Effect of Vermiculite and Bulk Density in the PU Foam Composite Board for the Absorption Coefficient and Acoustic Impedance

Abstract

This article presents a comprehensive investigation in the acoustic characteristics of flame-retardant PET mesh composite fabric and PU foam with the various bulk density of foam and weight ratio of vermiculite. By using impedance tube, absorption coefficients and acoustic impedance of composite material which play an important roles in the estimation of the wave propagation passing through the specific material will be obtained. Results showed that foam with higher bulk density not only increased the material characteristics in the absorption but more importantly, cause the wider band for absorption. With the inclusion of vermiculites, the level of absorption of composite material will obviously increase, especially for the higher frequencies. Instead of 20wt% for vermiculites, the highest absorption coefficient can be found under the 15wt%. On the other hand, acoustic impedance of composite material presented in this article will slowly decrease with frequencies, and the influences of these two parameters are focused on the lower frequency range.