Theses & Dissertations

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Browsing Theses & Dissertations by Department "Universiti Malaysia Perlis"
  • Publication
    A study on physical separation processes for recovery metals from waste printed circuit boards (PCBs)
    ( 2011)
    Aimi Noorliyana Hashim
    In view of increasing the waste PCBs, a physical separation process has been carried out to recover metals from waste PCBs. This research is aimed to implement an effective and environmental friendly recovery particularly cooper (Cu) of waste PCBs. The physical separation process begins with comminution to produce controlled particle size. Then, the separation process was divided into two parts according optimum efficiencies at specific size range. The size fraction -600+300µm and -1180+600µm were separated by gravity separation using Mozley laboratory separator. Afterwards, an enrichment step of concentrate fraction was done by magnetic separation using rare-earth roll magnetic separator. Meanwhile, the size fraction -150µm, -300+150µm, and -600+300µm were separated to froth flotation using Denver D-12 laboratory flotation cell. Characterisations of waste PCBs were performed by micrographic analysis and elemental analysis. A qualitative micrographic analysis was conducted using stereo- zoom microscope, optical microscope, and scanning electron microscopy. An elemental analysis was conducted using atomic absorption spectroscopy (AAS) analysis and energy dispersive spectrometer (EDS). Regarding on the particle size analysis, maximising recovery of physical separation is done by targeting recovery in a controlled four size range fraction; -150µm, -150+300µm, - 300+600µm and -600+1180µm. A qualitative liberation assessment of the waste PCBs particle was establish unliberated particles still remain in the waste PCBs fines (-75µm). As the highest metal element in waste PCBs, copper (Cu) recovery (R) and enrichment ratio (ER) was discussed with more emphasis in this project. By Mozley laboratory separator, Cu recovery increase from 80.85% (ER 2.07) at -600+300µm size fraction to 89.65% (1.93) at -1180+600µm size. Thus, the efficiency of gravity separation increases with increasing particle size. A significant of the low recovery at finer size fraction implies valuable metal loss at this size range, thereby be evidence that it is not very effective for finer particles (- 300µm) was recovered by Mozley laboratory separator. For enrichment step using Rareearth roll magnetic separator showed the enrichment ratio (ER) was highly improved. At - 600+300µm non-magnetic fraction, Cu enrichment ratio is 2.51 and 2.15 at -1180+600µm size fraction. Through the reverse froth flotation, higher Cu recovery (R) and lower Cu enrichment ratio (ER) are noticeably with increasing particle size fraction for both flotation conditions (with and without frother). Thus, the efficiency of froth flotation is higher at finer size fraction. At -75µm size fraction, Cu recovery is 84.66% (ER 3.03) under natural hydrophobic responds (without frother). Meanwhile with frother addition, Cu recovery is 82.16% (ER 3.37). In view of frother addition, there is improved in enrichment ratio but poor recovery percentage. Overall, the approach physical separation has high efficiency, easy to run and at same could recover metals and non-metals. It is expected that physical separation process will be developed for the upgrading of metals recovery in waste PCBs.
      2  6
  • Publication
    Applicability of protease and urea as a molluscicide for Pomacea canaliculata (Siput Gondang Emas)
    ( 2015)
    Noor Hasyierah Mohd Salleh
    Pomacea canaliculata is regarded as one of the most destructive molluscs as it causes severe damage to paddy fields. This mollusc is commonly combated by using chemical molluscicide like metaldehyde, which is known as toxic chemicals, therefore causes negative impact to the farmers and the environment. Hence, there is a great demand for a user and environmental-friendly molluscicide to reduce P. canaliculata population. The present study investigates the applicability of protease and urea as an alternative molluscicide for combating both flesh and eggs of P. canaliculata. Studies on the effect of each agent on snail eggs cover chemical and physical analyses; namely unhatchability, cuticle protein profile, water loss, conductivity, gas exchange and morphological changes. For snail flesh, it covers biological, chemical and physical studies, namely, mortality, respiration, food intake, responsiveness, movement, protein, ammonia and peroxidase level of the flesh. The studies were extended by producing cell free extract protease (CFE protease) using locally available raw material like cassava, and subsequently applied as a biomolluscicide. Likewise, studies regarding urea were also extended by using coated urea with rice husk ash and starch before subsequently applied to the paddy demonstration plot. For the flesh of P. canaliculata studies, it was found that the mortality were 31% and 90% after exposure to 3.9U/mL CFE protease and 0.02M urea respectively for 20hrs. It was also observed that the respiration rate increased proportionally with the increase of urea concentration. Additionally, the exposure to CFE protease and urea also reduced the snail appetite, responsiveness and movement as compared to the control snail. Extension of the work using coated urea for paddy plot studies saved 93% of paddy from snail attack. As for the P. canaliculata eggs studies, 71%, 52% and 35% hatchability have been suppressed after treating to 0.75U/mL commercial protease, 0.19U/mL CFE protease and 0.02M urea respectively. Besides that, the rate of conductivity, water loss and respiration increased proportionally with the increase of either commercial protease activity or urea concentration. The findings from these studies show the applicability of protease and urea as a molluscicide for both the flesh and eggs of P. canaliculata.
      1  8
  • Publication
    Characterisation and properties of aluminium/zinc oxide composites as catalytic gases from depolymerisation of low density polyethylene to liquid oil
    ( 2012)
    Nurul Razliana Abdul Razak
    The effects of addition zinc oxide (ZnO) or magnesium trisilicate (MTS) in aluminum (Al) matrix composites on physical and mechanical properties at different sintering temperature were studied. The Al/ZnO and Al/MTS composites prepared by powder metallurgy (PM) method. The composites were mixed using a milling machine at a speed of 131 rpm with ball to powder weight ratio is 10:1, then compressed at 200 MPa for 2 minutes. The results show that the additions of ZnO or MTS in Al composites have increased the density and hardness but decrease the compressive strength of the composites. The Al/ZnO or Al/MTS composites sintered at 750 °C have higher density, hardness and compressive strength than composites sintered at 650 °C. The effect of different sintering temperature gives effect to intensity of the composites. The microstructure of Al/ZnO or Al/MTS sintered at 750 °C show better interaction between filler and Al matrix. The effect of stearic acid or zinc stearate in Al/ZnO composites has increased the hardness and compressive strength of composites but density reduced at sintered 750 °C. The XRD patterns of Al/ZnO composites with stearic acid or zinc stearate show the changed in intensity peak of composites. The presence of stearic acid and zinc stearate as binder improved the adhesion and interaction between ZnO and Al matrix composites. The Al/ZnO composites with zinc stearate have higher physical and mechanical properties compared to other composites. The applied of Al/ZnO composites with zinc stearate as catalyst in the depolymerisation of low density polyethylene (LDPE) has produced yield 76.22 % of liquid oil. The liquid oil product consists of light hydrocarbons such as gasoline was proven by using gas chromatography - mass spectrometer (GC-MS).
  • Publication
    Characteristics and properties of activated carbon from bamboo filled Styrene Butadiene Rubber (SBR) vulcanizates
    ( 2016)
    Nor Munirah Rohaizad
    Carbonized bamboo and bamboo activated carbon (AC) were prepared via carbonization process and chemical activation process using potassium hydroxide (KOH) as activating agent. Carbonization process was conducted at different carbonization temperature (250, 450 and 650 ºC) with heating rate of 5 and 15 ºC/min. As carbonization temperature increased, the percentage of char yield decreased, however the carbon content increased. The BET surface area of carbonized bamboo increased with increasing carbonization temperature and more pores were created as shown in SEM micrographs. Carbonized bamboo produced at 650 ºC with heating rate 15 ºC/min showed the highest potential to produce bamboo AC, subsequently used as filler in SBR compounds owing to its higher carbon content with higher BET surface area. Next, carbonized bamboo and bamboo activated carbon filled SBR (SBR-CGS and SBR-AC) compounds with varying filler loading from 10 to 50 part per hundred rubber (phr) were prepared. The effects of filler loading on the cure characteristics, physical and tensile properties were determined. Results showed that the improvement in cure characteristics for both SBR-CGS and SBR-AC vulcanizates. The physical properties of both filled SBR vulcanizates improved in terms of increment in hardness and decrement in resilience as the filler loading increased. Besides, the tensile properties for both SBR-CGS and SBRAC vulcanizates also enhanced which the tensile strength and tensile modulus as well as elongation at break (EB) increased. The morphology studies showed that both filler dispersed homogeneously in SBR compounds, resulted in good filler-rubber interaction and consequently improved the tensile properties. Comparing both filled SBR vulcanizates, it showed that SBR-AC vulcanizates have better properties than SBR-CGS vulcanizates due to the porosity of bamboo AC filler. SBR-AC vulcanizate with 50 phr of bamboo AC exhibited optimum properties and was selected to be added with transpolyoctylene (TOR) as compatibilizer. Incorporation of TOR into SBR-AC vulcanizates showed slightly increment in tensile strength and reduction in hardness and tensile modulus as the compatibilizer loading increased from 2 to 8 phr.
  • Publication
    Characterization and properties of palm kernel shell filled low density polyethylene biocomposites
    ( 2011)
    Romisuhani Ahmad
    Biocomposites based on palm kernel shell (PKS) and low density polyethylene (LDPE) was investigated. The biocomposites were prepared by using Z-Blade mixer at processing temperature 180 oC and rotor speed 50 rpm. The effect of filler loading of PKS as filler in LDPE on mechanical properties, water absorption, morphology, thermal properties and fourier tranformation infrared spectroscopy (FTIR) were studied. The results show that the increasing of filler loading have decreased the tensile strength and elongation at break but increased the Young’s modulus and water absorption. The morphology study using scanning electron microscopy (SEM) shows poor interfacial interaction between PKS and LDPE with increasing of the filler loading. The crystallinity of the biocomposites increased with increasing of PKS loading. To improve the mechanical properties, compatibilizer, Polyethylene co-acrylic acid (PEAA) was used. The effect of chemical modification of biocomposites with polyethylene co-acrylic acid (PEAA), acrylic acid (AA) and coconut coupling agent (COCA) enhanced the tensile strength, Young’s modulus and crystallinity of the biocomposites but reduced the elongation at break and water absorption. The morphology study (SEM) shows that the filler-matrix interaction was improved with incorporation of PEAA, AA and COCA. The FTIR results show that the wave number of hydroxyl group for all biocomposites shifted to lower wave number which indicates that interaction between the hydroxyl groups from PKS with compatibilizer and coupling agent.
  • Publication
    Citric acid leaching process for silica extracted from oil palm ash for zeolite synthesis
    ( 2017)
    Faizul Che Pa
    Agricultural wastes such as oil palm ash have a possibility to be utilized as a useful renewable source for production of energy and silica (SiO2). Extensive researches have been carried out to extract silica from agricultural wastes, due to silica as a useful raw material for industrial application. Oil palm ash is one of the waste material from the palm oil industry where is was obtained from the burning process of solid waste such as empty fruit bunch, shell and fiber. Oil palm ash contains a large amount of silica. This study has been conducted to extract silica from palm ash by removing impurities using citric acid via leaching process. Various experimental parameters, such as acid concentration (1 to 6 %), reaction time (30 to 180 minutes), leaching temperature (30 to 90 C) and solid/liquid ratio (1:50 – 1:10) were investigated. Then, the effect of each parameter towards extraction process was evaluated using XRF, FTIR, XRD and SEM. The optimum extracting condition was achieved at 3% concentration of citric acid, 70C of solution temperature, 60 minutes of reaction time and 1:25 ratio of solid/liquid. XRF results show that the content of silica in treated palm ash can reach up to 92% after citric acid leaching treatment. The transmittance peaks at 798 - 778 cm-1 show that silica element is absent in the treated palm ash. Preliminary tests have shown that there is a possibility of using silica extracted from palm ash to synthesize zeolite.
      1  5
  • Publication
    Design, processing and properties of fly ash-based lightweight geopolymer using foaming agent for brick application
    ( 2018)
    Wan Mastura Wan Ibrahim
    Lightweight concrete reduces the overall self-weight of the structures resulting in the reduction of the foundation size, cost, and other specification. However, the conventional lightweight concrete production causes several environmental impacts and produce low mechanical properties, so there is a clear need of searching and replacing for more efficient and durable alternatives beyond the limitations of the conventional lightweight concrete. Geopolymer represents a great opportunity to ensure greater sustainability in the construction industry especially for the use of industrial waste such as fly ash. This research focuses on the preparation of fly ash-based lightweight geopolymer using superplasticizer as foaming agent. The superplasticizer (Polyoxyethylene alkyether sulfate) was prepared using pre-formed method by combination with water and air pressure. The effects of geopolymeric synthesis parameters such as the NaOH concentration (6 M, 8 M, 10 M, 12 M and 14 M), ratio of foaming agent to water (1/10, 1/20, 1/30 and 1/40) by volume, ratio of foam to geopolymer paste (0.5, 1.0, 1.5 and 2.0) by volume, curing temperature (40 °C, 60 °C, 80 °C and 100 °C) and curing time (6, 12, 24 and 48) hours on the lightweight geopolymer paste that affect the mechanical and microstructure properties were studied in detailed. The compressive strength, water absorption, density, were studied to determine the mechanical properties of lightweight geopolymer. The thermal insulation properties was investigated through the effects of thermal conductivity, thermal diffusivity, and specific heat of lightweight geopolymer at different ageing time (3, 7, 28, 60 and 90) days. The microstructure properties of lightweight geopolymer were tested by using Scanning Electron Microscope. The results indicated that the lightweight geopolymer have an optimum NaOH concentration of 12 M, with highest compressive strength of 15.2 MPa at 7 days, an optimum ratio of foaming agent to water (1/10) and ratio of foam to geopolymer paste (1.0) with highest strength of 16.6 MPa (7 days), optimum curing temperature (80 °C) and curing time (24 hours) showed the highest strength and lowest density of 15.6 MPa and 1400 kg/m3, respectively. The thermal conductivity and thermal diffusivity of lightweight geopolymer are substantially lower with value of 0.63 W/mK to 0.83 W/mk and 0.26 mm2/s to 0.35 mm2/s, respectively. A potential new lightweight construction material can be produced by using low cost of foaming agent and easy to process for addition to geopolymer paste. The fly ash-based lightweight geopolymer produced in this work exhibit compressive strength in accordance to the standard for masonry lightweight applications at considerably lower curing temperature (80 °C).
      1  7
  • Publication
    Development of a robust Sn-Cu based lead-free solder paste
    ( 2019)
    Rita Mohd Said
    During services and/or storage, solder joint is frequently exposed to operational conditions such as temperature, mechanical load, and electrical current. These conditions increase the demand for solder material which has high performance value in physical, mechanical, electrical and thermal stability. Thus, this research was motivated to develop Sn-Cu solder paste for robust solder joint through micro-alloying, composite and transient liquid phase soldering (TLPS) approaches. The aims of this study are to investigate the thermal properties, the phases that exist, the solderability, the microstructure evolution and also the shear strength of the new robust Sn-Cu based solder paste. The thermal stability of each solder paste has been investigated by determining the intermetallic compound (IMC) growth kinetic during isothermal aging. Isothermal aging was conducted for 24, 240 and 480 hours at a temperature of 75, 125, and 150 °C respectively. The robust solder paste was synthesized by using Sn-0.7Cu (SC), Sn-0.7Cu-0.05Ni (SCN), Sn-0.7Cu-0.05Ni-1TiO₂ (SCNT) and Sn-10Cu (SC10) TLPS bonding system. Findings reveal the reduction of about 1.5°C - 33.5°C in undercooling of solder paste with third element addition; Ni, TiO₂, and 10Cu. Result also reveals the improvement in contact angle for about 1.3°, 14.9°, and 9.5° for SCN, SCNT and SC10 solder respectively. The addition of Ni and TiO₂helps in refining the microstructure which had improved the mechanical properties. Furthermore, the IMC formation for TiO2 reinforced solder paste has been suppressed for 13.9%. The lowest growth rate was presented by SCNT (0.280, 1.390 and 2.800 0 ms-1 at aging temperature 75, 125 and 150°C respectively) and the SCNT solder also displays the highest activation energy which was 37.35 kJmol-1 compared to the other solders. The thickening of interfacial IMCs thickness occurred with prolong aging time has caused a decreasing in shear strength for all solder joints. Nevertheless, the highest strength was observed in SC10 TLPS. Overall, owing to excellent in solderability, thin IMC thickness, finer microstructure, and high shear strength have proven the SCNT solder paste composite a potential solder interconnect to be applied in typical electronic assemblies. In addition, SC10 TLPS could be established as a promising candidate for TLPS solder alloy for high power electronic assemblies.
  • Publication
    Development of anodised aluminium oxide nanostructure from Al-Mn alloy
    ( 2013)
    Voon Chun Hong
    This study was divided into two parts. The first part of the study was focused on the synthesis of well ordered porous AAO by using oxide dissolution treatment. The porous AAO was formed by anodising of 99.99 % aluminium in 0.3 M oxalic acid at 15 oC for 15 minutes. Anodised substrates were subjected to oxide dissolution treatment by immersing in stirred mixture of chromic acid and phosphoric acid. The effect of oxide dissolution treatment on the morphology and regularity of porous AAO was studied by using scanning electron microscope. The results showed that exposure of porous AAO to oxide dissolution treatment up to three minutes revealed the well ordered pores arrangement that formed during the steady state growth stage. Regularity of the porous AAO was improved. In the second part of the study, porous AAO was formed from aluminium manganese (Al-Mn) alloy substrates and the effect of manganese content, anodising voltage, concentration of oxalic acid, and temperature of oxalic acid on the anodising behaviour, morphology, dimensional properties and growth kinetics were studied. Results showed that the addition of Mn from 0.5 wt % to 2.0 wt % into Al substrates reduced the current density, regularity and growth kinetics of porous AAO. The pore size and interpore distance were also found to decrease with the addition of Mn. Anodising efficiency of anodising process decreased as the Mn content increased up to 1.0 wt %, but increased when the Mn content was further increased to 2.0 wt %. Analysis of XRD patterns showed that amorphous alumina was formed in substrates of all compositions and MnO2 was found to present in Al-1.5 wt % Mn and Al -2.0 wt % Mn substrates. For the study of effect of anodising voltage, anodising of Al-0.5 wt % Mn under the influence of increasing anodising voltage of 30-70V has led to higher current density, larger pore size and interpore distance and higher growth rates. The regularity of pore arrangement of porous AAO was improved when the anodising voltage was increased from 30 V to 50V, but deteriorated when further increased to 70V. Dielectric breakdown occurred when anodising was conducted at 70V. Amount of amorphous alumina was found to increase when the anodising voltage was increased from 30 V to 70 V. Anodising of Al-0.5 wt % Mn at 50 V in oxalic acid of increasing concentration from 0.1 M to 0.7 M increased the current density and growth kinetics. Well ordered porous AAOs were obtained when oxalic acid of all concentration was used, except 0.1 M. Increase of concentration of oxalic acid decreased the pore size while no significant difference in interpore distance was observed. Anodising efficiency decreased as a function of concentration of oxalic acid. The relative intensity of broad peaks in XRD patterns showed that amount of amorphous alumina increased as a function of concentration of oxalic acid. For the study of effect of temperature of oxalic acid, anodising of Al-0.5 wt % Mn was conducted at 50V in 0.5 M oxalic acid of temperature ranging from 5oC to 25oC. Current density and oxide thickness increased while regularity of pores arrangement and anodising efficiency decreased with the increasing temperature of oxalic acid. Temperature of oxalic acid did not have obvious effect on both pore size and interpore distance. Relative intensities of broad peaks increased indicating the amount of amorphous alumina increased with the increasing temperature of oxalic acid.
  • Publication
    Development of composite cement reinforced with coconut fibre
    ( 2012)
    Alida Abdullah
    This research was conducted to develop cement composite with the addition of coconut fibre in cement panel. The raw materials used were Ordinary Portland cement, coconut fibre, sand and water. The development of cement composites in this research were done by substituting coconut fibre to the portion of sand based on the ratio of cement to sand. In this study, the ratios used to design the mixture were 1:1:0, 1:0.97:0.03, 1:0.94:0.06, 1:0.91:0.09, 1:0.87:0.12 and 1:0.84:0.15 (cement: sand: coconut fibre). The amount of water per cement ratio was fixed at 0.55 for each mixture ratio. The sizes of sample tested were, 160 mm x 40 mm x 40 mm for compression test, and 100 mm x 100 mm x 40 mm for density, moisture content and water absorption tests. The samples were cured in water for 7, 14, and 28 days. The result shows that the cement composite with 9 wt. % of coconut fibre gives highest flexural and compressive strength. It was found that by increasing the content of coconut fibre, the density of cement composite was decreased while the water absorption and the moisture content percentages were increased. This study also reports the fracture behaviour of composites after flexural test. It revealed the crack bridging had strengthened the composite.
  • Publication
    Development of kaolin geopolymer ceramic with addition of ultra high molecular weight polyethylene (UHMWPE) as binder for lightweight ceramics
    ( 2018)
    Romisuhani Ahmad
    A lightweight ceramic material displays physical, mechanical and structural features which is highly preferred in modern ceramic industry. Geopolymer technology has been involved in many applications including in the formation of ceramic. The transformation phase of geopolymer from amorphous to crystalline upon heating require a low processing temperature compared to the conventional ceramics. A major synthetic process for industrialised lightweight ceramics is to use additives which are organic in nature such as binders, plasticizers, surfactants and lubricants.This study investigated the use of geopolymer in producing ceramic materials where kaolin was used as main source material and Ultra High Molecular Weight Polyethylene was added as binder. In this study, the solid-to-liquid ratio of 1.0 and alkaline activator ratio of 0.24 were fixed. Kaolin geopolymer were then cured at 80 °C for 24 hours, the samples were then crushed into powder form. By using powder metallurgy method in producing kaolin geopolymer ceramic, three parameters used are sintering temperature (900 °C, 1000 °C, 1100 °C, 1200 °C), binder content (2 wt.%, 4 wt.%, 6 wt.%, 8 wt.%) and sintering method which are conventional and two-steps sintering method. The optimum weight percent of binder were studied by fixing the sintering temperature, while the optimum of sintering temperature were studied by fixing the weight percent of binder based on testing of flexural strength, density, shrinkage, and water absorption. The results indicated that kaolin geopolymer ceramic with the addition of 4 wt.% of Ultra High Molecular Weight Polyethylene sintered at 1200 °C using two steps sintering method could achieve an optimum strength of 94.32 MPa with a density of 1.71 g/cm3. Also a smooth surface and increasing in formation of pores were observed, which would facilitate the formation of the lightweight and strong structure. Then, the performance of kaolin geopolymer lightweight ceramic was examined by performing microstructural and mechanical properties tests. The outcomes revealed the possibility to produce a lightweight ceramic based kaolin-geopolymer with a considerable characteristics and mechanical properties, which could open the door for many applications in the future. Geopolymer based lightweight ceramic has been claimed as a promising material, due to its ability to produce a high-performance lightweight ceramic and because of its relevant environmental and economic benefits. Furthermore, lower-powered mechanical and thermal treatments are required to ensure the excellent properties and quality to produce the lightweight ceramic materials lead to a positive effect on the environment hence suitable with the desire for eco-friendly industry.
      1  5
  • Publication
    Development of lead-free Sn-0.7Cu-Si₃N₄ composite solders
    ( 2013)
    Muhammad Hafiz Zan @ Hazizi
    Lead based solder have been widely used before science have proven lead as one of the hazardous substances which can harm the environment and human health. With the banning usage of lead based solder as interconnect, various lead-free solders have been introduced and some of them are currently being widely used. However, none of them still can surpass the properties of a lead based solder, which keeps the researches on lead-free solder still going on and on. In this project, a new lead-free composite solder was developed by adding various amount of Si₃N₄ into Sn-0.7Cu solder via powder metallurgy route which consists of mixing compaction and sintering. Composite solder was used in order to enhance the properties of the conventional solder. The project was divided into two phases, where at Phase 1, the optimization of mixing, compaction and sintering were studied while at Phase 2, the composite solder were tested, analyzed and compared with the monolithic solder. Upon completion of both phases, the best amount of Si₃N₄ was added into Sn-0.7Cu will be proposed. Generally, the Sn-0.7Cu-Si₃N₄ composite solder showed improvement compared to the monolithic solder and it was finally decided that Sn-0.7Cu-0.5Si3N4 was the most preferable composite solder.
  • Publication
    Effect of chemical modification of eggshells powder filled low density polyetylene composites
    ( 2010)
    Siti Shuhadah Md Saleh
    Eggshells powder filled low density polyethylene (LDPE/ESP) composites were studied. The composites were prepared by using Z-blade mixer at 1800C using a rotor speed of 50 rpm for 6 minutes. Sample of composites were compression moulded, in an electrically heated Hydraulic press. Hot press procedures involved preheating at 1800C for 4 min followed by compression for 2 min at the same temperature and subsequent cooling under pressure for 2 min. It was found that the tensile strength and elongation at break for the composites decreased with the increasing filler loading. Young’s modulus for the composites increases with the increasing filler loading. Then the composites were modified with isophthalic acid (LDPE/ESPI), ethylene diamine-co-isophthalic acid (LSPE/ESPM) and polyethylene-grafted-maleic anhydride (LDPE/ESPPEMAH). It was found that improvement in interfacial adhesion has enhanced the tensile strength and water absorption resistance of LDPE/modified eggshells powder composites compare to LDPE/unmodified eggshells powder composites (LDPE/ESP).Its also increased thermal stability and percent of crystallinity of composites. Better interfacial adhesion between LDPE and eggshells powder are responsible for the improvement of mechanical properties of LDPE/modified eggshells powder composites, as evident by scanning electron microscopy (SEM) on tensile fracture surface of the composites.
      1  6
  • Publication
    Effect of different process parameters on the heat transfer of liquid coolant in electronic system
    ( 2017)
    Wan Mohd Arif W Ibrahim
    An effective heat transfer system is important for new technologies today to enhance the performance of heat transfer, especially, since the miniaturization of electronic system that resulted in dramatic increase in the amount of heat generated. In the case, where air cooling could not meet requirements, liquid cooling does offer significant cooling advantages over conventional air cooling because of its better thermal transfer property. But unsuitable selection of liquid coolants may result to low performance or problems to the cooling systems. This study investigates the effect of different process parameters on the heat transfer of the liquid cooling. Experimental investigations have been carried out for determining the cooling performance of distilled water, vegetable oil and alumina sols in cooling system of central processing units (CPU) at different parameters of input power and mass flow rate. Optimising the pH values is very crucial because it will determine the stability of alumina sols, an optimal pH value of pH 4 is obtained for the alumina sols. There is no significant effect to the viscosity of the alumina sols because of low concentrations of alumina particles are dispersed in base fluids. Input power is direct influence to the final temperatures of CPU block and fluids. The heat transfer coefficient of the fluids is improved and a clear decrease of the junction temperature between the heated component and the water cooling block due to the higher mass flow rate. Alumina sols show better heat removal capability and higher heat transfer coefficient than distilled water and vegetable oil due to the presence of alumina particles in the fluids. Experimental results emphasize the higher molarity of alumina sols contributes higher heat transfer coefficient. The heat removal capability of 0.1 M, 0.5 M and 1.0 M alumina sols have been found as much as 15.4 %, 32.3 % and 40.8 % higher than distilled water. This study recommend that a stable 1.0M alumina sol may be use as liquid coolant for CPU cooling system as well as in component test handlers in semiconductor industry.
  • Publication
    Effect of hybrid layered silicates/geopolymer fillers on properties of epoxy composites
    ( 2018)
    Yusrina Mat Daud
    Layered silicates are commonly used as filler materials in polymers including thermoset to improve the matrix’s mechanical, physical and barrier properties. Montmorillonite belongs to the class of layered silicates which has great potential as filler due to its high surface area and aspect ratio with thickness of each individual layer is about 1 nm. However, the use of montmorillonite as single filler has limitation in terms of assisting the matrix to achieve high mechanical performance when subjected to various mechanical loads (compression and flexural). Therefore, in this thesis, the use of hybrid fillers was investigated using organo-montmorillonite and geopolymer fillers to obtain epoxy based composite material with greater combination properties. Raw materials geopolymer filler used in this study is from Saudi Arabia. Based on characterization of these minerals resources, it indicates the suitability of being a geopolymer filler. The preparation of the composites and hybrid composites was conducted by mechanical shear mixing method at room temperature. The effect of the organo-montmorillonite and hybrid organo montmorillonite/geopolymer fillers addition on the epoxy was thoroughly studied by compressive and flexural tests, thermal analysis, X-ray diffraction analysis and water absorption test. Epoxy/organo-montmorillonite composite was prepared with varies organo-montmorillonite loading from 1 phr to 7 phr. Results demonstrated that optimum loading of organo-montmorillonite in epoxy was achieved at 3 phr loading. This finding has leads to development of hybrid composites using optimum organo-montmorillonite content and five types of geopolymer fillers (fly ash, kaolin, white clay, pozolonite and silica sand) with loading from 1 phr to 7 phr. However, among five types of geopolymer fillers, kaolin has presented the best compressive and flexural properties at about 36.65 MPa and 20.18 MPa. The data was supported by other analysis such thermogravimetry, X-ray diffraction, and dynamic mechanical analyses. Based on these research outcomes, it can be highlighted that the use of hybrid organo-montmorillonite/geopolymer fillers can more efficiently improve the strength, thermal stability and durability of the epoxy as compared to the single organo-montmorillonite filler. These improvement has led to the exploration of exciting fields and creating novel for the production of hybrid layered silicates/geopolymer filler in epoxy composites.
      2  18
  • Publication
    Effect of mixing condotions on the properties and characteristic of kaolin geopolymers
    ( 2014)
    Heah Cheng Yong
    Geopolymerization process utilizing kaolin as aluminosilicate source was performed. The goal of this study was to investigate the effect of NaOH concentration, S/L ratio, Na2SiO3/NaOH ratio, curing temperature and time as well as mechanical treatment of kaolin on kaolin geopolymers. The results showed that 8M of NaOH concentration, S/L ratio of 1.00, Na2SiO3/NaOH ratio of 0.32 and curing conditions at 60°C for 72 hours were the optimum mixing conditions for kaolin geopolymers synthesis. In order to increase the reactivity of kaolin towards geopolymerization reaction, mechanical treatment of kaolin was conducted through milling process. The optimum milling time of kaolin was 5 hours. Mechanical treatment of kaolin has successfully decreased the particle size and increased the surface area of kaolin particles, producing mechanicaltreated kaolin geopolymers with better compressive strength (9.58 MPa) compared to kaolin geopolymer synthesized with untreated kaolin (5.94 MPa). Bulk density measurement showed that kaolin geopolymers were lightweight (< 1870 kg/m3). During the geopolymers synthesis, workability must be taking into consideration since it affected significantly the strength development of kaolin geopolymers. Microstructural analysis (SEM) revealed that kaolin geopolymers only undergo low dissolution as shown by the presence of large amounts of unreacted kaolin particles in the microstructure of kaolin geopolymers. However, the formation of homogeneous geopolymer gel was observed at longer day of testing. Besides, elemental composition analysis (EDX) results supports the continuous development of geopolymer structure as indicated by the increased Na/Al and Si/Al ratios by the day of testing. Zeolites peaks appeared in kaolin geopolymers after the geopolymerization reaction as determined by phase analysis (XRD). The amorphous geopolymer and crystalline zeolite phases contributed to the strength of geopolymers. Even so, these crystalline zeolites peaks gradually decreased in intensity at longer day of testing and were found degraded the compressive strength of geopolymers. Functional group identification (FTIR) shows the formation of more geopolymer bonding in kaolin geopolymers at longer testing day. On the other hand, based on compressive strength results, the optimum oxide molar ratios of SiO2/Al2O3, Na2O/SiO2, H2O/Na2O and Na2O/Al2O3 for kaolin geopolymers synthesis were concluded at 3.28, 0.28, 14.61 and 0.92, respectively. In general, kaolin has low reactivity and it required more time for dissolution in alkaline activator solution and hence the formation of geopolymer structure. The slow rate of geopolymerization reaction led to a slow strength development of geopolymers. As a conclusion, this study provides a better understanding of the properties (compressive strength, workability and bulk density) and characteristic (microstructure, phases and functional groups) of kaolin geopolymers. Thus, for future research, it is suggested to increase the reactivity of kaolin towards geopolymerization reaction in order to improve the mechanical strength.
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  • Publication
    Effects of solution treatment temperature on the mechanical properties of commercial recycled aluminium alloy cylinder head (A319)
    ( 2010)
    Murizam Darus
    The present work was performed to investigate the effect of different solution treatment temperature on commercial recycled aluminium alloy cylinder head during artificial ageing process. All samples were sectioned from recycled automotive cylinder head and solution heat treated at 495°C, 510°C and 525°C each for a period of 10 hours. All samples were then quenched into ice water at 0°C and followed by artificial ageing at 180°C for a time up to 20 hours. The precipitation behaviours was monitored by Vicker’s microhardness test and electrical resistivity measurement. Precipitation occurrence were characterised by thermal analysis method and SEM/EDX technique on critical sample. The effect of heat treatment processes was observed by metallographic technique. It is seen that the aluminium alloy exhibit age hardening response similar to artificial ageing where as the the peak-age hardening accelerated when higher solution temperature applied. The hardening effect achieved was due to precipitation of metastable phases of θ˝/θ΄, β˝/β΄, and Q˝Q΄ except for 495°C where the coarser silicon particles contributes to the peak-aged hardening. Silicon particle were fragmentised and spherodised during high temperature solution treatment and homogenised into the aluminium matrix. Prolonged artificial ageing resulting the silicon particles to growth and reduces the nucleation site for phases precipitation, thus reduce the aluminium alloy hardening.
  • Publication
    Enzymatic assisted Citronella essential oil extraction from Cymbopogan Winterianus
    ( 2015)
    Norhidayah Abd Aziz
    The essential oil of Citronella is commonly extracted via typical steam distillation of citronella plan parts. However, the oil yield is generally low (0.22% - 1.0%), causing burden to many entrepreneurs to meet the strong demand. Therefore, the study was conducted to improve the yield of citronella oil recovery by introducing an optimised enzymatic assisted pre-treatment using crude microbial enzymes isolated from the soil surrounding the citronella roots. Firstly, the lignocellulosic components of dried citronella roots were investigated to evaluate the most abundance component for selection of enzymes useful for pre-treatment. The composition analysis has identified cellulose as the major lignocellulosic component (38.21%±1.65), followed by hemicellulose (30.49%±0.93), lignin (21.12%±1.86) and extractives (4.97%±0.22). 31 out of 52 isolated strains have been identified as positive cellulase producer. Based on the calculated cellulolytic indexes, 4 strains i.e; UniMAPF7, UniMAPF16, UniMAPF24, and UniMAPF27 were selected for application in the laboratory scale pre-treatment process. Results from the growth curve analysis and enzyme activity study suggested that the optimal time for enzyme harvesting occurred at day 5 for UniMAPF7, day 4 for UniMAPF24 and day 3 for UniMAPF16 and UniMAPF27. Laboratory scale oil extraction of pre-treated citronella root with crude enzymes of UniMAPF7 and UniMAPF24 yielded in a significant 2.5-fold and 1.7-fold increased in citronella oil recovery, respectively, when compared to the untreated citronella root as control.
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  • Publication
    Fabrication and characterization of hybrid microwave assisted sintering Sn-0.7Cu + 1.0wt.% Si₃N₄ composite solder
    ( 2015)
    Flora Somidin
    One of the leading choices in upgrading the properties of existing lead-free solder alloys is by composite technology approach, whereby high technical ceramic particles can be added into the solder alloy matrix. Accordingly, Sn-0.7Cu + 1.0wt.% Si₃N₄ composite solder was synthesized using powder metallurgy routes which consist of blending, compaction and sintering. This research introduced a hybrid microwave assisted sintering process which can sinter ceramic-reinforced composite solder at approximately 185˚C within 2 minutes without holding time and protective inert gas. In order to evaluate the compatibility of hybrid microwave assisted sintering approach in ceramic-reinforced composite solder development, a detailed comparison of the process and properties of conventionally sintered and microwave sintered samples of Sn-0.7Cu + 1.0wt.% Si₃N₄ composite solder was performed. Identical sintering temperature at 185 ˚C was used for both types of sintering, in which conventional sintering was performed using a tube furnace in an argon atmosphere for 2 hours. The monolithic Sn-0.7Cu solder sample was also synthesized as control sample in a similar way. Hybrid microwave assisted sintering method showed significant advantages in processing compared to conventional sintering method, such as rapid heating rate, shortened sintering time, less energy consumption and much less expensive equipment. The influence of different sintering methodologies on Sn-0.7Cu + 1.0wt.% Si₃N₄ bulk solder sample were investigated based on the density, porosity, microhardness, microstructures, wettability and intermetallic compound thickness on Cu-substrate. It was noted that microwave sintering method can densify the Sn-0.7Cu + 1.0wt.% Si₃N₄ composite bulk solder green compact in a short time, however, conventional sintered sample showed better density and porosity. Interestingly, finer and well-distributed precipitates were observed in microwave sintered samples. This has led to higher microhardness performance observed in microwave sintered sample (12.0 ± 0.2 HV) compared to the conventionally sintered sample (11.2 ± 0.1 HV). The wettability performance of Sn-0.7Cu + 1.0wt.% Si₃N₄ composite solder on Cu-substrate was slightly reduced with microwave sintering approach, however, insignificant difference of intermetallic compound thickness was observed in both microwave sintered and conventionally sintered samples. Overall, hybrid microwave assisted sintering showed better processing with promising properties on ceramic-reinforced Sn-0.7Cu + 1.0wt.% Si₃N₄ composite solder.
      4  10
  • Publication
    Fabrication and properties of Cobalt-Chromium implant composite
    ( 2007)
    Nur Hidayah Ahmad Zaidi
    Cobalt implant composite (CIC) was produced by powder metallurgy technique. Composition of 0% ,5%, 10%, 15% and 20% of hydroxyapatite was mixed with cobaltchromium alloy. The fabrication technique is mixing, blending, pressing and sintering of the final product. Cobalt, chromium and hydroxyapatite powders were mixed in planetary ball mill at 600 rpm for 30 minutes. The consolidation method for CIC was uni-axial compacting using Universal Testing Machine (UTM) Gotech. The pressure used was 500 MPa. The CIC was sintered at 10000C temperature with 200C/min for 3 hours. The composites then were evaluated and tested to evaluate the microstructure and mechanical properties. The microstructure analysis is carried out by using the Scanning Electron Microscope and Image Analyzer attached to the optical microscope. In microstructure analysis, there are several characteristics need to observe i.e., particle sizes, porosities, mode of shapes, corrosion behaviours and bonding between mixed particles and fracture mechanism, which these can describe the composites material in details. The properties such as hardness, density, and particle sizes distribution, purity of raw materials, compressive strength and corrosion behaviours are analyzed by using Vickers Micro Hardness, AccuPyc 1330 Gas Pycnometer, MALVERN MASTERSIZER 2000 particle analyzer, X-Ray Diffraction (XRD), Compression test and Immersion Fluid test in Natrium Chloride (0.9%.NaCl ), respectively. From the microstructure analysis of the composite, the microstructure indicates the homogenous distribution of the chromium particles, and HAP particles are distributed homogenously in the matrix cobalt chromium. From the X-ray diffraction (XRD) the high peak of the x-ray analysis is indicating the purity of each powder such as chromium and cobalt. In general cobalt and chromium peaks occur at the range of 40 to 50 degree and there is no obvious sign of HAP signal in XRD analysis of the composites. Both experimental and theoretical density graphs have shown a similar pattern line which both experienced the density gradually decreased when percentage of HAP increased. The hardness of the composites decreases slightly with the increasing weight percent of HAP. The sonic modulus analysis, indicating that there is a reciprocate relationship between modulus and sound velocity, whereby modulus will be decreased when the sound velocity increases. The microstructure analysis on compression test, indicated the deformation behavior of the composite started to change from the ductile mode to the brittle mode resultant with the added of HAP. Besides, the crack pattern showed non continuously for the ductile mode behavior and had a continuous line for the brittle mode behavior. Corrosion study indicated that composites experienced more corrosion when the HAP was added.
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