Bee Ying Lim

Rheological and Thermal Study of Chitosan Filled Thermoplastic Elastomer Composites

The chitosan filled thermoplastic elastomer (TPE) composites with different filler loading was prepared by melt mixing at 180 °C. The effect of 3-aminopropyltriethoxysilane (3-APE) as coupling agent on the rheological and thermal properties of composites were investigated. The melt flow indexer was used to characterize the melt flow index (MFI) of TPE/Chitosan composites at temperature of 180 to 210 °C. It was found that addition of chitosan into composites had reduced the MFI values. Besides that, the MFI values of composites were found to increase linearly with temperature. The treated composites demonstrated lower MFI values, indicated that better interfacial bonding was established between chitosan and TPE and the flowability of the composite melts was hindered. The TGA results reported that the treated composites had better thermal stability and lower total weight loss as compared to untreated composites at similar filler loading.

Synthesis of Nanoporous Zinc Oxide by Anodizing of Zinc in Distilled Water

In this work, ZnO nanoporous thin films were formed by anodizing of Zn plates in 500 ml distilled water of 25°C at voltage ranged from 10 V to 30 V. As anodized zinc plates were characterized by using SEM and XRD. Characterization of as anodized Zn plates using SEM showed that the morphology of the as anodized Zn plates were significantly influenced by the anodizing voltages. Nanoporous ZnO thin films were formed when 25 V and 30 V were used while ZnO thin films without nanoporous structures were formed when 10 V, 15 V and 20 V were used. XRD analysis indicated the ZnO thin films formed at 10 V to 30 V were of hexagonal wurtzite structures.

Synthesis of Silicon Carbide Nanowhiskers from Graphite and Silica of Different Ratio by Microwave Irradiation Assisted Synthesis

In this paper, the effect of ratio of silicon dioxide and graphite for the synthesis of silicon carbide nanowhiskers by microwaves heating was reported. The mixtures of SiO2 and graphite with different ratio were prepared by ultrasonic mixing using ethanol as medium. The mixtures were dried on hotplate and cold pressed by using hydraulic hand press uniaxially into a pellet die. The mixture in the form of pellet were heated up to 1400 °C at heating rate of 20 °C/min and soaked for 30 minutes. Scanning electron microscopy was used to study the morphology of sample of each different ratio of mixture. It was found that almost complete conversion of graphite and silica to silicon carbide nanowhiskers was observed for sample of mixture SiO2 and graphite in the ratio of 1:3. Result from x-ray diffraction analysis also indicated that single β-SiC phase was present in the diffractogram of silicon carbide nanowhiskers synthesized from mixture SiO2 and graphite in the ratio of 1:3.

Green Synthesis of Silicon Carbide Nanowhiskers by Microwave Heating of Blends of Palm Kernel Shell and Silica

Silicon carbide nanomaterials especially silicon carbide nanowhiskers (SiCNWs) has been known for its excellent properties such as high thermal stability, good chemical inertness and excellent electronic properties. In this paper, a green synthesis of SiCNWs by microwave heating of blends of palm kernel shell (PKS) and silica was presented. The effect of ratio of PKS and silica on the synthesis process was also studied and reported. Blends of PKS and silica in different ratio were mixed homogenously in ultrasonic bath for 2 hours using ethanol as liquid medium. The blends were then dried on hotplate to remove the ethanol and compressed into pellets form.. Synthesis was conducted in 2.45 GHz multimode cavity at 1400 °C for 40 minutes. X-ray diffraction revealed that β-SiC was detected for samples synthesized from blends with ratio of PKS to silica of 5:1 and 7:1. FESEM images also show that SiCNWs with the average diameter of 70 nm were successfully formed from blends with ratio of PKS to silica of 5:1 and 7:1. A vapour-liquid-solid (VLS) mechanism was proposed to explain the growth of SiCNWs from blends of PKS and silica.

Synthesis of zinc oxide thin film by anodizing

In this work, 99% purity zinc plates were anodized at potentiostatic conditions in distilled water at 25°C. The anodizing voltages were varied from 10 V to 30 V. The morphologies of the ZnO thin film were investigated by using scanning electron microscope (SEM) and the compositions were confirmed through the characterization using X-ray diffraction (XRD). The current versus time transients during the anodizing were recorded. SEM images show that thread-like nanostructures were present on the surface of Zn plates anodized at 25 V and 30 V. XRD patterns revealed that ZnO were present on all Zn plates anodized at anodizing voltages ranged from 10 V to 30 V. Current recorded during the anodizing process increased with the anodizing voltages due to the formation of thread-like nanostructures with lower electrical resistance.

Fabrication of Cu2O Nanostructured Thin Film by Anodizing

Abstract Cuprous oxide, a narrow bandgap p-type semiconductor, has been known as a potential material for applications in supercapacitors, hydrogen production, sensors, and energy conversion due to its properties such as non-toxicity, easy availability, cost effectiveness, high absorption coefficient in the visible region and large minority carriers diffusion length. In this study, Cu2O nanostructured thin film was fabricated by anodizing of Cu plates in ethylene glycol containing 0.15 M KOH, 0.1 M NH4F and 3 wt.% deionized water. The effects of anodizing voltage and temperature of electrolyte were investigated and reported. It was found that nanoporous Cu2O thin film was formed when anodizing voltages of 50 V and 70 V were used while a dense Cu2O thin film was formed due to the aggregation of smaller nanoparticles when 30 V anodizing voltage was used. Nanoplatelets thin film was formed when the temperature of electrolyte was reduced to 15 °C and 5 °C. X-ray diffraction confirmed the presence of Cu2O phase in thin film formed during anodizing of Cu plates, regardless of the anodizing voltage and temperature of electrolyte. Photoluminescence spectroscopy showed the presence of Cu2O peak at 630 nm corresponding to band gap of 1.97 eV. A mechanism of the formation of Cu2O thin film was proposed. This study reported the ease of tailoring Cu2O nanostructures of different morphologies using anodizing that may help widen the applications of this material

Synthesis of SiC nanowhiskers from graphite and silica by microwave heating

Abstract Silicon carbide (SiC) is an important ceramics for engineering and industrial applications due to its advantage to withstand in high temperatures. In this article, a demonstration of SiC nanowhiskers synthesis by using microwave heating has been shown. The mixtures of raw materials in the form of pellets were heated, using a laboratory microwave furnace, to 1400 °C for 40 minutes at a heating rate of 20 °C/min. The characterization process proved that the mixture of graphite and silica in the ratio of 1:3 is an ideal composition for synthesizing single phase β-SiC nanowhiskers. Vapor-solid mechanism was suggested to explain the formation of SiC nanowhiskers by the proposed microwave heating.

Characterization of Silicon Carbide Nanowhiskers Synthesized by Microwave Heating Using Photoluminescence Spectroscopy and Fourier Transform Infrared Spectroscopy

Silicon carbide is an attractive material for engineering and industrial applications in harsh conditions. In manufacturing process, conventional heating process is commonly used to synthesis the silicon carbide. In this study, SiC nanowhiskers were synthesized from microwave heating of mixture of graphite and silica in the ratio of 3: 1. The mixture was heated by using laboratory microwaves oven to 1400°C at heating rate of 20 °C/min and temperature was hold for 30 minutes. Photoluminescence spectroscopy and Fourier transform infrared spectroscopy were used to characterize the SiC nanowhiskers. Photoluminescence spectrum of SiC nanowhiskers showed a sharp peak at 420 nm corresponding to band gap of SiC (2.39 ev). FTIR absorption spectra of SiCNWs recorded a band at 805.22 cm-1 corresponding to Si-C bond.

Palm Kernel Shell Filled Recycled High-Density Polyethylene: Effect of Filler Loading

Palm kernel shells (PKS) filled recycled high density polyethylene (rHDPE) biocomposites were produced using melt mixing. The biocomposites were prepared on Brabender Plasticorder at temperature of 185 °C and rotor speed of 50 rpm by varying filler loading (0 to 40 phr). In this study, the effect of PKS loading on rheological properties and thermal stability of rHDPE/PKS were investigated. Rheological study of the biocomposites was carried out by means of capillary rheometer under temperature of 190 °C, 200 °C and 210 °C. Thermal properties of biocomposites were studied by using thermo gravimetric analysis (TGA). The rheological results showed that the flowability of the composite increased with increasing temperature. Meanwhile, the result of TGA showed that at higher PKS loading, rHDPE/PKS biocomposites had lower total weight loss. The thermal stability of the biocomposites was reduced due to the addition of filler loading.

Synthesis of Porous Anodic Alumina (PAA) on Aluminum Alloy AA6061 in Mixture of Phosphoric Acid and Oxalic Acid

In this study, porous anodic alumina was formed on aluminum alloy AA6061 by anodizing using mixture of 0.3 M oxalic acid and phosphoric acid with concentration ranged from 0.1 M to 1.0 M. AA6061 alloys were anodized at 40 V and 25°C for 60 minutes. FESEM images show that the uniformity of the pores arrangement of porous anodic alumina decreased with the increasing concentration of phosphoric acid in the electrolyte. Well-ordered porous anodic alumina was formed in mixture of 0.3 M oxalic acid and 0.1 M phosphoric acid while disordered porous anodic alumina were formed when the concentration of phosphoric acid were in the range of 0.3 M to 1.0 M. Pore size and interpore distance were found to increase with the concentration of phosphoric acid in the mixture. X-ray diffraction patterns show that to γ-Al2O3 were formed on the surface of AA6061 after the anodizing process, regardless of the concentration of phosphoric acid in the mixture electrolyte.