Production of Cellular Polymers Without Solid Outer Skins by Gas Dissolution Foaming: A Long-Sought Step Towards New Applications

An innovative approach to reduce and eliminate the non-foamed solid skins of the cellular polymers fabricated by gas dissolution foaming is presented in this work. The incorporation of a flexible gas diffusion barrier on the polymer surfaces during the saturation and foaming processes provided significant reduction or even hindered the appearance of the non-foamed solid skins while enabling appropriate expansions in several polymers (PMMA, PS, PC, and PCL). Besides, this approach has allowed to achieve significant expansions by foaming polymer samples with thicknesses in the order of magnitude of the non-foamed solid skins, i.e., thin films (<100 µm). This paper discusses how the gas diffusion barrier allows reducing the solid skins, the mechanisms involved in the gas diffusion process, and the possibility of interconnecting the inner cellular structure with the external medium.