Tapioca/polyvinyl alcohol thermoplastic starch materials processed with the aid of supercritical CO2

•Supercritical-CO2 (scCO2) was used to prepare thermoplastic starch (scCO2TPS).•ScCO2TPS was modified with polyvinyl alcohol (PVA) to prepare scCO2TPSxPVA05y.•Processibility and moisture-resistance for scCO2TPSxPVA05y were improved considerably.•More dissociated amylopectin chains were found for scCO2TPSxPVA05y.•Melt-temperatures of aged ScCO2TPSxPVA05y were ∼ 40 °C lower than that of TPS. This paper represents the first report of polyvinyl alcohol (PVA) modified TPS resins (scCO2TPSxPVA05y), gelatinized and/or modified with the aid of supercritical carbon dioxide (scCO2). The melt flow rate, initial and retention values of tensile strength (σf) of scCO2TPSxPVA05y prepared with the aid of both scCO2 and PVA05 were considerably higher than those of the corresponding scCO2TPS prepared using scCO2 fluid and/or TPSxPVA05y materials prepared in the conventional way. The moisture contents of conditioned scCO2TPSxPVA05y were considerably lower than those of the corresponding scCO2TPS and TPSxPVA05y aged for the same amounts of time. Conditioned scCO2TPSxPVA05y exhibited only Vh-type crystals with melting temperatures ∼ 40 °C and ∼ 20 °C lower than those of corresponding conditioned TPS and TPSxPVA05y, respectively. In comparison to TPS and TPSxPVA05y, more dissociated amylopectin chains with loosely hydrogen-bonded −OH groups and significantly less retrogradation was obtained for conditioned scCO2TPS and scCO2TPSxPVA05y, respectively.