UV laser aided micro-cell opening of EPP foam for improvement of sound absorption

This paper deals with the ultraviolet laser aided micro-cell opening (UV LAMO) method for the improvement of sound-absorption of the expended polypropylene (EPP) bead foam. Although the EPP bead foam, which has been used recently as a sound-absorbing material, has light weight, structural strength and durability, its sound-absorbing performance needs to be improved. In this study, we tried to find the optimum conditions for multiplex absorption of sound wave by forming micro channel in the EPP bead foam with a UV laser beam. An EPP bead foam processed by steam-chest molding was used in the experiment. After a UV laser beam was irradiated on the face of the foam, the cell type formed was analyzed by scanning electron microscopy (SEM). The experiment was carried out to verify the effectiveness of the UV LAMO method by analyzing the sound-absorbing characteristics and the types of micro channels of the EPP beam foam to the changes of the expansion ratio of the EPP bead foam.