ICA – POSTER 406 Acoustics and Dielectric properties of Borassus Flabellifier ‘ BF ’ with frequency at 308 K .
Dielectric properties of Borassus Flabellifier ‘BF’ wood were carried out by authors with frequency at room temperature 308K. The wood section is taken from ma le BF tree and female BF tree from where the natura l j ice is collected over night. A large variation occurs at f requencies less than 10 Hz. at room temperature 308 K.The dielectric constant decreased as frequency increase d from 1 Hz to 4.0 x10 Hz. The minimum peak value of the dielectric loss tangents shifted towards higher fre quencies at room temperature 308K. Very low dielect ric conductivity has been observed. Characterization of the samples was made by scanning electron microsco pe (SEM) Model JEOL JSM5400. Results shows that the dielectr ic properties are slight different in male and fema le BF wood considerably. The variation of the dielectric const a t in different wood structures is correlated at r oom temperature with the frequency variations in a way the received signal strength. Acoustics measurement were carrie d out in our laboratory using Ultrasonic Interferometer by NDT t echnique and the dielectric measuring device used i n this study at UGC-DAE Consortium for Scientific Research Centr Indore (M.P.) India. In this study the drying of wood done by microwave energy using a continuous microwave dr i r was compared to that by conventional method.
THERMAL AND DIELECTRIC PROPERTIES OF PINE WOOD IN THE TRANSVERSE DIRECTION
In this paper, the thermal conductivity and dielectric parameters for pine [Pinus sylvestris (L.)] woods were determined in transverse directions for moisture conditions from oven-dry to 22 percent at a room temperature of 22 to 24 °C. Results indicate that the behaviors of thermal conductivity and dielectric parameters with moisture content and structural directions were similar. In general, the properties increased within the range studied with increasing moisture content. The radial values were similar to tangential values for both thermal conductivity and dielectric properties. The data presented here should be useful in most design problems where pine wood is subjected to microwave electric fields and heat changes.
Dielectric and ultrasonic properties of rubber wood. Effect of moisture content grain direction and frequency
Dielectric properties of rubber wood have been studied at low and microwave frequencies with different moisture content and grain direction. The ultrasonic properties were studied with pulsed longitudinal waves of frequency 45 kHz, Two anisotropic directions have been considered for this study — parallel and perpendicular to grain. The low frequencies were of 0.01, 0.1, L0, 10 and 100 Hz and microwave frequencies were of 1, 2.45, 6, 8, 10, 14 and 17 GHz. The moisture content affected the dielectric constant and dielectric loss factor both at low and microwave frequencies? The moisture content above 30% showed little influence on dielectric properties whereas it increases linearly from 0 to 30% in both the grain directions at low frequencies. A continuous increase of dielectric properties was obtained with the increase of moisture content at microwave frequencies and the trend becomes concave upward. Dielectric properties increase as the frequencies increase except dielectric loss factor at microwave frequencies where reverse trends were observed. Little change of dielectric loss factor was obtained at frequencies above 6 GHz. The parallel to grain direction showed higher dielectric constant and dielectric loss factor compared to perpendicular to grain direction. This dielectric anisotropy of wood may be attributed due to the microscopic, macroscopic molecular as well as chemical constituents of wood. Ultrasonic properties were also affected considerably by the moisture content and grain direction. The dried wood showed higher ultrasonic velocity and elastic stiffness constant compared to green wood. The parallel to grain direction exhibits higher ultrasonic velocity and elastic stiffness constant than perpendicular to grain.ZusammenfassungDie dielektrischen Eigenschaften von Hevea brasiliensis wurden bei niedriger und Mikrowellenfrequenz sowie unterschiedlichen Feuchten und Faserrrichtungen untersucht. Die Ultraschalleigenschaften wurden mit gepulsten Longitudinalwellen von 45 kHz bestimmt. Beide Bestimmungen erfolgten parallel und senkrecht zur Faser. Als niedrige Frequenzen wurden 0,01, 0,1, 1,0, 10 und 100 Hz eingesetzt, im Mikrowellenbereich 1, 2, 4, 5, 6, 8, 10, 14 und 17 GHz. Die Feuchte beeinflußt die Dielektrizitätskonstante und den Verlustfaktor in beiden Frequenzbereichen. Zwischen 0 und 30% Feuchte steigt die Dielektrizitätskonstante bei niedrigen Frequenzen linear