Yii M.-W.,Malaysian Nuclear Agency |
Wan-Mahmood Z.U.,Malaysian Nuclear Agency
Journal of Radioanalytical and Nuclear Chemistry | Year: 2013
Surface sediment samples were collected at the West (east coast and west coast of Peninsular Malaysia) and East (Sabah and Sarawak) Malaysia in several expeditions within August 2003 until June 2008 for determining the level of natural radium isotopes. Activity concentrations of 226Ra and 228Ra in surface marine sediment at 176 sampling stations were measured. The activity concentrations of both radionuclides in Malaysia (East and West Malaysia) display varied with the range from 9 to 158 Bq/kg dry wt. and 13 to 104 Bq/kg dry wt., respectively. Meanwhile, the ratio distributions of 228Ra/226Ra were ranged from 0.62 to 3.75. This indicated that the ratios were slightly high at west coast of Peninsular Malaysia compared to other regions (east coast of Peninsular Malaysia, Sabah and Sarawak). The variation of activity concentrations of 226Ra and 228Ra and its ratios were also supported by the statistical analyses of one-way ANOVA and t test at 95 % confidence level, whereby there were proved that the measured values were different between the regions. These different were strictly related to their half-life, potential input sources (included their parents, 238U and 232Th), parent's characteristic, the geological setting/formation of the study area, environment origin and behavior. © 2012 Akadémiai Kiadó, Budapest, Hungary.
Halib N.,Malaysian Nuclear Agency |
Amin M.C.I.M.,National University of Malaysia |
Ahmad I.,National University of Malaysia
Journal of Applied Polymer Science | Year: 2010
The formation and swelling behavior of bacterial cellulose/acrylic acid hydrogel prepared from aqueous mixture consists of 20 : 80 (v/v) acrylic acid (AAc) and 1% bacterial cellulose dispersion under accelerated electron beam was investigated. Gel fraction of hydrogel increased with the increasing dose suggesting a denser composite at 50 kGy compared to 35 kGy. SEM photomicrographs revealed a homogenous pores distribution at higher dose with pore sizes ranging from 1 to 5 lm. Hydrogel synthesized at lower dose of electron beam exhibited higher swelling ability and the degree of swelling increased as the pH of surrounding medium increased and it reached the optimum swelling at pH 7. While swelling of the hydrogel decreased with the increasing ionic strength of solution, swelling at different temperatures ranging from 25 to 50°C revealed a unique character where the hydrogel shrunk at 37°C. Moreover, hydrogel synthesized at higher dose exhibited a higher degree of swelling in methanol with respect to water. © 2010 Wiley Periodicals, Inc.
Azhar M.,Malaysian Nuclear Agency |
Ahsanulkhaliqin A.W.,Malaysian Nuclear Agency
AIP Conference Proceedings | Year: 2014
Gamma irradiation is one of the most common procedures in plant mutagenesis and agrobiotechnology activities. The procedures consist of chronic and acute gamma radiation. Generally, 60Co and 137Cs are gamma radiation sources for radiation processing with relatively high energy (half-life 5.27 years for 60Co and 30.1 years for 137Cs). The energy associated with gamma radiation is high enough to break the molecular bonds and ionize atoms without affecting structure of the atomic nucleus (avoiding induction of radioactivity). The Gamma Green House (GGH) is the only chronic irradiation facility in Malaysia, located at Malaysian Nuclear Agency (Nuclear Malaysia). GGH is used for induction of mutation in plants and other biological samples at low dose radiation over period of time depending on the nature and sensitivity of the plant species. The GGH consist of circular green house with 30 meters radius, control room and irradiator with interlock system. The irradiator produces low dose gamma radiation derived from Caesium-137 radioactive source. The biological samples can be exposed to low dose radiation in days, weeks, months or years. The current irradiation rate for GGH is 2.67 Gy/hr at 1 meter from the source. Chronic gamma irradiation produces a wider mutation spectrum and useful for minimizing radiation damages towards obtaining new improved traits for research and commercial values. The prospect of the gamma greenhouse is its uses in research, educations and services on induced mutation techniques for the improvement of plant varieties and microbes. In generating awareness and attract users to the facility, Nuclear Malaysia provides wide range of irradiation services for plant species and mutagenesis consultancies to academicians, students scientists, and plant breeders, from local universities, other research institutes, and growers. Charges for irradiation and consultancy services are at nominal rates. The utilization activities of the gamma greenhouse mainly cover Research and Development, Research Collaboration, Exchange of Information, Irradiation Services, Training Programs, Education, Exchange of Scientists and Seminars/ Conferences. © 2014 AIP Publishing LLC.
Rabir M.H.,Malaysian Nuclear Agency
Nuclear Engineering and Design | Year: 2013
This paper presents the experimental results of the power and temperature coefficients of reactivity of the RTP TRIGA reactor at the Malaysian Nuclear Agency. The power coefficient of reactivity obtained was approximately -0.26 ¢ kW-1 (-1.81 × 10-5 kW-1), and the measured temperature reactivity coefficient of the reactor was -0.82 ¢ C-1 (-5.77 × 10-5 C-1) and -1.15 ¢ C-1 (-8.08 × 10-5 C-1) in IFE C12 and IFE F16, respectively. The power defect, which is the change in reactivity taking place between zero power and the power of 850 kW was ∼2.19 $. Because of the negative temperature coefficient, a significant amount of reactivity is needed to compensate for the temperature change and allows the reactor to operate at the higher power levels in steady state. Throughout this experiment, it is the temperature of the fuel that was measured, not the isothermal temperature coefficient (ITC), which comprises both moderator and fuel. © 2013 Elsevier B.V.
Mohd Amin M.C.I.,National University of Malaysia |
Ahmad N.,National University of Malaysia |
Halib N.,Malaysian Nuclear Agency |
Ahmad I.,National University of Malaysia
Carbohydrate Polymers | Year: 2012
To assist in identifying the utility of novel materials in drug-delivery applications, this study investigated the use of bacterial cellulose (BC), a natural biopolymer, in the synthesis of hydrogels for drug-delivery systems. BC was combined with different proportions of acrylic acid (AA) to fabricate hydrogels by exposure to accelerated electron-beam irradiation at different doses. Fourier transform infrared analysis revealed that the AA had been successfully grafted onto the cellulose fibers and allowed for prediction of the reaction mechanism in the synthesis of hydrogels. Thermal and morphological characterization indicated the formation of thermally stable hydrogels with pore size determined by AA content and irradiation dose. The results of swelling and in vitro drug-release studies revealed the hydrogels to be both thermo- and pH-responsive. Such thermo- and pH-responsiveness, in addition to their morphological characteristics, suggests that these BC/AA hydrogels are promising candidates as controlled drug-delivery systems. © 2011 Elsevier Ltd. All rights reserved.
Ramarad S.,University of Nottingham Malaysia Campus |
Khalid M.,University of Nottingham Malaysia Campus |
Ratnam C.T.,Malaysian Nuclear Agency |
Chuah A.L.,University Putra Malaysia |
Rashmi W.,Taylors University
Progress in Materials Science | Year: 2015
This review addresses the progress in waste tire recycling with a particular attention to incorporation of waste tire rubber (WTR) into polymeric matrices. Methods of waste tire downsizing, importance of WTR characterization and current practice of WTR modification has been emphasized. Detailed discussion on influence of WTR size, loading, modification, compatibilization and crosslinking on the rheological, mechanical and thermal properties of rubber, thermoplastic and thermoplastic elastomer blends utilizing WTR has been reported. By far, thermoplastic elastomer blends; though still in its infancy; has shown the most promising properties balance which is capable of commercialization. Rubber/WTR blends also show ease of processing and acceptable properties. Thermoplastic/WTR blends suffers in term of toughness and elongation at break. However, the waste thermoplastic/WTR is a viable solution to address polymeric waste problem. Review also highlights the lack of studies concentrating on dynamic mechanical, aging, thermal and swelling properties of WTR polymeric blends. © 2015 Elsevier Ltd All rights reserved.
Yacob N.,Malaysian Nuclear Agency |
Hashim K.,Malaysian Nuclear Agency
AIP Conference Proceedings | Year: 2014
Hydrogels are hydrophilic polymer networks that are capable of imbibing large amounts of water. In this work, hydrogels prepared from natural and synthetic polymers were irradiated by using electron beam irradiation. The morphology of hydrogel inter-polymeric network (IPN) was investigated using Scanning Electron Microscopy (SEM). The studies reveal correlations between pore sizes of IPN with degree of cross-linking. This relation also has an effect on swelling properties of the hydrogel. The results indicated that hydrogel with smaller pore size, as a result of much dense IPN, would decrease water uptake capacity. Combination of natural and synthetic polymers to form hydrogel affects the pore size and swelling property of the hydrogel as compared to each component of polymer. © 2014 AIP Publishing LLC.
Atiqah A.,International Islamic University Malaysia |
Maleque M.A.,International Islamic University Malaysia |
Jawaid M.,University Putra Malaysia |
Iqbal M.,Malaysian Nuclear Agency
Composites Part B: Engineering | Year: 2014
The main aim of this paper is to develop kenaf-glass (KG) fibres reinforced unsaturated polyester hybrid composite on a source of green composite using sheet moulding compound process. Unsaturated polyester resin (UPE) and KG fibres in mat form were used at a ratio of 70:30 (by volume) with treated and untreated kenaf fibre. The kenaf fibre was treated with 6% sodium hydroxide (NaOH) diluted solution for 3 h using mercerization method. The hybrid composites were tested for flexural, tensile and Izod impact strength using ASTM D790-03, ASTM D618 and ASTM D256-04 standards respectively. The highest flexural, tensile and impact strength were obtained from treated kenaf with 15/15 v/v KG fibres reinforced UPE hybrid composite in this investigation. Scanning electron microscopy fractography showed fibre cracking, debonding and fibre pulled-out as the main fracture mode of composites and kenaf treated 15/15 v/v KG reinforced hybrid composite exhibited better interfacial bonding between the matrix and reinforcement compared to other combinations. © 2013 Elsevier Ltd. All rights reserved.
Mahmoud Nasef M.,University of Technology Malaysia |
Saidi H.,University of Technology Malaysia |
Mohd Dahlan K.Z.,Malaysian Nuclear Agency
Radiation Physics and Chemistry | Year: 2011
Graft copolymerization of sodium styrene sulfonate (SSS) onto electron beam (EB) irradiated poly(vinylidene fluoride) (PVDF) films was investigated to find out a simple preparation process for sulfonic acid proton exchange membranes with respect to monomer concentration, absorbed dose, temperature, film thickness and storage time. The reaction order of the monomer concentration and absorbed dose of grafting was found to be 2.84 and 1.20, respectively. The overall activation energy for graft copolymerization reaction was calculated to be 11.36 kJ/mol. The initial rate of grafting was found to decrease with an increase in the film thickness. The trapped radicals in the irradiated PVDF films remained effective in initiating the reaction without considerable loss in grafting level up to 180 days, when stored under -60. °C. The presence and distribution of polystyrene sulfonate grafts in the obtained membranes were observed by Fourier transform infrared (FTIR) spectroscopic analysis, scanning optical microscope and scanning transmission electron microscopy (STEM) coupled with X-ray energy dispersive (EDX), respectively. © 2010 Elsevier Ltd.
Sabet M.,University Technology of MARA |
Hassan A.,University of Technology Malaysia |
Ratnam C.T.,Malaysian Nuclear Agency
Polymer Degradation and Stability | Year: 2012
The mechanical test showed that upon irradiation, the tensile strength (TS) values of the EVA/LDPE blends increased with the addition of EVA. A gradual increase in gel content (GC) and tensile strength (TS) with a concomitant decline in elongation at break (EB) and hot set (HS) were observed upon electron beam irradiation of the blends. The densities of all compounds were found to reduce with irradiation. The melt flow index test (MFI) results revealed that addition of ATH and MH reduced the flowability and addition of EVA improved the processability of the LDPE/EVA blend compounds. The TS of the LDPE/EVA blends deteriorated with the addition of flame retardants. The thermal stability and flame behavior of the halogen free flame retarded composites were studied by thermogravimetric analysis (TGA), limiting oxygen index (LOI), and cone calorimeter. The TGA results revealed that the decomposition temperatures of water evolved from the compounds incorporated with MH were significantly higher than that of ATH (i.e. 218-560 °C versus 310-610 °C). The minimum smoke density generation during the combustion obtained with 30% EVA content at both ATH and MH blends. The electrical test showed that the volume resistivity (VR) of the EVA/LDPE blends decreased with increase of EVA, ATH and MH contents, whereas, it declined with increasing irradiation dose. Consequently, this study demonstrated that addition of MH to the irradiated EVA/LDPE blends resulted higher thermal stability, better flammable retardancy, electrical and mechanical properties than addition ATH to the irradiated blends for wire and cable applications. © 2012 Elsevier Ltd. All rights reserved.