Papers by Author: Izman Sudin

Abstract: Magnesium (Mg) alloys are promising biodegradable implant materials. If successful, they do not require second surgical operation for their removal. However, the focus of this study is to address the limitation of fast degradation rate (DR) which hinders the clinical application of Mg alloys. The bio-corrosion rate of any intermetallic alloy is related to its beta (β) phase volume fraction. Thus, homogenization heat treatment (HHT) was carried out to reduce the β phase. The influence of β phase and the hydroxyapatite powders (HAp) was employed to slow down the initial DR of Mg AZ91 alloy. Samples were cut from Mg grade AZ91 alloy ingot in 10mm x 10mm x 3mm dimension. The samples were prepared and divided into two; the first part was classified as as-received sample (sample a) while the second one was processed for HHT. HHT was carried out at 410°C/10h, cooled inside the furnace and named as homogenized sample (sample b). The HAp was synthesized using a simple wet chemical precipitation technique (SWCPT) and deposited on sample b via electrophoretic deposition (EPD) at different voltages with different deposition times. The HAp, uncoated and coated samples were characterized. Potentiodynamic polarization (PP) and immersion tests were carried out in stimulated body fluid (SBF) to estimate the DR and in vitro bioactivity of Mg AZ91 respectively. The results revealed a significant drop in DR from sample a (1.421 mm per year) to coated sample h (3.73 x 10^-4 mm per year). Keywords: Magnesium alloy, biodegradable implants, beta phase, homogenization heat treatment, hydroxyapatite, electrophoretic deposition.

Abstract: The need to develop surviving implants and bone substitutes with good biocompatibility, mechanical strength and bioactivity, without causing toxicity, immune rejection and cancer had attracted the attention of many researchers over the years. Hydroxyapatite (HA) is one of the excellent calcium phosphates and major mineral component of vertebrate bone and teeth, which considerably enhances the biocompatibility, mechanical strength and bioactivity of artificial biomaterials in the body system. In addition, it creates porous and rough coated surface that aids the cell attachment, proliferation and the growth of tissue on the bone implants. Due to its high demand in biomedical applications, scientists had developed several, simple and efficient techniques to produce HA. This review outlines several techniques of manufacturing HA and summarizes the merits and demerits of each technique. Keywords: Biomaterials, calcium phosphate, hydroxyapatite, preparation techniques and bone

Abstract: In recent decades, polymer composites have gained significant interests within the research community due to its high strength-to-weight ratio. Its properties, such as low cost, lightweight, corrosion resistance, and impact resistance, make it desirable for both household and industrial applications. However, the reliability of the composite model with density influence is still challenging. In this study, experiments were carried out using epoxy systems of varying densities to fabricate oil palm empty fruit bunch (OPEFB) carbon nanoparticle composites to investigate the influence of matrix density on its Weibull modulus. It is found that the increase in matrix density increases the nanocomposite reliability. A Weibull modulus of 9.5, 82.2 and 183.4 were obtained for low, medium and high matrix density nanocomposites, respectively. Such findings would facilitate the development of particle-reinforced composites.

Abstract: Numerous literatures have suggested that the use of natural fiber as filler can improve the mechanical properties of a polymer composite. Oil palm empty fruit bunch fibers (OPEFB) are no exception and have shown to exhibit good mechanical properties, with the potential to produce environmentally friendlier composites. In this study, the tensile strengths and morphologies of micro OPEFB filled composites with varying loadings (0.3125 wt% to 10 wt%) were investigated. It was found that increasing content of OPEFB reduces the translucency of the composite almost linearly. It was also revealed that the addition of 0.3125 wt% to 2.5 wt% has a reinforcing effect, observing improvement up to 17.4% compared to its neat condition. Such findings would facilitate the development of an effective OPEFB reinforced polymeric nanocomposite.

Abstract: During the composite’s fabrication process, one of the most common defect occurs is void. Numerous literatures have suggested that the presence of void negatively affect its mechanical properties and effective degassing process is one the solutions for such issue. In this study, experiments were carried out using neat E132 epoxy to investigate the effects of different degassing process (hot water, ultrasonic bath, and vacuum) on its tensile strength. The duration of its process was carried out from 5 – 9 minutes for hot water and ultrasonic bath where vacuum process was extended until 10 minutes to observed limiting behavior. It is found that the vacuum degassing method is the most effective. Vacuum degassing process displayed the least formation of bubble and micro voids even for 10 minutes. It is also revealed that vacuum degassing process resulted the highest average tensile strength at 48.8MPa. Such findings would facilitate the well bonded effective nanocomposite fabrication process.