Acoustic performance of natural fibres of oil palm frond ( 30%) and acasia magium ( 70%) with thickness of 18mm

• Main Author: Muhammad Firdaus Bin Che Rahimi
• Published: 2023
• Subjects: Sound absorbing panel

Human healthcare is one of the important aspect that need to be pondered upon developing a new technology and invention in this globalisation era. However, a growth development that has occurred in the urban area especially, is believed to be one of the factor that affect the human healthcare since it increase the noise exposure to the living environment. To curb this issue, developing the sound absorption panel that is made from natural fibres would be the solution to this problem. Hence, this thesis would discuss on the acoustic performance of the sound absorbing panel made by combining two natural fibres, which are Oil palm frond (30%) and Acacia mangium (70%) at four different targeted densities (110 kg/m3, 120 kg/m3, 130 kg/m3, and 140 kg/m3) with constant thickness of 18 mm. The sound panel was fabricated through certain processes that starts with chipping and ends with cooling down process. The fabrication process involves Phenol Formadihalt (PF) glue that acts as a binder to the natural fibres and was mixed by using mechanical blending machine. Once mixed, it was formed in a 30 cm × 30 cm mold before being pressed by a hotpressed machine at 195 oC for 8 minutes. The fabrication process is an important phase in determining the acoustic performance of the sound absorbing panel. The acoustic performance was analyzed based on the Sound Absorption Coefficient (SAC) that was measured at frequency ranging from 0 Hz until 6400 Hz by using Impedance Tube method. This analysis was then supported by Scanning Electron Microscope (SEM) photographs which intended to obtain the morphology of the sound panel structure. SEM photographs were generated by using JEOL Scanning Electron Microscope JSM-6010PLUS/LV. From the analysis, it was found that all samples manage to exhibit minimum SAC value of 0.8 at frequency above 2000 Hz. This shows that the sound absorbing panel has a good acoustic performance and can be the best alternative to the synthetic fibre. Moreover, sound panel with density of 110 kg/m3 and 120 kg/m3 has achieved a unity SAC value of 1.0 at mid-range frequency which are 3512 Hz and 2512 Hz respectively. This indicates that the combination of natural fibres between Oil palm frond (30%) and Acacia mangium (70%) can be a good prospect as sound absorbing material as it can fully absorbed the sound waves that propagate through it. For the morphological analysis based on SEM photographs, it shows that the presence of pores is the reason for the combined natural fibres to exhibit good sound absorption. This relates with factor of porosity. When the presence of pores in a natural fibres with less content of natural fibres itself per unit area of the material, the more the material can absorb the sound waves that coming through it. Hence, this explain on why the sample with lower density can exhibit better sound absorption when compared to the sample with higher density.