Low Temperature Plasma Treatment: Jute fibres (Corchorus Olitorius or Tossa jute) were collected from the local market in Bangladesh. The fibres were introduced into a bell jar type capacitively coupled glow discharge reactor. To sustain a glow discharge i.e. for getting proper and uniform plasma, the conductive electrodes are separated 0.035 m apart from each other. In order to exposed all through uniform LTP treatment on the samples surface, the fibres (length of each fibre: 0.08 m) were inserted in between the two metallic electrodes by a carrier. After placing jute fibres between pair of electrodes, the glow discharge chamber was evacuated by a rotary pump at a pressure of 1.33 Pa. Ar was considered as plasma gas for treating the jute fibre. In all treatments, both process gases were introduced separately into the reaction chamber by a flow meter at a flow rate of 0.2 L/min. which is maintained by a needle valve. The discharge powers were adjusted at 50, 75 and 100 W at a line frequency of 50 Hz with the duration of exposure times of LTP treatment of fibres were 5, 10, 15 and 20 min. After plasma treatment has been finished, and the vacuum chamber was vented, jute samples were then removed and handled carefully in order to avoid possible surface contamination to the fibres. Later, the plasma treated fibres were immediately placed into a desiccator with the silica gel.
Sample Preparation: In preparing the samples, both raw and plasma treated jute fibres were cut into small pieces of sizes of about 1.0-2.0 mm. By mortar and pestle these small pieces of jute were ground, crushed and mixed in order to convert into powder form. Finally, the jute powders were sieved by a very fine and thin net to make the powder finer. The powdered form jute of about 200 mg. was then put in a specially prepared high-pressure die. In order to make the tablets from jute powder, a high pressure (14000 psi) was applied by a hydraulic press (Model: X30659, 0-16000 psi, Mold Pressure, P.S.I: 1" and 5/4" Mold, Will Corporation, NY, USA). The diameter and the thickness of each equipped tablet was 13.5 and 1.5 mm respectively. In these way thirteen types tablets (one tablet was for raw jute and another twelve were for LTP treated jute) were prepared with treated jute samples of different discharge powers and exposure times. All the tablets were oven-dried at 100 °C for 20 minutes before characterization of the samples.
Ultraviolet visible spectroscopic analysis: The current density-voltage (J-V) characteristics of tablet formed jute fibres were studied at room temperature in the voltage range of 5-100 V. The current pass through the tablet was measured by a high impedance Keithley 614 electrometer (Keithley Instruments, Inc.,USA) and the DC voltage was applied by an Agilent 6545A stabilized DC power supply (Agilent Technologies Japan Ltd, Tokyo, Japan). The voltage was increased step by step. The samples were depolarized before each measurement run.
(i) DC resistance: DC resistance (R) was calculated using the relation
R = V/I ........................(1)
where, V is the DC voltage (in V) and I (in A) is the current.
(ii) DC resistivity: DC resistivity (ρ) was calculated using the relation
R =ρ( L/A) ......................(2)
where, R is the DC resistance (in Ω), ρ is the DC resistivity (in Ω-m), L (in m) is the thickness of the jute tablet and A (in m2) is the cross-sectional area of the tablet.
From equation (1) and (2) resistivity, ρ can be calculated as
ρ = (V/I) X (A/L) ..........................(3)