Temperature Dependence of the Dielectric Properties of Rubber Wood
Keywords:
Dielectric constant, dielectric loss factor, microwave frequency, temperature, polarization, activation energy, wood anisotropyAbstract
The effect of temperature on the dielectric properties of rubber wood were investigated in three anisotropic directions-longitudinal, radial, and tangential, and at different measurement frequencies. Low frequency measurements were conducted with a dielectric spectrometer, and high frequencies used microwave applied with open-ended coaxial probe sensors. Dielectric constants and dielectric loss factors were measured at temperatures from 25 to 100°C. A large dielectric dispersion occurred at frequencies less than 10 Hz and at temperatures more than 60°C. The minimum peak value of the dielectric loss factors shifted towards higher frequencies at higher temperatures in all three grain directions. The tangential direction showed the highest activation energy. The dielectric constant decreased as frequency increased from 1 to 10 GHz, and thereafter remained unchanged with additional frequency increases. The dielectric constant exhibited higher values at higher temperatures. The dielectric loss factor showed a peak value at around 10 GHz at 25°C.References
Athey, T. W., M. A. Stuchly, and S. S. Stuchly. 1982. Measurement of RF permitivity of biological tissues with an open-ended coaxial line. IEEE Trans. MTT.30: 82-86.nJames, W. L. 1968. Effect of temperature on readings of electric moisture meters. Forest Prod. J.18(10):23-31.nJames, W. L. 1975. Dielectric properties of wood and hardboard. Variation with temperature, frequency, moisture content, and grain direction. Res. Pap. FPL-245, USDA Forest service, Forest Prod. Lab., Madison, WI. 33 pp.nJames, W. L. 1977. Dielectric behavior of Douglas-fir at various combinations of temperature, frequency, and moisture content. Forest Prod. J.27(6):44-48.nJames, W. L., and D. W. Hamil. 1965. Dielectric properties of Douglas-fir measured at microwave frequencies. Forest Prod. J.15(2):51-56.nJonscher, A. K. 1983. Dielectric relaxation in solids. Chelsea Dielectric Press, London, UK.nKabir, M. F., W. M. Daud, H. A. A. Sidek, and K. Khalid. 1996. Dielectric behaviour of rubber wood. Bull Malaysian Solid State Sci. Technol.6(2):57-67.nKabir, M. F., W. M. Daud, H. A. A. Sidek, and K. Khalid. 2000. Equivalent circuit modeling of the dielectric properties of rubber wood at low frequency. Wood Fiber Sci.32(4):450-457.nKhalid, K., Z. Zakaria, and W. M. Daud. 1996. Variation of dielectric properties of oil palm mesocarp with moisture content and fruit maturity at microwave frequencies. Elaeis8(2):83-93.nKraszewski, A., M. A. Stuchly, and S. S. Stuchly. 1982. ANA calibration method for measurement of dielectric properties. IEEE Trans. IM.32(2):385-387.nMartin P., R. Collet, P. Barthelemy, and G. Roussy. 1987. Evaluation of wood characteristics: Internal scanning of the material by microwaves. Wood Sci. Technol.21:361-371.nNanassy, A. Z. 1964. Electric polarization measurement on yellow birch. Can. J. Physics42:1270-1281.nNanassy, A. Z. 1970. Overlapping of dielectric relaxation spectra in oven-dry yellow birch at temperature from 20 to 100°C. Wood Sci. Technol.4:104-121.nNorimoto, M., and T. Yamada. 1970. The dielectric properties of wood. IV. On the dielectric dispersion of oven-dried wood. Wood Res.50:36-49.nNorimoto, M., and T. Yamada. 1976. Dielectric properties of wood. Wood Res.59/60:106-152.nTinga, W. R. 1969. Dielectric properties of Douglas-fir at 2.45 GHz. J. Microwave Power4(3):162-164.nTsutsumi, J., and H. Watanabe. 1965. Studies on dielectric behaviour of wood. I. Effect of frequency and temperature on ϵ and ϵ. Mokuzai Gakkaishi.11(6):232-236.n
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