A convenient and efficient path to bead foam parts: Restricted cell growth and simultaneous inter-bead welding

Abstract

Wide density range and flexible geometry design make bead foam parts capture a large share of the polymeric foams market. However, traditional steam-chest molding process used to prepare bead foams involves complex molding facilities and high energy consumption. Herein, a novel in-mold foaming and molding (IMFM) method using supercritical CO2 as blowing agent was developed for the preparation of bead foam parts. TPU pellets were loaded in a special mold and TPU bead foam parts were fabricated in-mold after pressure quench. The molded parts with a density of 0.2 g/cm3 presented an elongation at break of 217 % and a ball rebound of 58 %. The energy loss coefficients of the bead foams remained lower than 12 % during the 100-time cyclic compression process. Restricted cell growth and simultaneous inter-bead welding in limited space were the key elements for this novel method. This method opens a new route to the production of bead foams with high performance in a convenient and efficient process.