Now showing 1 - 5 of 5
  • Publication
    Tool wear and surface evaluation in drilling fly ash geopolymer using HSS, HSS-Co, and HSS-TiN cutting tools
    ( 2021-04-01)
    Ghazali M.F.
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    Rahim S.Z.A.
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    Gondro J.
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    Pietrusiewicz P.
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    Garus S.
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    Stachowiak T.
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    Sandu A.V.
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    Korkmaz M.E.
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    Osman M.S.
    This paper reports on the potential use of geopolymer in the drilling process, with respect to tool wear and surface roughness. The objectives of this research are to analyze the tool life of three different economy-grade drill bit uncoated; high-speed steel (HSS), HSS coated with TiN (HSS-TiN), and HSS-cobalt (HSS-Co) in the drilling of geopolymer and to investigate the effect of spindle speed towards the tool life and surface roughness. It was found that, based on the range of parameters set in this experiment, the spindle speed is directly proportional to the tool wear and inversely proportional to surface roughness. It was also observed that HSS-Co produced the lowest value of surface roughness compared to HSS-TiN and uncoated HSS and therefore is the most favorable tool to be used for drilling the material. For HSS, HSS coated with TiN, and HSS-Co, only the drilling with the spindle speed of 100 rpm was able to drill 15 holes without surpassing the maximum tool wear of 0.10 mm. HSS-Co exhibits the greatest tool life by showing the lowest value of flank wear and produce a better surface finish to the sample by a low value of surface roughness value (Ra). This finding explains that geopolymer is possible to be drilled, and therefore, ranges of cutting tools and parameters suggested can be a guideline for researchers and manufacturers to drill geopolymer for further applications.
  • Publication
    Impedimetric transduction from a single-step thin film nanoporous aluminum oxide as a DNA sensing electrode
    ( 2024-02-01)
    Shamsuddin S.A.
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    Jasni I.
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    Ibau C.
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    A two-step anodization process has been widely used to grow a perfectly arranged Anodic Aluminum Oxide (AAO) nanoporous with high regularity and circularity. However, this method requires more time and electricity cost since the second step anodization will be conducted more than a couple of hours up to 24 h to obtain a perfect hexagonally arranged AAO. Besides, the usage of toxic chromic acid to remove the rough surface after the first anodization is not recommended. To solve this issue, a single-step of anodization method to grow AAO at 15 °C in 0.3 M of oxalic acid at 40 V for 1 h has been proposed. In this study, the growth AAO thin film will be tested as a DNA biosensor electrode. Prior to that, instead of using toxic chemicals, couple of drops of phosphoric acid solutions were used to treat the rough, uneven surfaces by promoting hydroxyl groups while at the same time widening and revealed the underneath pores. The AAO thin film is ready for the next step of surface modification without a second anodization step. Surface chemical functionalization using 3-aminopropyl-triethoxysilane (APTES) and glutaraldehyde is performed to immobilize the aminated-ssDNA probe on the surface. The electrochemical impedance technique is employed to monitor the changes in each layer of surface modifications. The charged transfer resistance (Rct) values are linearly increased with each new additional layer on the AAO surfaces during each step of surface modification and with the increase in ssDNA complementary target concentrations (10 fM-10 μM). From the performance test, the single-step AAO thin film electrode has shown great results in functioning as a DNA biosensor through a selectivity test. It has the capability to differentiate the complementary sequences from the single mismatched target with 3-fold.
  • Publication
    Structural, morphological and thermal properties of cellulose nanofibers from napier fiber (Pennisetum purpureum)
    ( 2020-09-01)
    Radakisnin R.
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    Jawaid M.
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    Sultan M.T.H.
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    The purpose of the study is to investigate the utilisation of Napier fiber (Pennisetum purpureum) as a source for the fabrication of cellulose nanofibers (CNF). In this study, cellulose nanofibers (CNF) from Napier fiber were isolated via ball-milling assisted by acid hydrolysis. Acid hydrolysis with different molarities (1.0, 3.8 and 5.6 M) was performed efficiently facilitate cellulose fiber size reduction. The resulting CNFs were characterised through Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), particle size analyser (PSA), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The FTIR results demonstrated that there were no obvious changes observed between the spectra of the CNFs with different molarities of acid hydrolysis. With 5.6 M acid hydrolysis, the XRD analysis displayed the highest degree of CNF crystallinity at 70.67%. In a thermal analysis by TGA and DTG, cellulose nanofiber with 5.6 M acid hydrolysis tended to produce cellulose nanofibers with higher thermal stability. As evidenced by the structural morphologies, a fibrous network nanostructure was obtained under TEM and AFM analysis, while a compact structure was observed under FESEM analysis. In conclusion, the isolated CNFs from Napier-derived cellulose are expected to yield potential to be used as a suitable source for nanocomposite production in various applications, including pharmaceutical, food packaging and biomedical fields.
  • Publication
    Structural and mechanical characterisation of cellulose nanofibers (CNF) from Pennisetum Purpureum reinforced with polylactic acid (PLA)
    This study aims to develop a composite scaffold based on polylactic acid reinforced with cellulose nanofibers from Pennisetum purpureum (PLA/CNF). The composite scaffolds were prepared via solvent casting and particulate leaching technique; sodium chloride (NaCl) was used as the porogen material. The influence of CNF on PLA is investigated; scaffolds were fabricated with different content of CNF (5%, 10% and 15%). The prepared composite scaffold was characterised using porosity measurements, Fourier-transform infrared spectroscopy (FTIR) and the compression strength and modulus were also evaluated in this study. The PLA/CNF scaffolds were highly porous with porosity higher than 80%. It was also shown that the porosity had a slight decrease with increasing CNF contents due to the compact arrangement of CNF within the scaffolds. Compression strength and modulus also show an increase in value as the CNF content increases. The results also show that introducing CNF to the PLA matrix can be considered beneficial for cartilage regeneration, cell attachment, and extracellular matrix (ECM) production.
  • Publication
    Physical, thermal, and mechanical properties of highly porous polylactic acid/cellulose nanofibre scaffolds prepared by salt leaching technique
    This study aimed to prepare and characterise polylactic acid (PLA) reinforced with cellulose nanofibre (CNF) from a Pennisetum purpureum-based composite scaffold and determine its structural and mechanical properties. Porous scaffolds with CNF compositions of 5‒20 wt% in the PLA matrix were developed using solvent casting and particulate leaching of its porogen at 90 wt% of loadings. Morphology studies using field emission scanning electron microscopy revealed that the scaffolds had well-interconnected pores with an average pore size range of 67‒137 μm and porosity >76%. X-ray diffraction confirmed the interconnectivity and homogeneity of the pores and the fibrous structure of the scaffolds. The compressive strength of the fabricated scaffolds varied between 2.34 and 6.66 MPa, while their compressive modulus was between 1.95 and 6.04 MPa for various CNF contents. Furthermore, water absorption and thermal degradation studies showed that the scaffold had good hydrophilicity and improved thermal stability. These findings highlight the need to modify the pore structure and mechanical performance simultaneously for tissue engineering. Thus, this study concludes that the developed PLA scaffolds reinforced with CNF from Pennisetum purpureum are potential candidates for cell attachment and extracellular matrix generation.