Sound absorption characteristics of natural fiber filled in flexible foam upon UV irradiation exposure

Wood filler- flexible foam composite (FC) has been studied and proved to have ability to absorb sound. In this study, untreated and treated Meranti Merah wood dust and Palm Trunk namely as MM and PT respectively was use as the filler. Therefore, this study was developed to compare the behavior and the ability of FC towards sound absorption coefficient based on conditions of the fillers and wood fiber sizes. With the size of <355 and <500 μm, three different percentages has been selected which is 10 wt%, 15 wt% and 20 wt% for both type of woods. Subsequently, these samples have been tested by using Impedance Tube test for determination of sound absorption coefficient (SAC). The morphological structure has been test using Scanning Electron Microscopy (SEM) to observe the pores structure of wood-FC. While, Fourier Transform Infrared (FTIR) was used to determine the functional group of FC and UV-Weatherometer was used to determine the resistance of FC towards UV light up to 1000 hours. As a result, the SAC shows value at achievable frequency range of 2500 to 6000 Hz. The highest SAC is 0.995 while the lowest SAC is 0.600. Nevertheless, a result of FC after UV exposures shows only small decreases in SAC values and frequency absorption for some samples were slightly shifted toward higher range for example sample 15 wt.% untreated <355 μm Meranti-FC curve shift from 4500 to 5000 Hz after 1000 hrs UV exposures. The pores structures after UV light exposures shows slightly increasing in sizes and the SAC values decreased for all samples. As a conclusion, in this study, the SAC behavior of <355μm Meranti Merah, <500μm Meranti Merah, <355μm Palm Trunk and