Acoustical properties of plywood/waste tire rubber composite panels

This paper presents the acoustical performance of plywood/waste tire rubber (PWTR) composite panels. Beech (Fagus orientalis) and alder (Alnus glutinosa) veneers having 1.8 mm thickness were used in the preparation of panels. The wood layers were bonded using commercial urea-formaldehyde (UF) resin, and methylene diphenyl diisocyanate (MDI) was used to form the rubber layers and bond them to the wood veneers. The four variable parameters considered were WTR contents (430 and 720 g), resin contents (120 and 160 g/m2), hot pressing (one- and two-stage), and arrangements of veneer layers. Free vibration based on a free-free bar method was used to evaluate the specific modulus of elasticity, damping factor, acoustic coefficient, and acoustic converting efficiency of the experimental panels. The test results indicated that the sound insulation property of PWTR was highly dependent on the variable parameters. We found that the damping factor and acoustical coefficient of PWTR are significantly affected by the amount of WTR and UF resin content used in the composite. An increase in the usage of WTR and the dosage of UF adhesive considerably improved the soundproof property of the PWTR. An increase in the WTR content in plywood improved the composite's damping factor. Finally, the results demonstrated that the PWTR composite has potential as an interior building material to absorb sound but requires full-scale testing on site. This approach offers an environmental friendly solution to the ongoing problem of WTR.