Résumé
The main drawbacks of protein-based bioplastics are a high sensitivity to water, insufficient mechanical properties, and a narrow window of processing conditions. The objective of this work was to study the effect of Kraft lignin (KL) on protein aggregation, functional, and rheological properties of fish protein (FP)-based bioplastic. FP powder was blended with 30% glycerol and 0-70% KL. Then, blends were thermoformed by compression molding. KL addition increased protein solubility in sodium dodecyl sulfate buffer, indicating a decrease of protein molecular weight. An introduction of KL in protein blend increased mechanical properties and decreased water absorption of materials. KL addition resulted in a decrease in storage modulus in rubbery state of protein blends. It also resulted in a decrease in viscosity of protein blends at processing temperature, as determined by capillary rheometry. Therefore, KL is an alternative additive to enlarge the protein thermal processing window and improve functional properties of FP-based materials. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013