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Laser Flash Measurements on Thermal Conductivity of Bio-Fiber (Kenaf) Reinforced Composites

LEVI GARDNER, TROY MUNRO, EZEKIEL VILLARREAL, KURT HARRIS, THOMAS FRONK, HENG BAN

Abstract


Chemical treatment of natural fibers is a well-defined means of mechanical property improvement for use in natural fiber-reinforced composites. However, very little information is available illustrating the effect of such treatment on the thermal properties of such composites, particularly those reinforced with kenaf. Also, no study to date has reported the thermal conductivity of individual kenaf fibers. This presentation reports thermal transport in kenaf-epoxy composites and individual kenaf fibers. Unidirectionally oriented fiber-reinforced composites were fabricated using either untreated fibers or fibers treated in a 6% NaOH solution. Heat transfer in composite specimens was measured using the laser flash apparatus (LFA) method and differential scanning calorimetry (DSC) to respectively obtain effective thermal diffusivity and specific heat values. Scanning electron microscopy (SEM) images of treated fibers show much smoother outer surfaces with widespread fibril exposure relatively free of impurities compared to untreated counterparts. Cross sectional SEM images of kenaf-epoxy composites show an overall improvement in interfacial contact between technical fibers and matrix after chemical treatment. The effective thermal conductivities and thermal diffusivities of chemically treated fiber composites show a general increase over untreated fiber composites. This improvement is primarily attributed to improved interfacial contact between the fibers and epoxy matrix after chemical treatment. The thermal conductivity of individual fibers was evaluated using two techniques: the transient electro-thermal (TET) method and the relation k=Cp. Thermal conductivities of individual fibers showed no statistically significant change after chemical treatment. Any improvement in surface crystallinity after treatment does not appear to affect fiber thermal conductivity.


DOI
10.12783/tc33-te21/30336

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