Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral - Monograf
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- PublicationConverting porous β-tcp scaffold containing dicalcium phosphate dihydrate into low crystallinity porous β-tcp scaffold via combination of dry heating and hydrothermal methods(2024-08-01)Lim Beng LitThe study aims to elucidate the feasibility of fabricating low crystallinity porous β-TCP scaffold made from porous β-TCP scaffold containing DCPD using a combination of dry heating and hydrothermal methods. To understand this phenomena, two objectives were established in this study. The first objective is to investigate the effect of setting duration on the properties of porous β-TCP scaffolds containing DCPD using three different setting durations. Several characterisation techniques, including X-Ray Diffraction Spectroscopy (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR) were used to identify the phases present in the scaffolds. The β-TCP scaffolds containing DCPD is successfully set at 14 hours and 20 hours setting duration. Additionally, porosity analysis and compression testing were conducted to understand the mechanical properties of the fabricated scaffolds. The XRD results have validated the presence of DCPD in β-TCP scaffold increases as the setting duration is prolonged. While maintaining the β-TCP phase, the SEM also revealed the interlocking mechanism of DCPD between the β-TCP granules. The second objective is to investigate the effect of CaCl2 concentration on the conversion of porous β-TCP scaffolds containing DCPD into low-crystallinity porous β-TCP scaffolds under hydrothermal conditions at 200°C. The SEM results show that the needle-like crystal has been precipitated showing the DCPD phases have partially converted into DCPA. The results demonstrate that by employing a combination of dry heating and hydrothermal methods, the porous β-TCP scaffolds containing DCPD set by using 14 hours setting duration and hydrothermal treated in 0.5 mol/L CaCl2 has the most conversion to low-crystallinity porous β-TCP scaffolds.
- PublicationEffects of spent coffee grounds in pectin polysaccharide thin film on resistive switching characteristics(2024-08-01)Leong Hao ZheAlthough inorganic-based Resistive Random Access Memory (ReRAM) has shown promising performance to fulfil the current requirement of high-speed dense memories, it can lead to generation of e-waste which harms the environment. Hence, bio-organic-based ReRAM is developed as a sustainable alternative. The purpose of this research is to improve the resistive switching (RS) performance of pectin ReRAM device through comparing the effect of different spent coffee grounds (SCGs) concentration incorporated into the thin film and the effect of different thin film drying temperature, on the RS performance of the device. Therefore, different concentration of SCGs (0 wt%, 1 wt%, 3 wt%, 5 wt%, and 7 wt%) was incorporated into 5.5 mg/ml pectin precursor solution by microwave-assisted solvent exchange technique. Then, the prepared precursor solutions were spin-coated onto ITO-coated PET substrates and dried at different temperatures (120 oC, 140 oC, 160 oC and 180 oC) for 2 hours before sputtered with gold top electrode. Several characterization techniques were used such as PSA, FTIR, EDX, TGA, goniometer, zeta potential analysis, AFM and SPA to evaluate the effect of SCGs in pectin thin film on RS behaviour. The results showed that pectin ReRAM device with 5 wt% SCGs incorporated and dried at 140 oC has the best RS performance, providing an ON/OFF ratio of 3.53 x 104, which is 101.71% higher compared with pristine pectin ReRAM device. In conclusion, this study demonstrates the potential of SCGs as a promising additive to enhance the RS performance of bio-organic-based ReRAM.
- PublicationDevelopment of piezo-assisted zinc oxide-based photocatalysts grown by direct heating method(2024-08-01)Lai Yue ChengIndustrial development and population growth have increased waste generation, stressing water resources. ZnO is widely used in photodegradation for wastewater treatment due to its unique properties. However, ZnO possess limitations in efficiently utilizing visible light and exhibits inefficiencies in the absence of light. It exhibits rapid recombination of charge carrier, hindering their sustained and effective use. This affects the overall photocatalysis performance of ZnO. This project utilized the DH method to investigate the effect of synthesis duration on ZnO rods grown on kanthal meshes. Following this, an Au layer was sputtered onto the pre-grown ZnO nanorods and the piezo-assisted ZnO-based photocatalyst was examined for MB removal under different light sources and stirring conditions. The synthesized samples were characterized by XRD, FESEM, XPS, Raman, RTPL and UV-visible spectroscopy. The average length and diameter of the optimized ZnO rods were 1.847 μm and 0.292 μm, respectively. The average photocurrent measured by Au/ZnO was 1.977 mA under UV light, 1.6 mA under visible light, and 1.201 mA in dark conditions with stirring. These findings were correlated with the removal of MB dye, i.e. under UV light, visible light, and in dark conditions with stirring. The higher photocatalytic performance of Au/ZnO in visible light was attributed to the LSPR of the Au which facilitated efficient charge carrier transport and suppressing recombination of electrons and holes. In conclusion, Au/ZnO/kanthal mesh composites demonstrated positive performance to degrade MB dye under illumination of UV light, visible light, and in dark conditions, especially in the presence of stirring.
- PublicationBiodegradable polyvinyl alcohol (pva) /carboxymethyl cellulose (cmc) halochromic film using natural dye from red cabbage(2024-08-01)Khor Wan HuiThe conventional pH indicator film is often synthetic and non-biodegradable, which can contribute to pollution and environmental degradation. In this research, a biodegradable halochromic film was fabricated using natural dye (anthocyanin) from red cabbage, PVA, and CMC and formed into film through the solution casting method. Solid-liquid extraction method was used to extract anthocyanin from red cabbage, and the optimum parameters, such as type of solvent, temperature, and time to extract a higher amount of anthocyanin, were determined. Responsiveness of halochromic film with different amounts of PVA/CMC (100/0, 80/20, 60/40, 40/60, 20/80, 0/100) was determined by using air exposure from different pH buffer solutions (pH 2–pH 12) by observing the colour change within 120 seconds and analysing the total colour difference (ΔE) by using colour analysis software. Characterization of the film was done through FTIR, swelling test, tensile test and reusability test. The finding shows the optimum parameters to extract higher amounts of anthocyanin were a 1:1 ratio of ethanol to distilled water, 70°C of heating, and an extracted duration of 30 minutes. The halochromic film with higher CMC content undergoes a faster and more obvious colour change when air exposure to different pH buffer solutions. The tensile strength and Young’s modulus increase, while elongation at break decreases as CMC content increases. Anthocyanin halochromic film shows a good sensor at pH 2, 11, and 12 as it changes to red at pH 2, green at pH 11 and greenish yellow at pH 12. Halochromic film made from 60% PVA and 40% CMC shows a balance in both colour response time and mechanical properties.
- PublicationStudy of calcium salt coating on mechanical and bioactivity properties of bg45s5/cordierite(2024-08-01)Khoo Xhu HearnThe BG/cordierite composite has an improved mechanical properties over pure BG45S5, though its bioactivity which is a critical feature for medical applications is reduced. This study explores the fabrication and evaluation of a Bioactive Glass 45S5 (BG45S5) and cordierite composite coated with hydroxyapatite (HA) for potential use in bone tissue engineering. The fabrication process involved forming BG45S5 and cordierite powders, combining them into a pellet, and treating them with varying concentrations of calcium salt solutions before immersion in simulated body fluid (SBF). X-ray Diffraction (XRD) indicated the initial amorphous state of BG45S5, which crystallized upon sintering, while cordierite remained crystalline. Bioactivity was confirmed by the presence of carbonate apatite peaks in calcium-treated samples post-SBF immersion. Fourier Transform Infrared Spectroscopy (FTIR) identified functional groups that supported bioactivity. The composite's mass loss in SBF suggested dissolution behavior and apatite formation, with higher calcium salt concentrations enhancing bioactivity. Density and porosity measurements indicated that more calcium salt led to more porous structures, aiding bone integration. An initial rapid pH increase in SBF due to calcium ions, which stabilized over time, reflected the composite's interaction with the fluid. Diametral Tensile Strength (DTS) tests showed that calcium salt treatment improved mechanical properties, with higher concentrations yielding greater tensile strengths. The BG45S5/cordierite composite demonstrates potential for bone tissue engineering, combining enhanced bioactivity and mechanical integrity.