Author: Jayaramudu, J; Ramana, C H V V; Varadarajulu, A
Date published: February 1, 2010
Grewia tilifolia is a tree found in India, Sri Lanka, tropical Africa, Burma, and Nepal. Its bark, wood, fruits; leaves, and roots are used ethnomedically. The bark is used in Ayurvedic medicine to treat vitiated conditions of Pitta and Kapha, burning sensation, cough, skin diseases, wounds, ulcers, diarrhoea, seminal weakness, general debility, and hypertension [1-4]. The mucilage and the hot water extract of the bark are used as an antidote for opium poisoning in human adults . The stem bark is used to treat spermatorrhoea, in Bahraich, U.P., India, in human adults . Several biological properties of the bark have been studied [7-8]. Fibers are the subject of study in relation to electrical and dielectric behaviour for a long time. Research on the electrical and dielectric properties of such materials has been carried out in many directions, which range from characterizing the fiber/fabric to the application of its dielectric properties in many diverse fields. The present paper is to summaries the most recent developments in the field of Efforts are being made to develop anticancer agents from Grewia tilifolia, in particular their application in biology and medicine.
The fabric extracted from the branches of the tree Grewia tilifolia, Sodium Hydroxide pellets (Merk specialities private limited, Mumbai, India) Benzene, Sodium Chlorite, Acetic acid, Sodium bisulphate and Ethanol S.d.fine-Chem Limited, Mumbai, India were the materials used in the present work. The new natural fabric Grewia tilifolia tree is shown in Fig. 1 .
1.2. Extraction of the Fabric from the Tree
The fabric samples of Grewia tilifolia were extracted from the bark of the tree. They were kept in water for a week to remove the dirt and other foreign material. They were then thoroughly washed and dried in the sun for a week. Some of the samples were treated with 5% NaOH solution (by weight) at a maximum temperature of 30 °C and a hold time of 45 min and after treatment, the fabrics were thoroughly washed and then dried at 80 °C for 24 h and stored. The samples were also redried before analysis. This uniaxial fabric was analyzed by Chemical, Fourier transform infrared spectroscopy, Thermogravimetric analysis, X-ray diffraction, Scanning electron microscopy and polarized optical microscopic techniques are published .
The ratio of the voltage phasor to the electric current phasor. A phasor is a constant complex number, usually expressed in exponential form, representing the complex amplitude (magnitude and phase) of a sinusoidal function of time. Phasors are used by electrical engineers to simplify computations involving sinusoids, where they can often reduce a differential equation problem to an algebraic one.
1.4. AC Conductivity
AC Conductivity is one of the studies done on solids in order to characterize the bulk resistance of the crystalline sample. This study also gives information on electrical properties of materials and their interface with electronically conducting electrodes.
1.5. Dielectric Constant
The dielectric constant is an essential piece of information when designing capacitors, and in other circumstances where a material might be expected to introduce capacitance into a circuit. If a material with a high dielectric constant is placed in an electric field, the magnitude of that field will be measurably reduced within the volume of the dielectric. This fact is commonly used to increase the capacitance of a particular capacitor design.
1.6. Dielectric Loss
Dielectric loss due to movement or rotation of the atoms or molecules in an alternating electric field. A loss of energy that eventually produces a rise in temperature of a dielectric placed in an alternating electrical field.
Dielectric materials have many important functions in the microelectronics industry. New packaging technology requires substrates with low permittivity, interconnections made of high-conductivity metals, high wiring density, and embedded passive circuit elements.
2.1. Electrical and Dielectric Properties of Fiber Measurements
The experimental set-up for the measurement of electrical and dielectric properties of new natural cellulosic fabric Grewia tilifolia is shown in Fig. 2. A commercial digital LCR meter (HIOKI 3532-50 LCR Hi Tester, Koizumi, Japan) was used to measure the electrical properties (Impedance & AC Conductivity) and dielectric properties (capacitance and dissipation factor (D)) .
The fabric samples were measured as a function of frequency in the range from 1 kHz to 500 kHz, temperature in the range from 30 °C to 210 °C. Impedance, X, RS, capacitance and dissipation factor were measured with the sample in the cell.
The dielectric constant (e') of the samples are calculated using the formula (1)
ε' = C^sub p^ d / ε^sub 0^ A, (1)
C^sub p^ = Parallel capacitance of the cell with the sample;
d = Thickness of the sample;
ε^sub 0^ = 8.854X10^sup -12^ F/m;
A = Area of the sample.
The AC conductivity (σ^sub ac^) of the samples are calculated using the formula (2)
σac = [X^sup 2^ / (X^sup 2^ + RS^sup 2^)] * [t/A], (2)
X = Real;
RS = Series Resistance;
T = Thickness of the sample;
A = Area of the sample.
3. Results and Discussion
The graphical results of electrical (Impedance & AC Conductivity) and dielectric (Dielectric constant & Dielectric loss) properties of Grewia tilifolia fabric samples in untreated / treated condition are presented in Figs. 3, 4, 5, 6, 7, 8 9, and 10 respectively. The parameters were determined at a frequency range of 1 KHz to 500 KHz at variable temperature range of 30 °C to 210 °C.
The Impedance for untreated / treated Grewia tilifolia fabric was determined at a frequency range of 1 kHz to 500 kHz at variable temperature range of 30 0C to 210 0C. The graphs are drawn between temperature verses impedance for untreated / treated fabric samples in Figs. 3 and 4 respectively. From Fig. 4, we conclude that there is an electronic polarization at frequencies 1 kHz, 5 kHz and 10 kHz at 75 °C temperature for treated, because in treated the lignin was removed. The AC conductivity for untreated / treated Grewia tilifolia fabric was determined at a frequency range of 1 kHz to 500 kHz at variable temperature range of 30 °C to 210 °C. The graphs are drawn between temperature verses AC Conductivity for untreated / treated fabric samples in Fig. 5 and 6 respectively. From Fig. 6, we conclude that lattice is decreased and large polaron hopping at frequency 500 kHz at 70 °C temperature for treated, because in treated the hemicellulose decreased. The Dielectric Constant for untreated / treated Grewia tilifolia fabric was determined at a frequency range of 1 kHz to 500 kHz at variable temperature range of 30 °C to 210 °C. The graphs are drawn between temperature verses dielectric constant for untreated / treated fabric samples in Figs. 7 and 8 respectively.
From Fig. 8, we conclude that the fabric is frequency dependent. The molecules decreased with increase in temperature, leading to the decrease in dielectric constant for treated. The Dielectric Loss for untreated / treated Grewia tilifolia fabric was determined at a frequency range of 1 kHz to 500 kHz at variable temperature range of 30 °C to 210 °C. The graphs are drawn between temperature verses dielectric loss for untreated / treated fabric samples in Figs. 9 and 10 respectively. From Fig. 10, we conclude that there is a constant dielectric loss at frequency 100 kHz for entire temperature range for treated, because in treated the lignin and hemicellulose was removed.
The Impedance, AC conductivity, Dielectric constant and Dielectric loss for untreated Grewia tilifolia fabric are shown in Figs. 3, 5, 7 and 9 respectively. The untreated Grewia tilifolia fabric contains lignin and hemicellulose.
The results of electrical and dielectric properties of Grewia tilifolia fabric for untreated / treated determined at a frequency range of 1 kHz to 500 kHz at variable temperature range of 30 0C to 210 0C using LCR meter (HIOKI 3532-50 LCR Hi Tester, Koizumi, Japan). When lignin and hemicellulose removed from the fabric there is an electronic polarization, lattice decrease and large polaron hopping occurred in electrical properties and frequency dependent, the molecules decreased with increase in temperature, leading to the decrease in dielectric constant and constant dielectric loss at frequency 100 KHz for entire temperature range appeared in dielectric properties. The present paper constitutes a step towards the most recent developments in the field of Efforts are being made to develop anticancer agents from Grewia tilifolia, in particular their application in biology and medicine.
This work was supported by University Grants Commission (UGC) of India sponsored Major Research Project. No 33-397/ 2007 (SR).
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. LCR Meter (HIOKI 3532-50 LCR Hi Tester, Koizumi, Japan).
JAYARAMUDU J., 1V. V. RAMANA CH. and VARAD ARAJULU A.
Natural Fiber Laboratory, Department of Polymer Science & Technology, Sri Krishnadevaraya
University, Anantapur- 515 055, Andhra Pradesh, India
1 Scientific Instrumentation Laboratory, Department of Instrumentation, Sri Krishnadevaraya
University, Anantapur- 515 055, Andhra Pradesh, India
Received: 31 January 201 0 /Accepted: 1 9 February 201 0 /Published: 26 February 2010