Papers by Author: Abdul Hakim Abdullah

Abstract: Natural fibres are considered as a potential replacement for man-made fibers in composite materials because of their advantages over other established materials. However, serious problem of natural fibres is their strong polar character which creates incompatibility with most polymer matrices. In present investigation, the effect of alkaline, silane and combination of both treatments is investigated. Tensile properties and fracture toughness of coconut spathe fibre for untreated and treated were evaluated. Samples were fabricated by using the hand layup process. Result indicated that silane treatment has achieved a better performance for the tensile test while there is none improvement fracture toughness was displayed by silane or alkaline treatment as compared to untreated fibres. The alkaline treatment showed to be harmful for fracture toughness of the coconut spathe fibre since the improved interfacial adhesion impaired the main energy absorption mechanisms. Keyword: Composites, Coconut Spathe Fibre, Alkaline and Silance Treatment

Abstract: In present investigations, dynamic mechanical thermal behaviours of Arenga Pinnata fibres prior and after alkaline treatment were studied. The alkaline treatments were applied on the Arenga Pinnata fibres by immersed in the alkaline solution, 6% Sodium Hydroxide (NaOH). Using hand lay-out technique, composites were fabricated at 20% and 40% by Arenga Pinnata fibres weight contents. The thermal behaviours of both untreated and treated composites were determined by employing Dynamic Mechanical Analysis (DMTA). The results shows that the treated fibres owned better results of Storage Modulus (E’), Loss Modulus (E”) and Tan Delta temperatures ranges from 0°C to 80°C

Abstract: In this study, fatigue properties of unidirectional Arenga Pinnata fibre reinforced epoxy composites have been investigated under tension-tension fatigue loading. Composites were made at 25% by Arenga Pinnata fibre weight contents using hand lay-out technique. Tensile test was performed prior fatigue loading evaluation. The composites where then were cycled between 90%, 80%, 70% measured from ultimate tensile stress (UTS), with 10 Hz of frequency and stress ratio of R at 0.1. Tensile results indicated that the composites resist to deformation and this reaction denotes that the composites are a brittle material. Fatigue life of composite was improving as the cycled stress decreases. The fatigue resistance were calculated by employing analytical expression and compared with relevant fatigue data.

Abstract: This study presents the assessment of the quality of speech intelligibility of two Malaysian mosques and the results are used to develop a set of general acoustical guidelines to be used in the design of a mosque. Two mosques were selected for the research: Masjid UPM and the Masjid Jamek. The objective of the research is to enable the comparison of the acoustics and speech intelligibility between the mosques as function of the size, volume, occupancy and other parameters of the main prayer hall on the acoustic and speech intelligibility of the respective mosques. The reverberation time (RT60), speech level (SL), background noise (BN), signal-to-noise ratio (S/N ratio) were determined and are used to develop the speech transmission index (STI) and rapid transmission index (RASTI) prediction models for both mosques. It was observed from the results that the RT60, STI and RASTI values shows better performance over number of occupancy for both mosques. Furthermore, the BN and SL results were visualized using the spatial distribution patterns (SDP) of the main hall. The results of the analysis show that the overall acoustic and speech quality of Masjid Jamek is better when compared to the overall acoustic and speech quality of Masjid UPM. These results are then used to develop a set of design recommendations to ensure adequate speech intelligibility quality a mosque.

Abstract: This paper presents the effect of moisture absorption towards thermal modulus evaluation of Arenga Pinnata fibre reinforced epoxy composite. The specimens are produced by hand lay-up method for practically with the ratio of combination of fibre with epoxy and hardener. The fibres were treated with sodium hydroxide (NaOH) prior the composites fabrication. Then, it were submerged in the water for moisture absorption and left for 8 days, 16 days and 30 days. The flexural modulus indicates there is reduction of elastic modulus values over the submerged period. Thermal analysis depicted by storage modulus curve showed the submerged specimens were not affected too much as compared to the control specimens. In fact, their performances were remaining the same across the temperature across from-10°C to 100°C. It is suggested from the experimental result that Arenga Pinnata fibres have a potential prospect as fibre reinforcement composites in many application.

Abstract: Research on natural fibre is keeps on going due to their high strength and stiffness, natural availability, and environmental friendliness. In addition, they are also recyclable, renewable and low in raw material cost. This study was done to determine the performance of aging Arenga Pinnata fibre-reinforced epoxy composite (APFREC) on varying temperature. The specimens were aged from 0 to 90 days by using accelerated aging process and were subjected to dynamic mechanical analysis (DMA) and flexural modulus evaluation. The results have shown that specimens with lower aging days have higher storage modulus initially, that is at below 70 °C but as the temperature increase, its storage modulus drastically decrease in comparison to a more aged specimen. Result of storage modulus at low temperature is similar flexure modulus evaluation. The research indicates that aging APFREC specimens has better thermal resistance.

Abstract: This article presents the storage modulus analysis of kenaf fibre composites that reinforced by two different epoxy matrix systems, named epoxy A and epoxy B. These epoxies are commercially available in Malaysia and been used as a polymer matrix in composite research. Composites were made from hand lay out technique and undergo storage modulus evaluation by using dynamic mechanical analysis (DMA). Fibre content ratios were found to affect the storage capacity in both reinforced epoxy system. However, the addition of 45% kenaf fibre volume ratios reinforced into Epoxy A composites exhibits only week improvement as compared to its rival. The possibility of causes might be attributed to the week interfacial between fibre and matrix.

Abstract: This paper deals with performances and emissions of Jatropha-Palm blended biodiesel as fuel for 4-stroke single vertical cylinder diesel engine. Five fuel samples were tested; i) Diesel fuel supplied by Petronas (PDF); ii) 5% of blended Jatropha-Palm biodiesel and 95% Diesel fuel (B5JPB); iii) 10% of blended Jatropha-Palm biodiesel and 90% Diesel fuel (B10JPB); iv) 15% of blended Jatropha-Palm biodiesel and 85% Diesel fuel (B15JPB); and v) 20% of blended Jatropha-Palm biodiesel and 80% Diesel fuel (B20JPB). Engine performances (specific fuel consumption, brake thermal efficiency) and emissions (exhaust gas temperature and Nox emission) were analyzed and have been discussed in this study. All tests were carried out at varied load conditions which were 0.13, 0.15, 0.17, 0.19 and 0.21 kW. The results revealed that B10JPB blended showed better engine performances compared to its other blends and comparable performances compared to PDF. Comparable Nox emitted of all Jatropha-Palm fuel blended biodiesel fuel sample has been demonstrated to those PDF.

Abstract: The studies emphasis on the development of niobium alloyed ductile iron with higher strength comparing to unalloyed ductile iron. 0.5wt% to 2wt% niobium were added into mixture of ductile iron casting containing pig iron, carburizer and steel scrap, and nodulized through 1.6wt% Fe-Si-Mg addition in CO2 sand casting process. Samples were then machined according to TS EN 10001 standards for tensile test and ASTM E23 for Charpy impact test. In addition, Rockwell hardness test was also performed. Microstructure observations were made after 2% Nital chemical etched and the phase structures were validated through XRD analysis. It was found that addition of niobium in ductile iron provide significant enhancement in mechanical properties when compared to unalloyed ductile iron. Addition of higher amount of niobium had further increased the strength and impact toughness properties. The enhancement of the mechanical properties is expected to further expand the applications of ductile iron.

Abstract: Towards green material, fatigue life of unidirectional kenaf fibre reinforced epoxy composites was investigated made from the hand-layout technique. The composites were subjected to tension-tension fatigue loading at stress ratio of 0.5 and 5 Hz of frequency. Fibre content ratios were found to affect fatigue life on the low cycle fatigue regime strongly as illustrated with stress level versus cycles to failure. It is found that kenaf fibre reinforced epoxy composites with higher fibre content posses higher load carrying capacity and degradation rates.