Coir ( Cocos nucifera ), a ligno-cellulosic fiber, is cheap and abundant in the coastal regions of tropical countries. In this paper the effect of physical and chemical treatments on the mechanical properties of coir fibers is reported. Changes in moisture regain, crystallite orientation, and percentage crystallinity were observed when fibers were treated with hydrochloric acid (10%), sodium hydroxide (10%), and acetic acid (10%). Scanning electron micrographs of the fractured surfaces of the fibers showed extensive fibrillation. Tenacity and elongation-at-break decreased with chemical treatment and UV irradiation. An increase in initial modulus and crystallinity was observed with alkali treatment.

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Hybrid laminates consisting of glass fiber mat, chopped bristle coir fibers and un saturated polyester resin matrix were fabricated. Effect of treatment of coir fibers with alkali and dichloro methyl vinyl silane on the mechanical properties of the laminates was investigated. The hybrid composites having 66% resin (w/w) and 19.7% chopped coir fiber (1cm long) showed 35% improvement in flexural strength and 70% in flexural modulus over the neat polyester resin sheets. Mechanical properties of laminates increased on increasing the coir fiber length up to 1 cm beyond which a decrease in strength was observed. Hybrid laminates fabricated from NaOH treated coir fibers had better mechanical properties than those fabricated from untreated coir fibers. A decrease in thermal conductivity was observed with increasing weight fraction of coir fibers.

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activation energy for viscous flow which in the present case can be calculated by the technique of Saini and Shenoy (1984) and is found to be equal to 8 kcal/mol.(4) The plots of 11 vs. .i. and Nl vs q2 under the required conditions can now be readily obtained by substituting the correct value of MFI in the unified curves or in eq 5 and 7.In the case of the solid-state deformation behavior, the necessary data can be regenerated from Figure 9 at any temperature of interest merely by determining the comparative stress value after 24 h of deformation. The value thus obtained as uo can be used in Figure 9 to generate the necessary expected long-term behavior of the PVDF product. The method of coalescence as demonstrated here should, in principle, be applicable to all creep experiments and help greatly in curtailing experimentation time. ConclusionThe present work demonstrates a very effective method for coalescing available data in the melt and solid state deformation behavior of PVDF. The resulting master curves are grade and temperature invarient in the case of the melt data and at least temperature invarient in the case of the solid-state data. The benefits of such master curves are that experimentation is simplified and the time required for experimentation curtailed. The unified curves, therefore, can act as hand tools for quick estimates of deformation behavior of PVDF necessary for design purposes.Nomenclature C, constant in eq 9 E activation energy for viscous flow, kcal (mol K) F force due to test load, dyne L test load, kg L , load at condition 1, kg L2 load at condition 2, kg LN nozzle length, cm m adjustable material parameter in eq 11, dimensionless n power law index in eq 13, dimensionless N model parameter in eq 7, dimensionless N , primar normal stress difference as defined in eq 10, Q flow rate, cm3/s R gas constant, kcal/mol RN nozzle radius, cm R, piston radius, cm t time scale, h T1 temperature at condition 1, K T2 temperature at condition 2, K Greek letters 4 shear rate, s-l p density, g/cm3 T~ zero shear viscosity, poise q apparent shear viscosity, poise X relaxation time, s go stress at the end of 24 h, d n/cm2 T shear stress, dyn/cm2 dyn/cm P g comparative stress, dyn/cm f primary normal stress difference coefficient, dyn d / c m z Registry No. PVDF, 24937-79-9. Literature Cited Carreau, P. J. Trans. SOC. Rheol. 1972, 16, 99. Gebauer, P. DynamA Nobel AG, 0-5210, Troisdorf, FRG, private communicaPugiia, L. Pennwait Corp., Philadelphia, PA 19102, private communication, Saini, D. R.; Shenoy, A. V. J . Mecromol. Sci., Phys. 1984, 822, 437. Shenoy, A. V.; Saini, D. R.; Nadkarni, V. M. J . Appl. Polym. Sci. 1982, 27, Shenoy, A. V.; Saini, D. R.; Nadkarni, V. M. Rheol. Acta 1883, 22, 209. Shenoy, A. V.; Saini, D. R. Rheol. Acta 1984a, 23, 368. Shenoy, A. V.; Saini, D. R. Chem. Eng. Commun. 1984b, 27, 1. Wagner, M. H. Rheol. Acta 1976, 15, 136. Wagner, M. H. Rheol. Acta 1977, 16, 43. tion, 1985.1985. 4399. This paper describes the treatment of bristle coir fibers with a dilute solution of unsaturate...