Polyurethane composite foams including CaCO₃ fillers for enhanced sound absorption and compression properties

Polyurethane (PU) foams are versatile in automotive applications for sound absorption and seat cushioning products due to their easiness of manufacturing process and cost effectiveness. In this study, PU composite foams including CaCO₃ fillers after chemical treatments with oleic acid were fabricated to examine the sound absorption and compressive properties. The cell and pore sizes in the PU composite foams did not show much differences with filler contents, but the open porosity revealed clear difference depending on the chemical treatments. The open porosity had lower values with chemically treated fillers than with no-treated cases, and it resulted in the high sound absorption coefficient. The compression strengths were also higher with the chemically treated fillers than with no-treated filler cases. Stress relaxation and hysteresis loss showed superior results with the chemically treated fillers compared with the cases with no-treated cases, and it is mainly due to the enhanced interfacial contacts and compatibility between PU matrix and CaCO₃ filler surfaces. Therefore, it is much important to modify the filler surface characteristics for good interfacial compatibility to achieve improved physical properties of the PU composite foams.