Mohd Firdaus Omar
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Preferred name
Mohd Firdaus Omar
Official Name
Mohd Firdaus, Omar
Alternative Name
Omar, Mohd Firdaus
Mohd, Firdaus Omar
Omar, M. F.
Omar, Mohdfirdaus
Omar, Mohd F.
Main Affiliation
Scopus Author ID
36149536300
Researcher ID
U-8459-2019

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  • Publication
    Effect of Nitrate Acid Treated Dolomite on the Tensile Properties of Ultra-High Molecular Weight Polyethylene (UHMWPE) Composites
    ( 2024-01-01)
    Abdullah S.F.A.
    ;
    Saleh S.S.M.
    ;
    Nur Farahiyah Mohammad
    ;
    Syarifah Nuraqmar Syed Mahamud
    ;
    Mohd Firdaus Omar
    ;
    Akil H.M.D.
    ;
    Chang B.P.
    ;
    Saliu H.R.
    ;
    Rostam N.H.
    ;
    Gondro J.
    Ultra-High Molecular Weight Polyethylene (UHMWPE) polymers have been used in biomedical applications due to its biocompatibility, durability, toughness and high wear resistance. To enhance the mechanical properties, various types of minerals are commonly utilized as fillers in UHMWPE. One of the minerals is dolomite, which has been recognized as a valuable mineral with versatile applications, particularly in the field of biomedical applications. This paper presents the tensile properties of UHMWPE composites that filled with dolomite and treated-dolomite at various filler loading (i.e., 1-5 wt.%). Nitric acid and diammonium phosphate were used to treat the dolomite. From the results, the peaks of the FTIR spectrum displays carbonate (CO3–2), phosphate (PO4–3) and hydroxyl (OH–) groups in the ct-dolomite powder sample while the XRD pattern reveals that using dolomite treated with 1M nitric acid resulted in the presence of calcium hydroxide phosphate (Ca10(PO4)5(OH)) and MgO. For tensile strength, UHMWPE/ct-dolomite composites show better tensile strength than the pure UHMWPE composites. Treated improve the dolomite filler and resulted in significantly better matrix-filler interfacial interactions and improve the properties.
  • Publication
    Studies on factors affecting unconfined compressive strength of industrial rubber sludge containing heavy metals treated using ordinary Portland cement via stabilization/solidification technique
    ( 2020-12-18)
    Abdul Latif Abdul Rani
    ;
    Rashid N.A.
    ;
    Muhd Afiq Hizami Abdullah
    ;
    Mohd Firdaus Omar
    ;
    Salim A.S.
    ;
    Anuar N.A.I.
    High concentration of selected heavy metals within industrial rubber sludge collected from rubber industry wastewater treatment plant has classified the waste as scheduled waste. Special treatment to the waste by using ordinary Portland cement via solidification/stabilization (S/S) technique has been performed in laboratory scale. The objective of this research is to determine related factors that affect unconfined compressive strength (UCS) performance of stabilised/solidified (s/s) cube specimens which contains industrial rubber sludge waste. Other parameters observed include the curing condition (i.e. air and water immersion curing method), waste composition, specimen age and density. The prepared fresh mix were cast in plastic moulds in order to produce 50 mm3 cubical shape specimens and leaved to set approximately 24 to 48 hours. The prepared specimen batches are S1 (90% OPC + 10% waste), S2 (70% OPC + 30% waste), S3 (50% OPC + 50% waste). UCS was performed on respective specimen age of 7 and 28 days. Positive results were obtained as relatively the average compressive strength of 7 day air cured specimens reach 5.25 MPa, 5.28 MPa, and 2.16 MPa for S1, S2 and S3.While, 28 days air cured specimens results are 9.59 MPa, 8.01 MPa, and 1.46 MPa for S1, S2, and S3 respectively. As for water immersion, the compressive strengths are 8.19 MPa, 4.93 MPa, and 1.90 MPa for 7 days, and 7.75 MPa, 10.10 MPa, and 2.11 MPa for 28 days at respective S1, S2 and S3 sequence. As conclusion, the specimens prepared passed the minimum requirement for secured landfill disposal which is at 1 MPa.
  • Publication
    Evaluation on physical and chemical properties of treated industrial wastewater sludge containing latex and heavy metals using ordinary Portland cement via stabilization / solidification technique
    ( 2020-07-09)
    Abdul Latif Abdul Rani
    ;
    Rashid N.A.
    ;
    Muhd Afiq Hizami Abdullah
    ;
    Mohd Firdaus Omar
    Industrial wastewater sludge containing latex collected from rubber industry wastewater treatment plant has classified the waste as scheduled waste due to high concentration of selected heavy metals within it. Laboratory scale of special treatment via solidification/stabilization (S/S) technique has been performed to the waste by using ordinary Portland cement. The objective of this research is to evaluate the chemical properties of the raw waste using X-Ray Fluorescence (XRF) and physical properties related to unconfined compressive strength (UCS) performance of stabilised/solidified (s/s) cube specimens. Other factors took into consideration include the curing condition using air and water immersion curing technique, waste addition percentage, specimen age and density. The fresh mix prepared were cast in plastic moulds internal dimension of 50 mm3 producing cubical shape specimens and cured approximately 24 to 48 hours. The prepared specimen batches are A1 (90% OPC + 10% waste), A2 (70% OPC + 30% waste), A3 (50% OPC + 50% waste). Chemical analyses using XRF indicates that raw sludge contains approximately several heavy metals such as Aluminium (30%), Phosphorus, P (17.5%) and Zinc, Zn (11.7%). UCS testing were conducted on 7 and 28 days of specimen age. Positive average compressive strength results of 7 day air cured specimens reach 5.25 MPa, 5.28 MPa, and 2.16 MPa for A1, A2 and A3. Next, 28 days air cured specimens results are 9.59 MPa, 8.01 MPa, and 1.46 MPa for A1, A2, and A3 respectively. As for water immersion, the compressive strengths are 8.19 MPa, 4.93 MPa, and 1.90 MPa for 7 days, and 7.75 MPa, 10.10 MPa, and 2.11 MPa for 28 days at respective A1, A2 and A3 sequence. Based on the UCS performance, the tested specimens surpassed the minimum requirement for secured landfill disposal which is at 1 MPa.
  • Publication
    A Comparison Process Between Wet Lay-Up, Single Vacuum Bagging and Double Vacuum Bagging Toward Natural Fibre (Palm, Coconut and Kenaf) Reinforced Epoxy Composite Laminates
    ( 2023-06-01)
    Zakaria M.R.
    ;
    Ahmad Thirmizir M.Z.
    ;
    Zainol Abidin M.S.
    ;
    Md Akil H.
    ;
    Mohd Firdaus Omar
    ;
    Anjang Ab Rahman A.
    ;
    Nosbi N.
    ;
    Ab Ghafar N.
    The mechanical properties of palm, coconut, and kenaf fibre-reinforced epoxy composite laminates were evaluated using tensile (ASTM D3039) and flexural (ASTM D790) tests. The laminates were fabricated using different methods such as double vacuum bagging, single vacuum bagging, and wet lay-up. Results indicate that double vacuum bagging produced superior mechanical properties (up to 54.12% higher flexural modulus) compared to single vacuum bagging and wet lay-up methods. SEM images showed complete impregnation of fibres and a good interface between fibre and matrix in the composites produced via the double vacuum bagging method. This process creates a denser sample and allows the resin to penetrate the plies and core, eliminating voids in the laminate structure. Additionally, kenaf fibre-reinforced epoxy composite laminates exhibited higher mechanical properties (up to 104.82% higher tensile strength) compared to palm and coconut fibre-reinforced epoxy composite laminates.
      1
  • Publication
    Room Temperature Synthesis and Characterization of HKUST-1, Metal–Organic Frameworks (MOFs)
    ( 2023-01-01)
    Ahmad S.
    ;
    Mohd Firdaus Omar
    ;
    Mahdi E.M.
    ;
    Khairul Anwar Abdul Halim
    ;
    Shayfull Zamree Abd. Rahim
    ;
    Sam Sung Ting
    ;
    Md. Akil H.
    ;
    Nosbi N.
    In the present work, HKUST-1 has been synthesized at room temperature with 1:0, 1:1, and 0:1 ratio of ethanol and water. A wide range of reaction conditions were explored in order to understand the effects of solvent and temperature. It was discovered that various precursors yielded products with various BET specific surface areas. The effect of water may therefore be explained by the decrease in reaction rate with an increasing concentration of reactants. The XRD data and SEM analysis showed that both MOFs were very crystalline in the product.
      1
  • Publication
    Influence of filler surface modification on static and dynamic mechanical responses of rice husk reinforced linear low-density polyethylene composites
    ( 2022-01-01)
    Mohd Firdaus Omar
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Sam Sung Ting
    ;
    Jez B.
    ;
    Nabialek M.
    ;
    Akil H.M.
    ;
    Nik Noriman Zulkepli
    ;
    Shayfull Zamree Abd. Rahim
    ;
    Azmi A.
    Filler surface modification has become an essential approach to improve the compatibility problem between natural fillers and polymer matrices. However, there is limited work that concerns on this particular effect under dynamic loading conditions. Therefore, in this study, both untreated and treated low linear density polyethylene/rice husk composites were tested under static (0.001 s-1, 0.01 s-1and 0.1 s-1) and dynamic loading rates (650 s-1, 900 s-1and 1100 s-1) using universal testing machine and split Hopkinson pressure bar equipment, respectively. Rice husk filler was modified using silane coupling agents at four different concentrations (1, 3, 5 and 7% weight percentage of silane) at room temperature. This surface modification was experimentally proven by Fourier transform infrared and Field emission scanning electron microscopy. Results show that strength properties, stiffness properties and yield behaviour of treated composites were higher than untreated composites. Among the treated composites, the 5% silane weight percentage composite shows the optimum mechanical properties. Besides, the rate of sensitivity of both untreated and treated composites also shows great dependency on strain rate sensitivity with increasing strain rate. On the other hand, the thermal activation volume shows contrary trend. For fracture surface analysis, the results show that the treated LLDPE/RH composites experienced less permanent deformation as compared to untreated LLDPE/RH composites. Besides, at dynamic loading, the fracture surface analysis of the treated composites showed good attachment between RH and LLDPE.
      1
  • Publication
    Comparative study on the properties of cross-linked cellulose nanocrystals/chitosan film composites with conventional heating and microwave curing
    ( 2020-12-20)
    Gan P.G.
    ;
    Sam Sung Ting
    ;
    Muhammad Faiq Abdullah
    ;
    Mohd Firdaus Omar
    ;
    Tan W.K.
    Cross-linking of chitosan film composites was carried out by using conventional heating and microwave curing methods in this study. Non-cross-linked and glutaraldehyde (GA) cross-linked neat chitosan and cellulose nanocrystals (CNC)/chitosan film composites were cured by either conventional oven heating or microwave irradiation. Tensile strength and Young's modulus of chitosan composites were enhanced significantly by the addition of CNC and GA especially for the microwave-cured samples. The changes in chemical interaction of the chitosan film composites was determined by Fourier transform infrared (FTIR) spectroscopy. The microwave-cured GA-cross-linked chitosan film composites were more thermally stable than non-cross-linked and conventionally heated GA-cross-linked chitosan film composites due to the formation of a more stable structure between GA and chitosan. Nevertheless, the reduced antimicrobial efficacy of film composites against Escherichia coli, Bacillus subtilis, and Saccharomyces cerevisiae was observed in cross-linked film composites compared with non-cross-linked composites.
      1
  • Publication
    Effect of glutaraldehyde as crosslinker on the properties of cellulose nanocrystal/chitosan films
    ( 2020-11-24)
    Gan P.G.
    ;
    Sam S.T.
    ;
    Mohd Firdaus Omar
    ;
    Muhammad Faiq Abdullah
    Cellulose nanocrystals (CNC) were isolated from the empty fruit bunch as the reinforcing filler to enhance the tensile and thermal properties of chitosan films. The addition of CNC has greatly increased the tensile strength of the chitosan films from 32.9 MPa for neat chitosan film to 50.9 MPa for 5 wt% CNC/chitosan films. The addition of glutaraldehyde as crosslinker has further improved the tensile property of chitosan films. However, the incorporation of CNC and glutaraldehyde has a negative effect on the elongation at break of the films due to restricted polymer chain mobility. Besides, the addition of CNC also enhanced the melting temperature of the chitosan films. The crosslinking process has further increased the melting temperature to 112.8 C with the addition of 5 wt% CNC. Therefore, the crosslinked CNC/chitosan films display greater property reinforcements than non-crosslinked films.
      1
  • Publication
    Optimization of injection moulding process via Design of Experiment (DOE) method based on Rice Husk (RH) reinforced Low Density Polyethylene (LDPE) composite properties
    ( 2022-01-01)
    Haliza Jaya
    ;
    Nik Noriman Zulkepli
    ;
    Mohd Firdaus Omar
    ;
    Shayfull Zamree Abd. Rahim
    ;
    Nabiałek M.
    ;
    Jez K.
    ;
    Mohd. Mustafa Al Bakri Abdullah
    Optimal parameters setting of injection moulding (IM) machine critically effects productivity, quality, and cost production of end products in manufacturing industries. Previously, trial and error method were the most common method for the production engineers to meet the optimal process injection moulding parameter setting. Inappropriate injection moulding machine parameter settings can lead to poor production and quality of a product. Therefore, this study was purposefully carried out to overcome those uncertainty. This paper presents a statistical technique on the optimization of injection moulding process parameters through central composite design (CCD). In this study, an understanding of the injection moulding process and consequently its optimization is carried out by CCD based on three parameters (melt temperature, packing pressure, and cooling time) which influence the shrinkage and tensile strength of rice husk (RH) reinforced low density polyethylene (LDPE) composites. Statistical results and analysis are used to provide better interpretation of the experiment. The models are form from analysis of variance (ANOVA) method and the model passed the tests for normality and independence assumptions.
      1
  • Publication
    Network Structure and Mechanical Properties of Flexible Electronic Interconnects based on Linear Low-Density Polyethylene (LLDPE) and Liquid Silicone Rubber (LSR) Conductive Polymer Composites
    ( 2024-03-01)
    Khairul Anwar Abdul Halim
    ;
    Mohd Arif Anuar Mohd Salleh
    ;
    Badrul F.
    ;
    Azlin Fazlina Osman
    ;
    Mohd Firdaus Omar
    ;
    Suhaimi A.S.
    ;
    Muhammad Salihin Zakaria
    Conductive polymer composites (CPCs) with the ability to maintain high conductivity whilst remaining flexible at various operating temperatures and conditions have gained interest as potential materials for electronic interconnect applications. The ability of a polymer matrix to conduct electricity is mainly dependent on the conductive filler loadings as well as the formation of network paths within the CPCs. The main aim of this research work was to establish and understand the correlation between the network structure formation and mechanical properties of linear low-density polyethylene/copper (LLDPE/Cu) and liquid silicone rubber/copper (LSR/Cu) CPCs. Various techniques such as electron microscopy, thermal studies, four-point probe, and tensile testing were employed in this study. Furthermore, selected samples were characterized and tested using synchrotron micro-x-ray fluorescence (XRF) technique and dynamic mechanical analysis (DMA). It was found that the electrical conductivity of the CPCs increased with increasing filler loadings. Addition of Cu filler had a marginal effect on the tensile strength of both LLDPE/Cu and LSR/Cu CPCs. Nevertheless, it was found that the elongation at break for LLDPE/Cu consistently increased with the addition of Cu whereas, for LSR/Cu samples, the elongation at break decreased with the addition of Cu at various loadings. The scanning electron microscopy (SEM) micrographs obtained show that the particles of Cu were closer to one another at higher filler loadings. The data obtained revealed the potential for utilizing CPCs as flexible interconnects suitable for advanced electronic applications.
      1