Rheology and processing of gluten based bioplastics

Knowledge of processing effects on the rheological properties of wheat gluten based biomaterials is important for the optimization of the productive process and to obtain biomaterials with suitable mechanical properties. In this paper, the linear viscoelasticity behaviour of glycerol/gluten bioplastics obtained by casting and thermoplastic processing has been studied. The effects of plasticizer content, mixing speed and thermal history were evaluated by oscillatory shear experiments and modulated differential scanning calorimetry in a wide range of temperatures. The mechanical spectrum of these materials was characterized during processing, showing a similar microstructure and, therefore, rheological behaviour at room temperature for both processing procedures. However, bioplastic obtained by mechanical processing showed higher thermal susceptibility, which was related to the denaturation degree and thermosetting and cross-linking potentials of proteins. (c) 2005 Elsevier B.V. All rights reserved.