Investigation of Acoustic Properties of Polymer Nanocomposites regarding Combined Sound Absorption and Insulation Characteristics

Introduction: Nowadays multiple techniques have been developed to noise control. One the most important way is the control based on sound absorption and insulation. The purpose of current study was to improve the acoustic properties of soft polyurethane foam regarding combined sound absorption and insulation characteristics. Materials and Methods: Polyacrylonitrile and polyvinylidine fluoride nanofibers are fabricated using solution electrospinning technique. Nano-clay particles (montmorillonite, 1-2 nm in diameter) were purchased from Sigma-Aldrich, Inc. Experimental design was prepared using Design-Expert ver.7 software. The 50 samples of nanocomposites were fabricated on the basis of experimental run. The measurement of sound transmission loss and the absorption coefficient was conducted using BSWA SW477 550005 Impedance Tubes according to the standard ASTM E2611-09 and ISO10534-2, techniques. Response surface methodology (RSM) with central composite design (CCD) was applied to optimize the conditions to produce nanocomposites for each frequency range. Results: The polymer nanocomposites had the higher combined sound transmission loss and the absorption coefficient than pure polyurethane foam. Their combined transmission loss and the absorption coefficient in the low, middle and high frequency range was 02.02, 1.91 and 2.53 times higher than the pure polymer. The combined transmission loss and the absorption coefficient in all frequency ranges have been increased by increasing the thickness of the composites and air gap. At a thickness of 2 cm, the combined composites, sound transmission loss and the absorption coefficient increased with the increase of content of both nanofibers. The highest combined transmission loss and the absorption coefficient was observed when mass fraction of nanofibers was in at its maximum level. Conclusion: This study showed that the adding nano-clay particles, polyacrylonitrile and polyvinylidine fluoride nanofibers to polyurethane foam can lead to increased sound transmission loss and the absorption coefficient. The obtained optimized nanocomposite can be applied to noise control where requiring the absorption as well as reduction of sound transmission.