The effects of density on microstructure and acoustic properties of opt natural fibers

Abstract

Palm oil is the world's most productive oilseed trim. Malaysia is one the largest producers and exporters of palm oil in the world. Almost 4.49 million hectares of land in Malaysia are under oil palm cultivation and producing 17.73 million tons of palm oil and 2.13 tons of palm kernel oil in a year. Therefore, oil palm wastes have created a major disposal problem in Malaysia. Producing materials from oil palm trunk (OPT) natural fibers can minimize and recycle the waste to our environment. This paper reports the effects of density on microstructure and acoustic properties of OPT natural fibers as sound absorbing material in four different targeted densities (120 kg/m³, 140 kg/m³, 160 kg/m³ and 180 kg/m³, 140 kg/m³, 160 kg/m³) show a minimum SAC of 0.8 over a wide frequency range of 3000 - 6400 Hz. The maximum SAC (α) = 0.91 can be reached by a sample with a density of 120 kg/m³. However, sample with a density of 180 kg/m³ does not exhibit high absorption rate due to compact fiber within the sample. Morphological analysis was conducted using Scanning Electron Microscope (SEM). The structure of parenchyma and vascular bundle play an important role in determining the acoustic properties.

Keywords: Oil Palm Trunk (OPT), Natural Fiber, Sound Absorption Coefficient (SAC, α), Microstructure