Mathematical modeling and experimental validation of an extrusion process to produce biodegradable cassava starch pellets

Abstract

The development of materials that can cause less impact for the environment has been considered a subject of great importance nowadays. The knowledge of efficient techniques for the production of these materials is fundamental. The extrusion process is an example of efficient technique, with the advantage of being a continuous process as well, although the definition of the optimal process parameters is not simple. Therefore, the project aims to study an extrusion process by developing and validating an analytical model that simulates the production of biodegradable cassava starch pellets, which would be used to produce films for packaging. Moreover, it is important to seek the optimal process parameters, considering the greater efficiency. The equipment used is a co-rotating twin-screw extruder and it is widely used to extrude temperature-sensitive materials. During the extrusion, physical and chemical modifications occur within the material due to the thermal and mechanical treatment that it suffers (reactive extrusion). Therefore, for modeling, the extruder is considered a reactor in which differential balance equations of mass, momentum, and energy will be developed to describe the process properly. Computational Fluid Dynamics (CFD) will be used to simulate the process and define the ideal temperature profile in the sections after the material changes its state to a fluid. In addition, a crucial step will be the determination of residence time and material rheology parameters (the apparent viscosity of the fluid and the specific mechanical energy in the process) to better understand the fluid behavior considering the temperature changes during the process and to adjust the model with experimental data. Furthermore, it will be executed a step to validate the model, in which extrusion tests will be performed with the material, aiming the scale-up of the production. Finally, qualitative and quantitative analyses will be done on the extruded material. (AU)