Strategies for Enhancing Expansion in Starch-Based Microcellular Foams Produced by Supercritical Fluid Extrusion

Supercritical fluid extrusion is a recent technological development for production of expanded starch-based foams where formation of a microcellular structure is achieved by injection of supercritical CO2 into the melt. The increased effective diffusivity of CO2 in the porous matrix favors get away of the gas to the environment, reducing the amount designed for diffusion into the bubbles, thus posing a significant challenge. This research utilized two approaches to address this issue: increasing the nucleation price and thus the final bubble density in the foam, and lowering the melt temperature. The former was attained by decreasing the nozzle diameter in order to achieve an increased pressure drop rate as the starch-CO2 melt flows through the nozzle. The next methodology was evaluated by presenting a cooling zone prior to the access of the melt into the nozzle. Bubble density improved more than fourfold once the nozzle radius was decreased from 3.00 to at least one 1.50 mm. If you have any questions relating to where and the best ways to utilize plastic compounding machines, you can contact us at our internet site. An increased bubble density resulted in a greater resistance or barrier to diffusion of CO2 to the environment, and increased expansion ratio by as much as 160%. Cooling of the melt led to a reduction in diffusion coefficient of CO2 in the starch melt, and therefore reduced CO2 damage to the environment. The growth ratio increased by 34% because the melt temperature decreased from 60 to 40°C. The above-mentioned strategies can be useful in enhancing and managing expansion, which ultimately determines the textural features of the expanded meals product.