Browsing by Author "Towo, Arnold N."

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    Fatigue Evaluation of Sisal Fibre - Thermosetting Resin Composites
    (2005) Towo, Arnold N.; Ansell, Martin P.
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    Fatigue of Sisal Fibre Reinforced Composites: Constant life Diagrams and Hysteresis Loop Capture
    (Composites Science and Technology, 2008) Towo, Arnold N.; Ansell, Martin P.
    Composite materials have been manufactured using untreated or 0.06 M NaOH treated sisal fibre bundles in a polyester or epoxy matrix. Mechanical tests have been conducted to establish the static properties of the composites which have been used to calculate the maximum loads used during fatigue testing. Composites containing alkali treated fibre bundles have better mechanical properties than those with untreated fibre bundles. Alkali treatment has the greatest effect for polyester resin matrices. S–N diagrams constructed from fatigue data at stress ratios of R = 0.1 (tension–tension) and R = −1 (reversed loading) show improvement in the fatigue lives of composites following alkali treatment of sisal fibre bundles. Constant-life diagrams for epoxy matrix composites with untreated or alkali treated fibre bundles show the superiority of the alkali treated fibre composites for low cycle fatigue. Composites loaded in tension–tension fatigue (R = 0.1) exhibit hysteresis loops with diminishing loop area with increasing number of cycles. The composites loaded in reversed loading fatigue (R = −1) generate loops with increasing loop area with increasing number of cycles. Failure modes in tension–tension and reversed loading are very different with a distinctive buckling failure mode at R = −1.
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    Shear Strength at Sisal Fibre-Polyester Resin Interfaces: Use of Inverse Gas Chromatography to Study Pre-Treatment Effects
    (Composite Interfaces, 2007) Price, G. J.; Pastor, Marie-Laetitia; Towo, Arnold N.; Ansell, Martin P.; Packham, David E.
    Inverse gas chromatography, IGC, has been used to investigate changes to the surface of Sisal fibres on treatment with sodium hydroxide. By determining the retention of a series of alkane probes and of probes with acidic or basic character, it was shown that little change to the chemical nature of the surface occurs as measured by the enthalpy of adsorption of alkane probes or the dispersion component of the surface free energy. This IGC study supports the conclusion of previous work involving S.E.M. which suggested that the major effect of the treatment was the removal of weak or adventitious layers from the substrate surface, thus increasing the interfacial shear strength when incorporated into polyester resin.
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