Sound Absorption Analysis of Foamed Rubber Composites from Kenaf and Calcium Carbonate

Sound absorption is any means of reducing the sound pressure by converting it energy into heat within a material. The types of sound absorbing materials determine the frequency distribution of noise to be absorbed. Rubber composites as sound insulators were prepared by incorporation of two types of fillers, namely kenaf and calcium carbonate in blends of 50 mole % epoxidised natural rubber (ENR 50) and methyl methacrylate (MMA)-grafted natural rubber latex. A two-microphone impedance tube was used to investigate the sound absorption coefficient value of the composites prepared. Rubber composites exhibited excellent sound absorption properties with sound absorption coefficient values up to 0.87. The presence of kenaf in the composite was found to create void sections during the drying process, hence increasing the absorption coefficient value of the composite. The presence of calcium carbonate that was scattered on the walls of voids had increased stiffness of the composite, providing better absorption of sound waves.