Slit die rheology of thermoplastic starch during extrusion process

Abstract

In this work, the rheological properties of thermoplastic starch (TPS) were determined using a laboratory scale single screw extruder at different temperatures (110, 130, and 140 °C) and speeds (10, 15, 20, 25, 30, and 35 RPM). Glycerol was used as a plasticizer for preparing TPS. Apparent shear rate ( $$ {{\mathop{\gamma}\limits^{\cdot}}_a} $$ ), apparent shear stress (τ a ), apparent shear viscosity (η a ) and flow activation energy at a constant shear rate (E γ ) were determined. The results showed that TPS melts were pseudo plastic (n < 1) and the shear viscosity decreases with increasing shear rate at different temperatures. Also it was found that that shear viscosity of TPS decreases with increasing glycerol content in TPS, according to the values of flow activation energy at a constant shear rate, TPS25 was more sensitive to processing temperature.