Theses & Dissertations

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  • 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.
      1  3
  • Publication
    Pencirian dan potensi Dolomit Perlis sebagai pengisi dalam produk komposit Termoset
    ( 2007)
    Mohd Nazry Salleh
    Dolomit merupakan sejenis mineral yang didapati dengan banyaknya di negeri Perlis. Negeri Perlis merupakan antara pengeluar terbesar dolomit di Malaysia. Kajian ke atas dolomit dilakukan untuk menambah nilai dolomit ini kepada potensi kegunaan yang lebih efisien. Dolomit Perlis yang digunakan dalam penyelidikan ini diperolehi daripada pembekal Tasuh Kuari Sdn. Bhd. Pencirian dolomit Perlis dilakukan dengan menggunakan peralatan Malvern Mastersizer bagi analisis saiz partikel, kajian morfologi menggunakan SEM dengan dilengkapi penganalisa spektrometer serakan tenaga sinar-X (SEM-EDS), penentuan fasa mineral dengan menggunakan XRD, analisis komposisi kimia menggunakan XRF dan analisis terma menggunakan TGA. Selain itu, sifat-sifat fizikal dolomit Perlis ditentukan melalui analisis ketumpatan pukal dan ujian keliangan, analisis penyerapan air dan ujian kehilangan pencucuhan. Daripada analisis yang dijalankan, unsur utama yang terdapat pada dolomit adalah kalsium dan magnesium. Kajian morfologi menunjukkan dolomit Perlis dan dolomit Ipoh mempunyai bentuk yang tidak seragam dan cenderung untuk membentuk pecahan pada butiran yang tidak seragam itu. Penentuan fasa mineral yang hadir pada dolomit Perlis ialah kalsium magnesium karbonat, CaMg(CO3)2 dalam sistem kristal trigonal-rombohedral dan kumpulan ruang ialah R-3. Corak belauan sinar-x bagi sampel dolomit Perlis dan dolomit Ipoh didapati hampir sama dan ini menunjukkan persamaan dari segi strukturnya. Analisis terma menggunakan analisis termogravimetrik (TGA) menunjukkan dolomit Perlis akan mengalami penguraian pada dua peringkat apabila dikenakan suhu yang tinggi. Pada peringkat pertama penguraian ini berlaku pada suhu 752.54 °C dan diikuti dengan peringkat kedua iaitu 930.52 °C. Berdasarkan analisis XRF yang dijalankan, dolomit Perlis mengandungi komposisi utama 31.5 % kalsium oksida (CaO) dan magnesium oksida (MgO) sebanyak 22.65 %. Dolomit Perlis juga mengandungi komposisi logam-logam oksida seperti aluminium oksida (Al2O3), ferum oksida (Fe2O3), silikon oksida (SiO2) dan natrium oksida (Na2O). Ketumpatan pukal bagi sampel dolomit Perlis dapat ditentukan dengan menggunakan prosedur ASTM C373 daripada prinsip Archimedes dan menunjukkan bacaan ketumpatan pukal adalah 2.7146 g/cm3. Dolomit Perlis secara semulajadinya adalah bahan berongga dengan pelbagai darjah keliangan. Keputusan daripada ujian keliangan menunjukkan peratusan bagi keporosan sebanyak 1.27 % manakala peratusan kehilangan pencucuhan oleh sampel dolomit Perlis adalah 28.31 %. Potensi dolomit Perlis sebagai pengisi alternatif yang murah dan mesra alam sekitar di dalam termoset epoksi turut dikaji. Penghasilan komposit menggunakan dolomit Perlis sebagai bahan mentah yang utama dan resin epoksi sebagai pengikat menggunakan konsep komposit muatan berpengisi tinggi. Penentuan sifat-sifat bagi termoset epoksi terisi dolomit Perlis melibatkan pengujian mekanikal seperti ujian hentaman, ujian pelenturan dan ujian tegangan. Daripada eksperimen yang dijalankan didapati sampel C mencatatkan bacaan kekuatan hentaman yang paling tinggi iaitu 1133.33 J/m. Kekuatan pelenturan dan modulus pelenturan menurun dengan penurunan saiz pengisi yang dimasukkan dalam penyebatian komposit manakala nilai kekuatan tegangan dan modulus tegangan meningkat dengan peningkatan saiz pengisi yang digunakan. Peratusan bagi pemanjangan pada takat putus sampel C menunjukkan peningkatan iaitu 4.65 % dengan penurunan saiz pengisi yang digunakan. Ujian pembakaran dalam relau mendapati sampel B memberikan penyusunan yang optimum antara resin dan pengisi. Ini dapat dibuktikan oleh mikrograf SEM di mana sampel B memberikan interaksi pengisi dan matriks yang lebih baik.
      1  26
  • Publication
    Corrosion behaviour on AA2014/15vol. %A1₂0₃P and AA2009/20vol. %SiCw composite after ageing treatment
    ( 2007)
    Zamri Yusoff
    The purpose of this study is to compare the corrosion behaviour between AA2014/15vol. %A1₂0₃P and AA2009/20vol. %SiCw composites after ageing treatment. The former composite was cast composite supplied by Duralcan USA. The later composite was a powder metallurgy composites supplied by Advanced Composite Materials Corporation USA. The corrosion behaviour was investigated by means of immersion test and salt spray test. Before immersion test, the composites were examined for ageing response at 16SoC (0 - 12hours). Microstructure evaluation has been characterized using optical microscope, SEM and EDX. It was observed that the distribution of SiC whiskers in the matrix AA2009 is more homogeneous compared to the distribution of Ah03 particles in the matrix AA2014. The secondary phases such as AhCu and AhCuMg were identified in AA20141l5vol. %A1₂0₃P whereas AhCu was identified in AA2009/20vol. %SiCw composites after ageing. Localized corrosion is more intense in AA2014/15vol. %Ah03p compared with AA2009120vol. %SiCw• The pit shape for composite of AA20141l5vol. %A1₂0₃P is shallow wide pit and differs to composite AA2009/20vol. %SiCw which is shallow deep pit. Salt spray test has been used to assess the corrosion behaviour of the surface of as received composites. The corrosion product has been analysis using XRD after salt spray test. The qualitative diffraction pattern from both composites after 20 hours exposure in salt spray test shows the formation of the corrosion products. It was observed that three corrosion products were identified such as Mg (OHh, A1203, Mn02 in composite AA2014/15vol. %A1₂0₃P and no corrosion product was identified for composite AA2009/20vol. %SiCw.
      3  11
  • Publication
    Selective extraction and separation of Cu(II), Zn(II), Ni(II) and Fe(III) from the leach liquor of Printed Circuit Board using Cyanex 272 coated microcapsules
    ( 2008)
    Md. Sohrab Hossain
    The main purpose of this study was to recover and extract Cu(II) in presence of Zn(II), Fe(III) and Ni(II) from the leach liquor of Printed Circuit Board (PCB) using polystyrene microcapsules coated with Cyanex 272 (MCXs). MC-Xs were prepared following the solvent evaporation method at different conditions, and optimization conditions for the preparation of MC-Xs were evaluated. At first, the liquid-liquid extraction behavior of Cu(II) from acidic sulphate-acetate medium by Cyanex 272 diluted in hexane was investigated as a function of equilibrium pH, aqueous phase concentration of Cu2+, and Ac − Ο24 S -, and Cyanex 272 concentration in the organic phase. Results showed that the extraction performance was highly dependent on pH, Cyanex 272 concentration and Ac- concentration and suggested that the extracted species is [Cu(HA2)(Ac).2HA]. Batch extraction studies were carried out from the sulphate-acetate medium for both simultaneously and single metal extraction system using MC-Xs as a function of contact time and equilibrium pH for simultaneous extraction, and amount of MC-Xs, Cyanex 272 to Polystyrene ratio (Cyanex 272/PS) and PS to Cyanex 272 ratio (PS/Cyanex 272) in dispersed phase and Cu(II) ion concentration in aqueous phase for the single metal extraction. It was observed that the pH value of the feed solution played an important role for successful separation of the metal ions. Simultaneous metal ions uptake and separation efficiency of Cu(II), Zn(II), Fe(III) and Ni(II) were investigated using MC-Xs with packed column at different pH (2-5), illustrating that within this pH range, Ni(II) uptake was nil, almost 100% at pH 4 for the Zn(II) and Fe(III), whereas Cu(II) uptake was 26% at pH 5. The separation efficiency of Cu(II) was higher over other metal ions. But, the separation efficiency Zn(II) over Fe(III) was quite low. Stripping of Cu(II), Zn(II) and Fe(III) was carried out from the loaded MC-Xs using different concentration of sulphuric acid solution at solid to liquid ratio (S:L) of 1:10 showing that almost 100% stripping was obtained at 0.1 M H2SO4 solution for the Cu(II) and Zn(II) and 0.5 M H2SO4 solution for the Fe(III). The regeneration experiment showed that the microcapsules have sufficient stability for the metal ions extraction. Factorial design and Yates’ analysis of experiment was carried out for the optimization and evaluation of the main effects and interactions of the Cu(II) extraction factors in the presence of Zn(II), Fe(III) and Ni(II) using MC-Xs at two different experimental conditions. Factorial design and Yates’ analysis was also carried out in order to determine the optimum condition of stripping factor for the stripping of Cu(II) from loaded MC-Xs using sulphuric acid solution.). Finally, A complete process for the separation and recovery of Cu(II), Zn(II), Fe(III) and Ni(II) was carried out from the leach liquor of PCB following the batch extraction process based on the batch extraction using MC-Xs. The process showed the selective recovery of 99.22%, 77.57% and almost 100% for the Cu(II), Zn(II) and Ni(II), respectively.
      5  3
  • Publication
    Unsaturated polyester composites filled with untreated and surface treatment sugarcane bagasse by hot press technique
    ( 2009)
    Muhammad Salihin Zakaria
    The aim of this research is the improvement of the mechanical properties of natural fiber reinforced thermoset, as a result of optimization of the properties of sugarcane bagasse fibers by the use of NaOH treatment process. Tert-butyl perbenzoate was used as catalyst at elevated temperature for efficient processing of polyester composites. Sugarcane bagasse fibers were alkalized with 1, 3 and 5% NaOH solution, combined with four different fiber loading formulation, and hot-pressed to form natural fibers composites. The flexural modulus and strength of bagasse fiber composites alkalized with 3% NaOH solution gave the highest value and the untreated bagasse fiber gave the lowest. The same trend was obtained for the tensile modulus and strength as expected. However, by increased the NaOH solution, the mechanical properties decreased as a result of fibrillation lead to uneffective stress transfer occurred. Meanwhile, the break elongation of composites was decreased due to the improved fiber-matrix adhesion (to give more stiffness to the composites). Dynamic mechanical analysis (DMA) showed that with 3% NaOH solution treatment, bagasse fiber composites gave the highest storage modulus (E′) values and the lowest tan δ values. SEM observations on the fracture surface of composites showed that the surface modification of the fiber occurred and improved fiber-matrix adhesion. A water absorption test also showed that with 3% NaOH solution treatment, bagasse fiber composites gave higher bonding and adhesion compared to all another bagasse fiber composites.
      2  3
  • Publication
    Corrosion behaviour on powder metallurgy aluminium matrix composite reinforced with alumina Saffil™ short fibres
    ( 2009)
    Normah Cheman
    The corrosion behaviour of PM Al composite will be affected by the presence of alloying element and reinforcing phase in the composite. This studies were focused on the influence of magnesium addition and alumina Saffil™ short fibres reinforcement on corrosion behaviour of PM AMCs. PM Al composite and PM Al-Mg composite were fabricated from flaky aluminium powder, granular magnesium and alumina Saffil™ short fibres with an average particle size of 70.58 µm, 273.41 µm and 16.71 μm, respectively. The experimental parameter were maintained the content of magnesium powder (ranging from 0.5 wt% to 3.0 wt%) and alumina Saffil™ short fibres (ranging from 5 wt% to 25 wt%) . The samples were fabricated by using 200 MPa uniaxial pressing and sintered in argon atmosphera for 6 hours. Sintered samples were characterized by using SEM, density and porosity analysis and Vickers hardness testing. The optimum samples were tested in corrosion properties by using electrochemical test and immersion test. Both experiment using 3.5 wt% NaCl as corrosion environment. Electrochemical test was carried out with apply potentiostat Gamry G300 to create Tafel plot and polarization curve. The immersion test was carried out for 28, 56 and 84 days. Weight loss curves were acquired from immersion test results. Photomicrographs of samples were examined using scanning electron microscopy (SEM). The elemental composition of sample was analyzed by Energy dispersive X-ray (EDX) analysis. The presence of an oxide phases were verified by X-ray diffraction analysis (XRD). Experimental results showed the wetability between alumina Saffil™ short fibres and Al matrix have been improved by adding magnesium in the PM Al composite. PM Al – 15 wt% Al2O3 and PM Al – 2 wt% Mg - 15 wt% Al2O3 were identified as the optimum sample. The corrosion rate of PM Al composite was decreased from 67.69 µm/year to 0.66 µm/year when 2 wt% of magnesium was added in PM Al-Mg composite. SEM photomicrograph observed that pitting was localized surrounding the magnesium constituents which occur randomly throughout the surface of PM Al-Mg composite. XRD analysis revealed that aluminum oxide (δ-Al Al1.67O4), aluminium hydroxide (Al (OH)3) and aluminium oxide (α-Al2O3) phases were detected in oxide film. The critical current density (Icrit) of PM Al composite is lower than PM Al-Mg composite which is 2.0 x 10-1 A/cm2 and 4.0 x10-1 A/cm2, respectively. Magnesium is used as inhibitor in corrosion behaviour of PM Al-Mg composite have been changed and protected with a stable formation of oxide film. The corrosion resistance of PM Al-composite was decreased with the presence of alumina Saffil™ short fibres in composite due to discontinuities in oxide film provided the corrosion initiated in sample.
      3  12
  • Publication
    Refuse-derived plastic from waste expanded polystyrene and used deep-fried oil
    ( 2009)
    Noor Aishatun Majid
    A refuse-derived plastic was produced by mixing waste Expanded Polystyrene (EPS) in solution with used deep-fried oil (UDFO). A measured amount of methyl ethyl ketone peroxide (MEKPO) was added as a reaction initiator and cobalt-naphthenate as a promoter. Investigation of solubility test of EPS in MEK solvent indicates that 5 g waste and EPS 10 g MEK were found to be an effective mixture to make the best formulation in making refuse-derived plastic. Experiments on preparation of refuse-derived plastics with different amount of used deep-fried oil and Polystyrene in MEK solution indicates that 15 wt. % of UDFO cooperated well with waste EPS and resulted the highest tensile strength and maximum stress (flexural strength) 3.579 MPa and 6.520 MPa. The morphology and performance characteristic of the prepared waste expanded polystyrene (EPS) based plastic filled with 15 wt. % used deep-fried oil (UDFO) and 15 wt. % fresh oil (FO) were determined and compared. The tests showed that the prepared refuse-derived plastic has some advantages such as excellent tensile strength, elongation at break, modulus of elasticity and flexural strength compared with waste expanded polystyrene (EPS) based plastic filled with 15 wt. % with fresh oil (FO).
      11  4
  • Publication
    Characterization and mechanical properties of coconut shell filled acrylonitrile butadiene styrene / ethylene propylene diene monomer composites
    ( 2009)
    Siti Noorkhartina Ishak
    Coconut shell filled ABS/EPDM composites were prepared using a Z-blade mixer at processing temperature 2000C and rotor speed 50rpm.Effect of chemical treatment,different composition of blend ratio , different filler loading and effect of thermal aging on mechanical, thermal, and morphological properties of coconut shell filled ABS/EPDM composites was investigated.Maleic acid (MA) were used to treat the fiber surface.The increasing composition of EPDM will decrease the tensile strength and Young’s modulus but increasing in elongation at break.The increasing in filler loading and the presence of maleic acid increase the tensile strength and Young’s modulus but decrease the elongation at break is decreased.Result after thermal aging shows the same trend but lower than before aging.Morphological investigation using SEM revealed that the improvement in tensile strength and Young’s modulus was due to enhancement of the interfacial adhesion between coconut shell and ABS/EPDM. The thermal stability of coconut shell filled ABS/EPDM blends improved with the presence of MA.
      3  1
  • Publication
    A new development of modified dipping process of the prevulcanized natural rubber latex films: investigation on the tensile and swelling properties.
    ( 2009)
    Noor Marlyna Ismail
    Prevulcanized natural rubber latex films were produced by modified dipping process and their tensile and swelling properties were investigated. Two type of natural rubber latex which is high ammonia (HA) and low ammonia (LA) latex. This research study is divided into three main parts. The first part of this research is mainly to determine the most suitable maturation time for the latex compound. Therefore, each type of latex was matured into three different maturation time, i.e., 1 hour, 3 hour and 24 hour. The latex compounds were further matured in water bath at temperature of 70°C until chloroform number 3 is achieved, in which indicates that coagulum is a non-tacky agglomerates. At this stage, the latex compound is considered moderately vulcanized. Then, the latex compounds were underwent coagulant dipping process and followed by curing/ drying at room temperature, stripping and testing. Results of the tensile test show that tensile strength and tensile modulus (M100 and M300) is increase whereas elongation at break decrease with increasing filler loading, with maturation parameter at 24 hour has shown the highest value for all tensile properties, followed by 3 hour and 1 hour. At similar filler loading, HA latex shows better tensile properties than LA latex. The second part involves the investigation on different curing time and temperature of the latex. The latex compounds were prepared as same method as in the part one with maturation time is 3 hour. The 3 hour maturation was chosen because the process is become more effective in term of time consuming. After that, the dipped compounds were vulcanized in the oven at two different processes. The first oven was set at lower temperature than the second oven, and variables with time. From the tensile test results, this part exhibits that the curing temperature at 70°C and 80°C for Oven A and Oven B, respectively, with curing time of 10 minutes for each oven shows better properties than other curing parameters. For last part, every sample in part one and two were underwent leaching process. The leached latex samples were then tested their tensile properties. At the same time, the vulcanized latex also prepared by modified dipping process in which the dipped compounds were vulcanized in the oven and then proceed with the vulcanization in the water bath. Finally, the cured-leached latex samples were dried at room temperature for 25 hours before testing. The results of modified dipping process latex samples show better tensile properties than samples in part one (vulcanized at room temperature) and part two (vulcanized in oven). Overall, crosslink density increases/ higher with increasing filler loading, maturation time and by using HA latex. The crosslink density is also higher for samples that vulcanized by modified dipping process than vulcanized at room temperature and in the oven.
      2  3
  • Publication
    Application of chitosan biopolymer as a sensing material
    ( 2009)
    Roshida Mustaffa
    The chitosan solution has been succesfully deposited on the silicon wafer using sol-gel method to fabricate the chitosan thin film sensors. The effect of different annealing temperature and annealing time to their electrical characteristics were studied without and under light illumination. The current-voltage (I-V) characteristics showed that sensitivity of chitosan thin film sensors depend on the annealing temperature and annealing time. For the annealing temperature effect, it was found that the film annealed at 190oC has the highest photocurrent compared to the others. While for the annealing time effect, it was shown that the higher annealing time, the higher photocurrent. The changes of photocurrent are related to the different microstructure of chitosan thin film sensors. Although, the photocurrent values of the films illuminated with light exhibit the fluctuation to the photocurrent values without light illumination. Overall the chitosan thin films are sensitive to the visible and UV light. Therefore, they have a good potential as thin film light sensors.
      2  5
  • Publication
    Characterization and properties of calcium carbonate filled polypropylene (PP) / ethylene propylene diene terpolymer (EPDM) composites
    ( 2009)
    Siti Rohana Ahmad
    Composites of thermoplastic elastomer blend of polypropylene (PP) and ethylene propylene diene terpolymer (EPDM) reinforced calcium carbonate (CaCO3) was investigated. All the composites were prepared by using Z-blade mixer at 180oC and rotor speed 50 rpm. The effect of filler loading of calcium carbonate filled PP/EPDM composites on mechanical properties, water absorption, morphology and thermal properties were studied. In general, increased of calcium carbonate loading have increased the value of modulus of elasticity, water absorption, thermal stability, whereas tensile strength, elongation at break and crystallinity of composites reduced. A compatibilizer, (MAPP) or coupling agent, (3-APE) was used to improve the mechanical properties of composites. The presence of MAPP or 3-APE improved the tensile strength, modulus of elasticity, thermal stability and crystallinity composites, whereas elongation at break and water absorption reduced. Results from scanning electron microscope (SEM) show that fillermatrix interaction was improved with incorporation of MAPP or 3-APE. The effect chemical modification of calcium carbonate with acrylic acid (AA) in PP/EPDM composites increased the tensile strength, elongation at break, modulus of elasticity, thermal stability and crystallinity composite but water absorption reduced. The micrograph SEM showed the treated composites with acrylic acid has better dispersion in PP/EPDM matrix. Effects of dynamic vulcanization on the properties of PP/EPDM/CaCO3 composites exhibit higher tensile strength, elongation at break and modulus of elasticity but lower water absorption. The SEM study of tensile fracture surface of dynamic vulcanized composites show interfacial interaction between calcium carbonate and PP/EPDM matrix has been improved. The dynamic vulcanized composites also exhibit better thermal stability and higher crystallinity.
      5  3
  • Publication
    A study on the potential of polystyrene lightweight aggregate in concrete
    ( 2009)
    Fetra Venny Riza
    Economic reason caused the used of expandable polystyrene increasing every year. The consequence is that the polystyrene wastes also mounted day by day. On the other hand, the source of natural aggregate is non-renewable. Public awareness to save the environment is always be campaigned through all kind media to reuse, reduce or recycle. This research comprised the effort to produce lightweight aggregate concrete from waste expandable polystyrene or also known as polystyrene foam that can be found easily around our neighborhoods as electronic packaging. The polystyrene lightweight aggregate was produce on reducing the size into several mm and prior to heat treatment at temperature ranging from 130°C to 180°C. Characterization of this polystyrene lightweight aggregate were done by several experiments that includes shrinkage measurements, bulk density, water absorption level, compressive strength, also utilized the observation of light microscope, scanning electron microscope, even just visual observation by human eye. In this work, the polystyrene lightweight aggregate product was incorporated in concrete. Concrete characterization was conducted similar to those for aggregate with additional the slump test, compression test and flexural test. The results showed that the best temperature to produce aggregate with highest compressive strength 69.2 MPa was 170°C where the water absorption levels only 2.4% and its bulk density 154.6 kg/m3. This result of bulk density satisfied the classification of lightweight aggregate concrete according to ASTM C330. Unfortunately, this lightweight aggregate concrete compressive strength only 9.8 MPa was not reached the requirements strength for structural concrete which is 17 MPa for 28-day compressive strength. Thus, the used of this polystyrene lightweight aggregate concrete limited for non structural purpose only.
      3  2
  • Publication
    Properties of water hyacinth fibers (Eichhornia crassipes) filled low density polyethylene/acrylonitrile butadiene styrene composites
    ( 2009)
    Ahmed Saleem Oleiwi Al-Khuzaie
    The water hyacinths are largely available in local rivers. In this research, the water hyacinth fibers have been used as reinforcing components for low density polyethylene (LDPE) and acrylonittile butadiene styrene (ABS). The chemical treatment using Isophorone diisocyanate (IPDI) and 1, 4-butanediol were carried out to modify the fiber properties. The effect of filler loading and IPDI-polyol as a coupling agent on mechanical properties, morphology, swelling behavior, thermal properties and thermal degradation were investigated. The composites were prepared by using Z-blade mixer at processing temperature 200 0C and rotor speed 50 rpm and mixed samples were then compressed by using a hydraulic hot press at the same temperature to form sheet samples composites. Generally, the results indicated that LDPE/ABS/WHF composites with IPDI-polyol as a coupling agent showed better mechanical properties and water absorption resistance than LDPE/ABS/WHF composites without IPDI-polyol. Micrograph of tensile fractured surface shows that the properties of modified fibers composites have better filler dispersion in matrix and embedded fiber into the matrix compared to unmodified fiber composites. It was also found that the modified WHF offers better thermal stability in the LDPE/ABS/WHF composites than unmodified LDPE/ABS/WHF composites.
      4  9
  • Publication
    Properties of eggshell powder filled low density polyethylene/ acrylonitrile butadiene styrene composites
    ( 2009)
    Mohammed Jasim Mohammed Al-Jumaili
    Eggshell powder is one of the most abundant materials on our planet and has been quite early used in ground form to produce polymer composites. Chemical unmodified and modified eggshells powder filled low density polyethylene and acrylonitrile butadiene styrene composites were studied. The compositions of LDPE/ABS/ESP with and without coupling agent were fixed which is the total weight are 120g per formulations. The composite was melt mixed at temperature of 200℃ and rotor speed of 50 rpm. Afterwards, the blend was compression molded in an electrically heated hydraulic press and was preheat at temperature for about 7 minutes and heated temperature about 4 minutes and cooled for 4 minutes. It was found those LDPE/ABS/ESP composites with N-acetyl N,N,N-trimethyl Ammonium Bromide as a coupling agent exhibit higher mechanical properties; tensile strength increased while elongation at break were decreased. Swelling behavior analysis shows that the composites with coupling agent had more water absorption. The differential scanning calorimetry analysis shows that the glass transition temperature, Tg and melting temperature, Tm of the modified LDPE/ABS/ESP composites increased. The Thermogravimetry analysis shows that the T-50% wt, final decomposition temperature and residual mass for modified compositions increased with increasing filler loading. The scanning electron microscopy (SEM) analysis shows that the modified LDPE/ABS/ESP composites has more tear line and rough tensile fracture surface than unmodified LDPE/ABS/ESP composites. The X-ray diffraction (XRD) analysis exhibited the d-spacing in the modified LDPE/ABS/ESP composites have higher than the unmodified LDPE/ABS/ESP composites, the interlayer distance decreased with increasing the filler loading.
      4  2
  • Publication
    Characterization and properties of palm kernel shell reinforced polyester composites
    ( 2009)
    Nor Mazlina Abdul Wahab
    Composites of unsaturated polyester (UP)/palm kernel shell (PKS) have been prepared by hand lay-up technique. The effect of filler loading of UP/PKS composites on mechanical properties and morphology were studied. Tensile and flexural tests have been done to determine the effect of filler loading on mechanical properties. The results showed the increased of PKS filler loading have decreased the value of tensile and flexural strengths, but increased in tensile modulus and flexural modulus. A coupling agent (3-APE) was used to improve the mechanical properties of composites. The presence of 3-APE improved the tensile strength, flexural strength, tensile modulus and flexural modulus. The study of scanning electron microscope (SEM) shows that the filler-matrix interaction was improved with incorporation of 3-APE. The effect of chemical modification of PKS with acrylic acid (AA) in UP/PKS composites increased the tensile strength, flexural strength, tensile modulus and flexural modulus. The SEM micrograph showed the treated composites with AA has better dispersion in UP matrix. FTIR spectra show the interaction between PKS and matrix was enhanced with addition of coupling agent.
      3  8
  • Publication
    High temperature corrosion behaviour of austenitic stainless steel with CaCO₃ and MgCO₃ deposit
    ( 2009)
    Habsah Md Ishak
    The high temperature corrosion behaviour of austenitic stainless steel was studied at 850°C, 900°C, 950°C and 1000°C for 24 to 120 hr exposure time with CaCO₃ and MgCO₃ deposit. Two commercial available austenitic stainless steel grade of AISI 304 and AISI 316L were selected. Austenitic stainless steel type AISI 304 and 316L are extensively and widely used in petrochemical, thermal power plants, boiler part, pressure vessel, etc. due to their improved corrosion resistance at elevated temperatures and corrosive conditions. The corrosion behaviour and morphological developments were investigated by weight change kinetics, morphological structures of deposits on the surface of alloy scales by scanning electron microscopy (SEM), elemental composition of oxide alloy was analyzed by energy dispersive X-Ray (EDS) analysis and the corrosion product was analyzed by X-ray diffraction. The oxidation kinetics curves of the alloy showing parabolic nature for both alloys. CaCO₃ coated AISI 304 revealed weight loss at all temperature while AISI 316L reveals weight gain at 850°C and 900°C. However at 950°C and 1000°C AISI 316L suffered weight loss through out the experiment period. Meanwhile MgCO₃ induced alloy AISI 304 suffered the weight gain at 850°C and weight loss at 900°C, 950°C and 1000°C as similar with AISI 316L. On the other hand, AISI 316L showed the highest corrosion resistance than AISI 304 because of the weight loss was relatively small than AISI 304 at 120hr. By increasing the temperature and exposure time the weight loss of alloys were increased. The developments of adherent, compact with pores and crack scale on the AISI 304 and 316L were due to evolution of CO and CO₂ gas. Fe₂O₃ , Cr₂O₃ and CaFeO₂ are corrosion products formed on the AISI 304 and 316L coating with CaCO₃. For MgCO₃ coated alloy, the corrosion product are Fe₂O₃ , Cr₂O₃ , MgFe₂O₂ and MgCrO₄ The hot corrosion morphology of the alloy induced by CaCO₃ coating shows a typical uniform attack, some pores and crack developed while on the MgCO₃ coated alloy shows some intergranular attack with crack and pores.
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  • Publication
    The effect of HAP addition on properties F-75 alloy fabricated via P/M 6 for biomaterial applications
    ( 2010)
    Rohaya Abdul Malek
    A Co-Cr-Mo (ASTM F-75) alloy is generally used because of their mechanical properties, good wear and corrosion resistance as well as biocompatibility. In order to obtain chemical similarity and interfacial bond form between implanted biomaterials and living tissue, addition of Hydroxyapatite (HAP) is required. This study has focused on a research on F-75 alloy mixed with HAP fabricated by powder metallurgy (P/M) technique. The effect of HAP addition ranging between 2 and 10 wt.% on biocompatibility, physical and mechanical properties were examined. During compaction, 500MPa of pressure was applied using uniaxial press machine. The samples were sintered into tube furnace at 1100˚C in argon atmosphere. The samples with dimensions of approximately 5mm in thickness and 19mm in diameter were produced. To analyse the result, the reference sample (F-75 alloy without HAP powder) and composites were compared. All the samples were tested to determine shrinkage, grain size, bulk density, apparent porosity, microhardness and corrosion test. For biocompatibility (corrosion test), all samples were immersed into simulated body fluid of 0.9% sodium chloride solution at 37˚C in 6-week duration. Every interval of 48 hours, the weight loss per area was recorded. By increasing amount of HAP, it is noticed that the composites were less shrink and grain size getting larger compared to the reference sample. The largest grain size was obtained for composite consists of 10 wt.% of HAP (32.56μm) meanwhile the smallest grain size was obtained for reference sample (21.43μm). These results are inversely proportional to the decreasing value of bulk density and microhardness. The result of apparent porosity closely to 30% is obtained due to the increasing amount of HAP. Higher result of apparent porosity is required for bone ingrowth purposes. For microstructure analysis, the composites microstructure showed agglomeration of HAP and pores scattered on the composite surface. Meanwhile, biocompatibility test has indicated that the corrosion rate are increasing due to addition of HAP except for composite that consists of 2 wt.% of HAP which has the lowest corrosion rate among others (2.53mpy). The possibilities that contribute to the increasing of corrosion rate as a function of HAP addition are; the formation of general attack and pitting between matrix and electrochemical solution used. Besides, the formation of apatite layer can be clearly seen on the composite surface as predicted. According to the results, composite contains 6 wt.% of HAP shows an interesting result for apparent porosity and corrosion resistance that can be correlated to the requirement of biomaterial applications.
  • 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
    Optimization of phosphate, nitrate, sucrose and incubation time on the production of ascorbic acid in suspended callus of Citrus Grandis (L.) Osbeck
    ( 2010)
    Nor Alina Nazri
    The potential of C. grandis tissue in producing high amount of ascorbic acid has been investigated in this study. In tissue culture technique, nutrients in the media have been a major factor in manipulating the final yield required. Phosphate, nitrate and sucrose with incubation time have been studied on their influence in production of ascorbic acid in C. grandis suspension cultures. The result obtained in factorial design indicates that among all four factors, only sucrose and incubation time give significant effect when present alone. However, all four factors have influence in the production when present together. This result was verified by the significant interaction among all the four factors. Then, suitable ranges of concentration for selected factors that obtained from factorial design were used in the optimization study. By using response surface methodology (RSM) through central composite design (CCD), the optimum conditions of selected factors were obtained. The result shows that when callus was supplied with 506.3mg/l phosphate, 1916.7 mg/l nitrate and 65.2 g/l sucrose and incubated in dark room for 7 days, maximum production of ascorbic acid at 34.53 ± 2.20 mg/l was obtained. The results obtained were in the range of predicted ascorbic acid and therefore the model of the study is acceptable. Then, the cultivation of callus in a bioreactor was carried out. The concentration of ascorbic acid obtained was 9 mg/l of which is very low compared to the production obtained in flask. This is due to the restriction provided by the unsuitable condition in the bioreactor for the growth of callus.
  • Publication
    Mechanical and thermal properties of chitosan filled recycled polyethylene biocomposites
    ( 2010)
    Azieyanti Nurain Azmin
    The research was focused to investigate the utilization of chitosan biopolymer on properties of recycled polyethylene (RPE). The effect of chitosan loading of RPE biocomposites on mechanical properties, thermal properties, water absorption and morphology were studied. Chitosan was compounded with RPE using Z-blade mixer at processing temperature 180°C and rotor speed 50 rpm. The results show that the increasing chitosan loading increased the tensile strength, Young’s modulus and water absorption but decreased the elongation at break of RPE/chitosan biocomposites. The morphology study show the higher filler loading exhibit better dispersion of chitosan in matrix. The crystallinity of the biocomposites increased with increasing chitosan loading. The presence of α-methacryloxypropyltrimethoxysilane (Silane A-174) have increase the tensile strength, Young’s modulus, crystallinity and decreased the elongation at break and water absorption of RPE/chitosan biocomposites. The SEM micrograph show the better interfacial interaction between chitosan and RPE. The effect maleic anhydride-grafted-polyethylene (MAPE) as compatibilizer improved the tensile strength and Young’s modulus but elongation at break and water absorption decrease. The compatibilized biocomposites indicates higher crystallinity and enhanced the adhesion of filler and matrix. The biocomposites with MAPE and silane show higher tensile strength, Young’s modulus and crystallinity compared to the biocomposites without MAPE and silane, whereas lower elongation at break and water absorption. The improvement of tensile properties was supported by morphology studied. The addition of commercialized eco-degradant PD 04 as additive in RPE/chitosan biocomposites was increased the tensile strength, Young’s modulus and reduced the elongation at break.
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