Showing papers by "Abu Bakar published in 2014"

Mechanical and thermal properties improvement of nano calcium carbonate-filled epoxy/glass fiber composite laminates

Abstract: In this work, the influence of precipitated nano calcium carbonate (PNCC) on the mechanical and thermal properties of epoxy/glass fiber (GF) laminates was studied. The mechanical properties of the ...

Transformational leadership and teamwork improvement: the case of construction firms

Abstract: Purpose – A need for effective leadership and adequate managing the personnel is vital for every construction organization. Meanwhile, the dynamic and complex environments of the industry may be caused that not much research has been conducted on leadership practices in the industry. The purpose of this paper is to study the leadership style of the construction leaders in Iran and explore the correlation of transformational leadership practices with teamwork improvement in the construction companies. Design/methodology/approach – The research analysis was completed on a sample population of 107 managers within nominated construction firms in Iran. The analysis methods in this research were mainly descriptive and regression-based analyses and the type of investigation was a co-relational study. Findings – The research found the level of the leaders’ orientation for people and task in their leadership style, their transformational leadership qualities, and the relationship of transformational leadership wit...

Thermal properties and aging characteristics of chemically modified oil palm ash-filled natural rubber composites

Abstract: The chemically modified oil palm ash (OPA) with the cetyltrimethylammonium bromide (CTAB) solution was prepared prior to compounding with the natural rubber and other curing ingredients. The aging resistance and thermal stability of CTAB-modified OPA-filled natural rubber composites were evaluated in the same manner as non-modified OPA samples. The retention tensile properties after thermal aging was measured and based on the result shown, the CTAB-modified OPA-filled natural rubber composites imparted insignificant effect to aging resistance as compared to the non-modified OPA-filled natural rubber composites at very low OPA loading; however, the effect became apparent beyond 3 phr OPA loading where the CTAB-modified OPA-filled natural rubber composites provided better aging resistance than the corresponding non-modified OPA-filled natural rubber composites. The thermogravimetric analysis indicated that the CTAB-modified OPA-filled natural rubber composites exhibited lower thermal stability which showed lower temperature at their respective weight loss and lesser char residue than that of non-modified OPA-filled natural rubber composites. This was attributed to the CTAB which started to decompose at the temperature of 210 °C. However, for the range from ambient temperature to 210 °C, the CTAB-modified OPA-filled natural rubber composites produce better thermal stability than those of non-modified OPA-filled natural rubber composites.

Predicting the Coefficient of Thermal Expansion of Pultruded Composites with a Natural-Fiber Reinforcement

Abstract: Thermal expansion problems for unidirectional pultruded composite samples were studied. The composite materials were subjected to temperatures ranging from 0 to 200°C in order to simulate service conditions. A thermal-mechanical analyzer was employed for gathering experimental data, and the results were compared with those generated using the ANSYS software and micromechanical models. A finite-element analysis (FEA) by utilizing ANSYS was also carried out. The thermal behavior of pultruded jute-fiber-reinforced unsaturated polyester composites was simulated, and the results obtained were then compared with experimental data and predictions provided by several micromechanical models. It is found that the Schapery and Chamis micromechanical models are more efficient in predicting the value of CTE in the longitudinal and transverse directions, respectively.

PHYTOCHEMICALS, ANTIOXIDANT AND ANTIPROLIFERATIVE PROPERTIES OF FIVE MOSS SPECIES FROM SABAH, MALAYSIA Original Article

Abstract: Objective: This study was conducted to investigate the phytochemical contents, the antioxidant and antiproliferative properties of 80% methanol, ethanol and aqueous extracts of Sphagnum cuspidatum subsp. subrecurvum, Sphagnum cuspidatulum, Sphagnum junghuhniannum, Pogonatum cirratum subsp. fuscatum and Pogonatum cirratum subsp. macrophyllum. Methods: The total phenolic and total flavonoid contents were analysed using Folin-Ciocalteu and aluminium chloride colorimetric methods. The antioxidant properties were evaluated by three different assays, namely, ferric reducing/antioxidant power (FRAP), ABTS and DPPH free radical scavenging assays. MTT assay was used to study the antiproliferative properties against selected cancer cell lines. Results: The results showed that the aqueous and ethanol extracts of S. cuspidatum subsp. Subrecurvum has the highest total phenolic and total flavonoid content with the values of 5.42 ± 1.95 mg gallic acid equivalent per g of dry sample and 2.12 ± 0.02 mg catechin equivalent per g of dry sample, respectively. The 80% methanol extracts of S. junghuhnianum has the lowest total phenolic and total flavonoid content with the values of 0.80 ± 0.12 mg gallic acid equivalent per g of dry sample and 0.03 ± 0.02 mg catechin equivalent per g of dry sample, respectively. None of the extracts displayed IC 50 value (concentration that inhibits 50% of free radical) at concentration tested. The 80% methanol extracts of P. cirratum subsp. Fuscatum induced antiproliferative activity against CaOV 3 Conclusion: Results obtained indicated that the selected mosses contained considerable amount of phenolics and flavonoids which contribute to antioxidant properties. P. cirratum subsp. Fuscastum and S. cuspidatulum have the potential to be used in pharmaceutical industry due to the ability of these two species to induce antiproliferative activity against CaOV (ovarian carcinoma) cell line whereas S. cuspidatulum induced antiproliferative activity against HepG2 (liver cancer) cell line. None of the extracts induce antiproliferative activity against MDA-MB-231 (non-hormone dependent breast cancer) cell line.

A Review on Recycling Ash Derived from Elaeis guineensis By-product

Abstract: Oil palm (Elaeis guineensis) ash is defined as the waste generated after the combustion of oil palm biomass. Malaysia is one of the world’s largest producers and exporter of palm oil in the world, and there is approximately 4 million tonnes of oil palm ash generated annually. It is estimated that the amount of oil palm ash will keep increasing due to the high demand for palm oil globally. Normally, oil palm ash is disposed without any beneficial economic return value. The awareness of this environmental crisis has increased significantly over the past few years. With the evolution of ash utilization strategies, interest in oil palm ash in various research fields has grown. Through the effort of researchers and information available, the properties of the resulting materials are affected by the percentage of substitution and particle size of the oil palm ash. The major challenges in utilizing oil palm ash are discussed in this paper, as are the beneficial effects, which can include reducing the negative environmental impact and the product cost. Although the recycling of oil palm ash is still a new focus of interest, the main thrust of waste management in Malaysia will continue to focus on this kind of research and will attempt to solve the problem of disposal of the ash as well.

Assessing Knowledge Management Processes and Competitive Advantage in Local Authorities using Knowledge Management Assessment Instrument (KMAI)

Abstract: For academics and professionals, knowledge management has been widely known as a core agenda and has been recognized as one of the most important sources of competitive advantage. Managing knowledge to achieve organizational performance is not only crucial for private sector institutions, but it is significant for the public sector institutions as well. Since the study of knowledge management in the public sector is still in its infancy, this study is aimed at investigating the relationship between knowledge management processes and competitive advantages in local authorities in Malaysia to raise the awareness of the importance of managing organizational knowledge, particularly in the public sector. For this study, the data was collected from selected Heads of Departments in 42 institutions of local authorities in Peninsular Malaysia and yielded 82 usable responses. The analysis suggests that all six knowledge management processes (knowledge creation, capture, organization, storage, dissemination, and application) have a strong relationship with competitive advantage. This study is expected to raise awareness and provide initial guidelines to local authorities as knowledge-intensive institutions to formulate strategies on how to manage the knowledge management processes within the organization. Abu Hassan Abu Bakar Universiti Sains Malaysia, Malaysia Wiwied Virgiyanti Universiti Sains Malaysia, Malaysia Muhammad Asim Tufail Universiti Sains Malaysia, Malaysia Mohamad Nizam Yusof Universiti Sains Malaysia, Malaysia

Chemically modified oil palm ash‐filled natural rubber composites and its properties

Abstract: Chemically modified Oil Palm Ash (OPA)-filled natural rubber composites were prepared by modifying the functional group of OPA with cetyltrimethylammonium bromide (CTAB) prior to compounding by using laboratory conventional laboratory-sized two-roll mills. The functional groups of CTAB-modified OPA were analyzed by using Fourier Transform Infrared (FTIR) and compared with those of non-modified ones. The CTAB-modified OPA-filled NR composites showed shorter scorch time and cure time as compared to those of non-modified OPA, which was attributed to the new functional groups occurred. The tensile test results showed that the OPA-filled NR composites with CTAB modification exhibit improvement in tensile strength, tensile modulus, and hardness but lower elongation at break as compared to nonmodified ones. The tensile fractured surface of modified OPA filled NR composites revealed the well embedded and better distribution of CTAB-modified OPA in NR matrix. The toluene uptake was also found to be lower for the modified OPA-filled NR composites and showed better rubber–filler interaction; it further showed that surface modification with CTAB could compatibilize the OPA particles and NR matrix. POLYM. COMPOS., 35:691–697, 2014. © 2013 Society of Plastics Engineers

Mechanical, thermal and water absorption behavior of hollow epoxy particle–filled polyester composites

Abstract: A water-based emulsion method was used in this study to produce hollow epoxy particles. The hollow epoxy particles were then chemically treated with hydrochloric acid solution to eliminate the excessive calcium carbonate on the surface of the hollow epoxy particles. The hydrochloric acid–treated hollow epoxy particles were added to the polyester matrix at different loading values (0–9 wt%). The addition of 5 wt% hollow epoxy particles to the polyester matrix optimized the mechanical properties (i.e., tensile strength, tensile modulus and flexural strength) of hollow epoxy particle–filled polyester composites. The interlocking of the polyester matrix into the pore regions of the hollow epoxy particles strengthened the polyester composites. The addition of hollow epoxy particles to the polyester matrix increased the thermal stability, storage modulus and the glass transition temperature of the polyester composite. The water absorption and diffusion coefficient of the polyester composite were also increased ...

Characterization and Properties of Pretreatment Effect on Oil Palm Ash Filled Natural Rubber Vulcanizates

Abstract: This article describes the study of the feasibility of pretreatment effect on oil palm ash (OPA) with hydrochloric acid (HCl) before compounding with the natural rubber (NR) using a conventional two roll mill. Results revealed that metal elements such as calcium and magnesium had been reduced from the OPA particle after treated by HCl solution, meanwhile the surface tended to be rougher and provided bigger pores on the surface. Scorch and cure times for HCl-treated OPA were longer with higher tensile strength, tensile modulus and hardness as compared to the nontreated OPA-filled NR vulcanizates.

Effects of transformational leadership behavior on the relationship between team condition and team performance

Abstract: Since teams shape the primary focus of construction project lifecycle, a high-performance construction workplace facilitates employees' technical and innovation skills through team development. From theoretical perspective, this study extends team condition assessment as a hierarchical reflective construct. The research analysis was completed using a sample population of 94 construction teams from three different sources: team members rated their leader's transformational leadership behavior, team leaders evaluated team conditions, and lastly, supervisor of each team leader rated team performance. The model shows that team condition as a second-order reflective construct has significant direct and indirect impacts on team performance. In addition, the results indicate that the transformational leadership behavior of team leaders plays a mediating role between team condition and team performance.