| Abstract |
Due to the increasing demand for eco-friendly, inexpensive sound absorbers, this study investigated composites made from recycled paper pulp and urea-formaldehyde adhesive. By varying the pulp contents, five samples from used copy paper and five samples from used corrugated board were fabricated. For the same type of porous absorber, one with a lower bulk density has a higher total porosity, resulting in a higher sound absorption coefficient (SAC) spectrum. Sound-absorbing performance of copy paper composites with bulk densities below 442.4 kg/m3 and corrugated board composites with densities of less than 474.8 kg/m3 can be alternatives to commercial polyurethane foam of the same thickness. The noise reduction coefficient (NRC), as well as the average SAC of all corrugated board composites at medium (αM) and high (αH) frequencies were greater than those of copy paper composites. However, the average SAC at low frequency (αL) was not explicitly different for copy paper and corrugated board composites. In conclusion, corrugated board composites are a better candidate as sound absorbers than copy paper composites with the same pulp content. |