Effect Of Storage Time, Plasticizer Formulation And Extrusion Parameters On The Performance Of Thermoplastic Starch Films

ALVAREZ, VERA ALEJANDRA; GUARAS, MARÍA PAULA; LUDUEÑA, LEANDRO NICOLÁS

Advanced materials letters

VBRIpress

Año: 2019 vol. 10 p. 206 - 214

0976-3961

A twin-screw extrusion processing method was developed for the preparation of thermoplastic starch (TPS)for packaging applications. Different plasticizer combinations were used looking for the minimal temperature profile in the extruder in order to prevent the thermal degradation of TPS. The effect of storage time at 25°C and 50% of relative humidity on the properties of TPSwas studied. Plasticized TPSsamples observed by scanning electron microscopy showed homogeneous fracture surfaces without unstructured starch granules. X-ray diffractometry tests showed retrogradation of all TPS formulations with progressive Vh-type crystal structure formation. Temperature for maximum thermal degradation rate of raw materials was shifted to higher values after preparing theTPS, suggesting not only physical but also chemical interactions between plasticizers and starch molecules. Mechanical properties were significantly improved replacing 10wt.% of glycerol by water as plasticizer, which was attributed to the increased gelatinization degree and the reduction of thermal degradation.