Studies on the Sound Absorption Coefficient-temperature-frequency Relationship on Polymer

The sound absorption coefficients of polyethyl methylacrylate (PEMA) and polyvinyl chloride (PVC) were investigated by means of the impedance tube technique. The results showed that the sound absorption coefficient of the materials exhibited a higher value in its glass transition region due to the more sound energy lost by converting it into the heat energy. Moreover, the further studies discovered that PEMA and PVC possess the characteristic sound absorption frequencies. When the PEMA and PVC were in their glass transition region, the number of their characteristic absorption peaks increased. The phenomena can be partly explained from free volume theory. The diagrams on the three-dimensional relationship of sound absorption coefficient-temperature-frequency for PEMA and PVC were obtained which were of important significance in the application of noise reduction.