Converting Polysaccharides into High-Value Thermoplastic Materials

Modified starches including starch esters, pregelatinized Tapioca dextrin, and hydroxyalkylated starch were converted into thermoplastic materials. It was found that the rheology of thermoplastic modified starch (TPMS) was dependent on the type of modified starch, the type of plasticizers, and the amount of plasticizers present in TPMS. For the same modified starch, glycerol was a more effective plasticizer than sorbitol. The melt viscosity decreased as the amount of plasticizer amount increased. Binary polymer blends of TPMS and a biodegradable aliphatic-aromatic copolyester exhibited good film-forming properties and good water dispersibility, however, the mechanical properties of the films were poor. The binary polymer blend films had a laminar, layered microstructure. It was found that tertiary polymer blends comprising a majority of TPMS, a polyvinyl alcohol, and a biodegradable copolyester had good and balanced mechanical properties, film processability, and water dispersibility. The resulting water-soluble films had a high renewable content and properties needed for high-value, water-dispersible films.