Processing of Plasticized Starch-Based Materials: State of the Art and Perspectives

Starch, as a natural polymer, can be processed by techniques such as extrusion into films/sheets, foams, shaped articles, etc. During processing, starch experiences a phase transition (gelatinization/melting) from native granular form to homogeneous molten form, which can be enhanced by shear treatment. The processing rheology of starch melt has a close relationship with thermomechanical input. Both phase transition and rheology play critical roles in starch processing and can be largely influenced by plasticizer type and content and starch type and structure (amylose/amylopectin ratios).Due to the inherent drawbacks of starch, starch-based blends (e.g., with biodegradable aliphatic polyesters) and (nano)composites (e.g., with cellulose or nanoclays) have been widely examined. The production of high-performance plasticized starch-based materials relies on the facility (extruder, die, takeoff device, etc.), sample preparation and processing strategies (plasticizer addition method, blending sequence, orientation, etc.), and the control of processing conditions (temperature, pressure, shear rate, etc.).