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Abstracts (International Journals and Books)

[60] Sudarisman and I. J. Davies, “Influence of compressive pressure, vacuum pressure, and holding temperature applied during autoclave curing on the microstructure of unidirectional CFRP composites”, Adv. Maters. Res., 41-42 pp. 323-328 (2008).

Abstract: The microstructure (i.e., fibre volume fraction, void content, and fibre misalignment) of unidirectional carbon fibre-reinforced polymer (CFRP) composites was optimised by controlling several parameters during manufacture, namely: (i) compressive pressure (0.25~1.25 MPa, in steps of 0.25 MPa), (ii) vacuum pressure (−0.15, −0.20, −0.30, −0.45, and −0.65 MPa), and (iii) holding temperature (100~140 ^oC, in steps of 10 ^oC), applied during autoclave curing with the holding time being 30 minutes for all specimens. Optical micrographs captured from cross-sectional, through-the thickness areas, and in-plane areas of the resulting composites were evaluated and analysed in order to describe their microstructural characteristics.

[59]   Sudarisman and I. J. Davies, “Flexural failure of unidirectional hybrid fibre–reinforced polymer (FRP) composites containing different grades of glass fibre”, Adv. Maters. Res., 41-42 pp. 357-362 (2008).

Abstract: The flexural behaviour of 6-ply unidirectional hybrid fibre-reinforced polymer (FRP) matrix composites containing a mixture of E-glass and S2-glass fibres was investigated. A high performance epoxy system comprising of Kinetix^® R240 epoxy resin (combined with Kinetix^® H160 epoxy hardener) was utilised for the composite matrix. Flexural testing was conducted in accordance with Procedure A of the ASTM D790-03 test standard on a universal testing machine equipped with a three-point bend test rig. In addition to varying the stacking configurations of the composite prepregs, the influence of span-to-depth ratio on the flexural properties and failure mechanisms was also studied. The failure mechanisms of the resulting fractured specimens were characterised using optical microscopy and compared with those noted by the authors in previous work.

[58]  Sudarisman and I. J. Davies, "The effect of processing parameters on the flexural properties of unidirectional carbon fibre-reinforced polymer (CFRP) composites", Maters. Sci. Eng. Part A, in press (2008).

Abstract: The flexural properties (e.g., strength, elastic modulus) of unidirectional carbon fibre-reinforced polymer (CFRP) composite were optimised by controlling the processing parameters during manufacture, namely: (i) the concentration of epoxy (45~65 wt%) within an acetone solution for wetting the carbon fibres, (ii) the compressive pressure (0.25~1.25 MPa), and (iii) the holding time (20~40 minutes) applied during vacuum autoclave curing at 120 ^oC. Flexural properties of the resulting composites were evaluated using the 3-point bend configuration in accordance with the ASTM D790-03 standard. It was concluded that the optimum flexural properties (e.g., 1292 MPa flexural strength) were achieved using a 50 wt% epoxy solution, 1.0 MPa compressive pressure, and 30 minutes holding time during vacuum autoclave curing.

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[57]   Sudarisman, I. J. Davies, and H. Hamada, "Compressive failure of unidirectional hybrid fibre-reinforced epoxy composites containing carbon and silicon carbide fibres", Compos. Part A, 38(3) pp. 1070-1074 (2007).

Abstract: The compressive failure of unidirectional hybrid fibre-reinforced epoxy matrix composites containing carbon (C) and silicon carbide (SiC) fibres has been investigated. In contrast to the case of flexural testing previously investigated by the authors (abstract and paper), no significant increase in compressive strength, elastic modulus, or work of fracture was noted for the case of composites containing a mixture of C and SiC fibres. The specific compressive strength and elastic modulus generally decreased with increasing SiC fibre content due to the higher density of these fibres. Failure modes of tested specimens were classified into two main groups, namely compressive shear and compressive crushing, with the presence of fibre kinking and longitudinal splitting being noted in both cases.

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[56]   K. Itatani, T. Umeda, Y. Musha, and I. J. Davies, “Microstructure of spherical calcium-phosphate agglomerates prepared by spray-pyrolysis and freeze-drying techniques”, Phosphorous Res. Bull., 20 pp. 47-60 (2006).

Abstract: Microstructural changes taking place during the heating of spherical calcium-phosphate (Ca₁₀(PO₄)₆(OH)₂ (HAp) and b-Ca₃(PO₄)₂) agglomerates prepared by spray-pyrolysis and freeze-drying techniques have been reviewed. The powders are prepared (1) by the spray-pyrolysis of calcium phosphate (Ca/P ratio=1.50 and 1.67) solution containing Ca(NO₃)₂, (NH₄)₂HPO₄ and concentrated HNO₃ at 600°C, and (2) by the flash freezing of droplets (Ca(CH₃COO)₂, PO(OCH₃)₃ and concentrated HNO₃) in a cryogen, subliming of water ice under reduced pressures, and finally heat-treating of freeze-dried powder at 900°C for 1 h. In both techniques the resulting powders are composed of spherical agglomerates, reflecting the outward form of the starting droplets. The spray-pyrolyzed and heat-treated powder is generally composed of hollow spherical agglomerates, except for the case of ultrasonic spraying of droplets from 0.5 mol∙dm^-3 Ca(NO₃)₂/0.3 mol∙dm^-3 (NH₄)₂HPO₄ or higher concentration where dense spherical agglomerates are produced. The freeze-dried β-Ca₃(PO₄)₂ and HAp powders are prepared from solutions with Ca/P ratios of 1.44 and 1.67, respectively, and comprise of agglomerates with weakly-bonded particles..

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