Current and Past Issues

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Effect of cationic charging agent on the bonding strength of coarse Titanium particles deposited by electrophoretic deposition


Pages 1-15

Lau Kok Tee* and Charles Christopher Sorrell

PDF (759 K)

Abstract

Electrophoretic deposition (EPD) is a potential coating technique for surface hardening of steel when combined with a subsequent rapid sintering process. This process requires synergy between suspension particles and charging agent, particularly when the particles involved are noncolloidal in nature. The present work will investigate the effect of three commercially-available cationic charging agents; aluminium (III) chloride (AlCl3), polyethyleneimine (PEI) and poly (diallyldimethylammonium chloride) (PDADMAC) on the EPD of coarse Ti particles onto steel. Surface microstructure, deposit yield, electrophoretic mobility and electrical conductivity were used to characterize Ti particles and obtained Ti deposit. The key finding of the present study is the bonding strength of charging agent-adsorbed coarse Ti particles deposits predominantly controlled their deposit yield. Electrophoretic mobility of the Ti particles only played a lesser role in the deposit yield because of strong hindrance of gravity on the moving coarse particles. Charging agent, which gave the strongest to the weakest bonding strength is as follow: AlCl3, PDADMAC (Mw = 100,000 -200,000 amu), PDADMAC (Mw = 400,000 -500,000 amu), PEI.

Keywords: Titanium Particles, Electrophoretic Deposition, Bonding Strength, Coating, Polyelectrolyte

Effect of gamma radiation on the tensile properties of epoxidized natural rubber latex


Pages 17-25

Chai Chee Keong*, ChantaraThevy Ratnam, Luqman Chuah Abdullah, Mohamed Syafiq Shaik Mohamed Amin, Wan Manshol Wan Zin

PDF (335 K)

Abstract

Gamma irradiation on epoxidized natural rubber latex, of 25 and 50 mole% poxidation levels (ENRL-25 and ENRL-50), was carried out with particular attention to the effect of gamma radiation on tensile properties of ENRL. ENRL was irradiated as received with gamma radiation doses ranging from 20 to 160 kGy. Cast films were prepared from irradiated ENRL which were used for determination of tensile properties and gel fraction. Significant increment of modulus and tensile strength, and gradual reduction of elongation at break of ENRL films were observed. ENRL-25 and ENRL-50 showed optimum radiation dose at 80kGy and 60kGy respectively. The gel fraction was found to increase with irradiation. ENRL-25 showed higher tensile properties and gel fraction values than ENRL-50. Such observation was attributed to the presence of more unreacted double bonds in ENRL-25 which participated in the irradiation-induced crosslinking.

Keywords: Epoxidized natural rubber latex, Irradiation, Irradiation-induced crosslinking

Thermal properties and morphologies for polymer blends comprising of epoxidized natural rubber and semicrystalline thermoplastic


Pages 27-37

Chin Han Chan*, Siti Farehah Sulaiman, Hans-Werner. Kammer, Lai Har Sim, Mohomad Kamal Harun

PDF (745 K)

Abstract

Thermal properties and morphologies of epoxidized natural rubber (ENR)-based blends are discussed. Poly(ethylene terephthalate) (PET), poly(3-hydroxybutyrate-co-3- hydroxyvalerate) (PHBV) and poly(ethylene oxide) (PEO) were blended with ENR as the second component. The two glass transition temperatures that correspond to the neat constituents in the ENR blends reflect immiscibility of the ENR with the second component. Rate of crystallization of PET and PEO remains constant when mass fraction of ENR (WENR) ≤ 0.4, whereas the rate of crystallization becomes slower when WENR ≥ 0.5. The entrapment of the ENR amorphous region either intra or/and interspherulitically at higher content of ENR for the PET or PEO in the blends has caused the reduction in the rate of crystallization for the crystallizable component. For PHBV and its blends, fine intraspherulitic dispersion of ENR in PHBV can be observed when the WENR ≥ 0.2. Decreasing of the rate of isothermal crystallization of PHBV is detected with increasing ENR content.

Keywords: Epoxidized natural rubber, Poly(ethylene terephthalate), Poly(3-hydroxybutyrateco-3-hydroxyvalerate), Poly(ethylene oxide)

Effect of cationic charging agent on the bonding strength of coarse Titanium particles deposited by electrophoretic deposition


Pages 39-49

Jin-Luen Phua*, Pei-Leng Teh, SupriAbdul Ghani, Cheow-Keat Yeoh

PDF (423 K)

Abstract

A blend system consist of two types of thermoset polymer, epoxy and unsaturated polyester at ratio of 80/20 weight percentage (wt. %) filled with 0, 20 and 40 volume percentage (vol. %) of recycled copper powder as conductive filler was prepared and undergone thermal aging process for 40 days. The changes on volumetric dimension of the blend composites were studied. The aged blend composites were undergone characterization and testing which include flexural, hardness, volumetric shrinkage and electrical conductivity properties. After thermal aging, the flexural strength of the blend composites increased started from 20 vol.%of filler loading. Besides that, the hardness properties and electrical conductivity were also improved after thermal aging.

Keywords: Polymer blend, Recycled copper, Thermal aging, Epoxy, Unsaturated polyester

Effect of Hydrophilic Nanoclay on Morphology, Thermal and Mechanical Properties of Polylactic Acid / Polycaprolactone / Oil Palm Mesocarp Fiber Biocomposites


Pages 51-70

Chern Chiet Eng, Nor Azowa Ibrahim*, NorhazlineZainuddin,Hidayah Ariffin, Wan Md. Zin Wan Yunus, Yoon Yee Then

PDF (745 K)

Abstract

The effect of addition of hydrophilic nanoclay on polylactic Acid (PLA)/polycaprolactone (PCL)/oil palm mesocarp fiber (OPMF) biocomposites were investigated. The composites were prepared by melt blending technique and the composites were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogvavimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). FT-IR spectra indicate that there is no major peak shifting or formation of new peak in the composites spectra. Intercalated types of PLA/PCL/clay nanocomposites were confirmed by XRD and TEM results. Based on mechanical properties results, PLA/PCL/OPMF/clay bionanocomposites shows better tensile strength and elongation at break than PLA/PCL/OPMF biocomposites. TGA results show that the presence of clay increases the thermal stability of the bionanocomposites. SEM micrographs revealed that PLA/PCL/OPMF biocomposites consists of cavity indicated poor fiber/matrix adhesion while micrographs of PLA/PCL/OPMF/clay bionanocomposites show better fiber/matrix adhesion as no cavity present at facture surfaces .

Keywords: Bionanocomposites, Biodegradable Polymers, Clay, Natural Fiber

Layer-by-layer deposition of CoFe2O4 nanocrystals onto unbleached pulp fibres for producing magnetic paper


Pages 73-89

Chin Hua Chia*, Sarani Zakaria, Seng Chau Goh, Chi Hoongchan

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Abstract

Magnetic fibres were prepared by layer-by-layer (LBL) deposition of cobalt ferrite (CoFe2O4) nanocrystals onto unbleached kenaf pulp fibres. Polyacrylamide (PAM) was used to change the negative charge of the pulp fibre to positive so that the negatively charged CoFe2O4 nanocrystals could be readily deposited onto the surface of the fibres. The deposition of CoFe2O4 nanocrystals onto fibre increased linearly to 115 mg/g of fibre deposited with 40 wt% CoFe2O4 nanocrystals solution and started to fluctuate after the addition of 40 wt% which could probably be due to no more available sites on the fibre for further deposition of the CoFe2O4 nanocrystals. Magnetic paper was formed using layer-bylayer deposition on fibres by adding 40 wt% CoFe2O4 nanocrystals for each layer. The degree of magnetic loading and magnetic properties could be adjusted by varying the number of deposition layers. LbL deposition method produced magnetic fibres with better retention than that of in situ synthesis method.

Keywords: Cobalt ferrite; magnetic fibres; magnetic nanoparticles; polyacrylamide

The Performance of SnAgCuPt Solder on Bi-Facial Solar Cell under the Sun


Pages 91-105

Chin Hua Chia*, Sarani Zakaria, Seng Chau Goh, Chi Hoongchan

PDF (836 K)

Abstract

The performance of a solar panel is expected to be improved by using a low resistivity solder in the interconnection of bi-facial solar cells. Two solar panels were constructed using the popular Sn-3.8Ag-0.7Cu solder and a new Sn-3.8Ag-0.7Cu-0.2Pt composite solder as interconnection material. The power outputs of both solar panels under the sun were measured constantly throughout one week using an IV plotter and the total energy yields were calculated and compared. The total energy yield increases by 9.68% for the solar panel with the new Sn-Ag-Cu-Pt composite solder compared to that with the conventional Sn-Ag-Cu solder. This provides an alternative approach to boost the solar panel performance. Both solar panels have almost the same maximum power output throughout the week showing that the new solder is stable and shows no sign of degradation under the sun.

Keywords: Bi-facial solar cell, Composite solder, Interconnection, Power output

Effect of aluminium and indium doping on structural and optical properties of ZnO nanoparticles prepared by mechanochemical processing


Pages 107-123

Nurul Syahidah Sabri, Ahmad Kamal Yahya, Nur Aimi Jani, Mohamad Kamal Harun, Mahesh Kumar Talari*

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Abstract

This paper reports the effect of Aluminium and Indium doping on structural and optical properties of ZnO (Zn1-xAlxO and Zn1-xInxO: x = 0, 0.02, 0.04, 0.06, 0.08) nanoparticles prepared by mechanochemical processing in a high-energy ball mill and heattreated at 500°C and 600°C. The emission results revealed the stronger blue emission compared to UV and green emissions which is contradictory to the most previous reports, where other methods were employed for ZnO synthesis. The higher blue emission intensity was due to higher interstitial defect concentration in ZnO nanoparticles, which were produced by the mechanochemical processing. The red shift in Eg with increasing ‘Al’ and ‘In’ doping was possibly due to band tailing effect. The reduction in UV intensity of emission spectra with increased ‘In’ doping may be due to Coulomb screening effect. In contrast, increment in UV intensity of emission spectra with ‘Al’ doping was attributed to radiative recombination processes.

Keywords: ZnO nanoparticles, ‘Al’ doped ZnO, ‘In’ doped ZnO, Mechanochemical processing, Optical properties

Plasticizer as a salt dissociator: a FT-IR investigation


Pages 125-134

Nurul Syahidah Sabri, Ahmad Kamal Yahya, Nur Aimi Jani, Mohamad Kamal Harun, Mahesh Kumar Talari*

PDF (403 K)

Abstract

Fourier transform infrared (FT-IR) spectroscopic studies have been undertaken to investigate the interactions between plasticizer ethylene carbonate (EC) and propylene carbonate (PC) with lithium trifluromethanesulfonate (LiCF3SO3) salt. Evidences of ECLiCF3SO3 and PC-LiCF3SO3 interactions have been manifested as frequency shifts and alteration in band shapes. Differences in the interactions of EC and PC with LiCF3SO3 are noted. The PC-LiCF3SO3 interaction tends to favor the formation of ion aggregates as compared to EC-LiCF3SO3 interaction.

Keywords: Ethylene Carbonate; Propylene Carbonate; LiCF3SO3; FT-IR.

Non-toxic mineral based instumescent fire retardant coating for structural applications


Pages 137-156

Faiz Ahmad*, Sami Ullah, Wan Farhana Mohammad, Hammad Aziz, Zaiful Ikmal Zohari

PDF (403 K)

Abstract

The results of gaseous products of mineral fillers based intumescent fire retardants coatings are presented. The control coating was developed using ammonium polyphosphate (APP) as acid source, expandable graphite (EG) as carbon source, melamine (MEL) as blowing agent, zinc borate (ZB) as additives, Bisphenol A (BPA) as epoxy resin with tetra ethylene tetra amine (TETA) as the hardener. Inorganic fillers such as aluminum tri hydrate (ATH), alumina and talc were used in the control formulation and resultant coating was coated onto steel substrate. The coated samples were tested for gaseous products released during decomposition and Pyrolysis Gas Chromatography-Mass Spectrometry (GC-MS) was used. The coatins were tested for char expansion and scanning electron microscope was used for microstructural studies.The chemical composition of residual char was analyzed using X-ray Diffraction (XRD). Results showed that the formulation with higher percentage of ATH gave off less concentration of the gaseous products and was considered more environmental friendly. The analysis of gaseous products showed the presence of benzyl alcohol. Char was composed of boron oxide, carbon (graphite) and boron phosphate which were stable at high temperature and helped to reduce the heat flow to the structural.

Keywords: Intumescent coating, Pyrolysis, Gas chromatography, X-ray diffraction