Upsized Vortex Fluidic Device Enhancement of Mechanical Properties and the Microstructure of Biomass-Based Biodegradable Films

Abstract

A process for fabricating biodegradable polymer films from renewable feedstocks, namely, agar, alginate, and glycerol, with enhanced mechanical properties has been developed. A critical step in the process involves use of high shear stress and micromixing in a liquid thin film in an energy-efficient upsized vortex fluidic device (VFD) operating under confined-mode conditions. The upsized VFD having a 50 mm-OD diameter tube titled at 45° requires a fraction of the processing time and energy consumption relative to the standard VFD having a 20 mm-OD diameter tube titled at the same critical angle. It also overcomes difficulties of jet feed blockage and excessive gelling close to the base of the rapidly rotating tube for the high-viscosity liquid mixture when it is processed in the standard VFD operating under continuous flow for throughput competitive comparison. The enhanced mechanical properties of the polymer films (e.g., 0.14 strain) relates to the formation of a uniform solid inner microstructure and a smoother surface devoid of porosity. This is in contrast to using conventional autoclave processing, which affords films with weaker mechanical properties (e.g., 0.04 strain) having an inner microstructure with cracks and a rougher surface. In addition, the biodegradability of the polymer film produced using the upsized VFD (6 days) was not compromised relative to that produced using conventional autoclave processing. The overall facile scalable processing in generating a polymer with stronger mechanical properties is devoid of auxiliary substances and is high in green chemistry metrics.