Controlled Phase Separation in Flexible Polyurethane Foams with Diethanolamine Cross-Linker for Improved Sound Absorption Efficiency

For comfortable driving conditions, flexible polyurethane (PU) foams are used for sound absorbers in noise, vibration, harshness (NVH) systems. The cellular structures of PU foams are important to improve the sound absorption efficiency, and the cell morphology is strongly dependent the use of experimental ingredients such as catalysts and cross-linking agents. Uniform cavity size distribution is achieved by controlling the catalyst ratio between gelling and blowing catalysts, and the optimum catalyst ratio (9:1) is used with a diethanolamine (DEA) cross-linker for improved sound absorption efficiency. DEA affects pore morphology by preventing phase separation in PU matrix, and the number of open pores reduces with increasing DEA contents. Sound absorption coefficient shows the highest at 9:1 catalyst ratio and 0.9 g DEA usage in the flexible PU foams under disturbed phase separation conditions.