Flame retardant sound absorbing panel made from bamboo charcoal and natural kaolin clay

As noise pollution affects mental and physical health, sound absorbing panels are used to reduce noise pollution problems, especially the use of natural materials instead of synthetic materials in the fabrication of sound absorbing panels. Bamboo charcoal and natural kaolin clay were applied for eco-friendly flame retardant sound absorbing panels. The appropriate ratio of natural materials for forming sound absorbing panels to obtain the maximum sound absorption ability was investigated. In addition, the effects of the mixture ratios and thicknesses of sound absorbing panels on sound absorption, mechanical properties, and flame resistance were studied. The noise reduction coefficient (NRC) was determined according to ISO 354:2006 and ASTM C 423. At a thickness of 7 mm, the mixture materials obtained the highest sound absorption coefficient of 0.4 with a weight ratio of bamboo charcoal: natural kaolin: water: latex compound of 97: 3: 200: 50, respectively. It also has properties with a density of 327.62 kg/m3, a water absorption value of 9.14%, and a maximum tensile strength of 453.66 N, according to TIS 535-2527. The microstructural characteristics of the fabricated sound absorbing panel were investigated using scanning electron microscopy, which revealed good adhesion and high porosity. The flammability tests were performed according to ASTM D3801 and ASTM D635 for the vertical and horizontal positions, respectively. The appropriate mixture ratios presented for vertical burning obtained a V-0 classification, and horizontal burning obtained an HB classification. The flame retardant sound absorbing panel made from natural materials, including bamboo charcoal as a sound absorber and natural kaolin clay as a sound absorbing support, can be achieved because when it is ignited, it turns into ashes that can assist in extinguishing the fire by itself and not spread the flame. Bamboo charcoal powder and natural kaolin clay showed good performance for both sound absorption and flame retardancy. These are the natural alternative materials that can be used to develop commercial flame retardant sound absorbing panels.