Mechanical and Acoustical Properties of Short Oil Palm Frond Fibre Reinforced Polyester Composites

This paper presents the determination of tensile, flexural, and acoustical properties of short oil palm frond (OPF) fibre reinforced polyester composites and issues that have to be controlled in order to improve those properties. Three composite samples were fabricated using fibre content of 5%, 10% and 15% (by mass fraction) each. The tensile strength and elastic modulus of the composites were determined by tensile test conforming to the ASTM D638 standard and the flexural strength was measured by the three-point bending test method in accordance to ASTM D790 standard whereas the acoustical properties were determined by transfer function method conforming to the ISO 10534-2 standard. It is showed that the OPF-polyester composites possess greater tensile strength and flexural strength at lower fibre content while the elastic modulus registered increment with higher fibre loadings. Reduction in tensile and flexural strengths at higher fibre content is caused by poor stress transfer mechanism as the combined effect of inadequate fibre/matrix interface adhesion and stress concentration spots. Fibre agglomeration, which causes hindrance to the polyester macromolecule chain mobility, is accounted for the increment in stiffness properties as the amount of fibre is increased. From the measurement of the acoustical properties shows that the sound absorption coefficient is a function of incidence frequency. The normal incidence sound absorption coefficients for different frequencies tend to increase with increasing frequency operation. There is an excellent agreement between the absorption coefficient and the input frequency.