biodegradable dog-bone specimen preparation from TPS. ► TPS biodegradable film was prepared with film blowing extruder. ► Starch melting, DSC, mechanical properties and microstructure of TPS were tested.