International peer-reviewed academic journals call for papers, http://www.iiste.org/Journals

1. Chemistry and Materials Research www.iiste.org
ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online)
Vol.3 No.7, 2013
40
Characterization of Electrical Properties of (PVA-LiF)
Composites
(1)
Ahmed Hashim, ( 2)
Amjed Marza, (3)
Bahaa H. Rabee ,(4)
Majeed Ali Habeeb, (5)
Nahida Abd-alkadhim,
(6)
Athraa Saad, (7)
Zainab Alramadhan
(1,3,4)
Babylon University, College of Education , Department of physics, Iraq.
(2,6)
Babylon University, College of Science , Department of chemistry, Iraq.
(5)
Babylon University, Enjineering Affairs, Iraq.
E-Mail: ahmed_taay@yahoo.com
Abstract
Composites consisting of poly-vinyl alcohol as matrix and lithium fluoride as a filler has been investigated with
different percentages of lithium fluoride are (0,5,10, and 15) wt.%. The electrical conductivity of composite has
been studied at different temperature. The results showed that the D.C electrical conductivity increases with
increasing the lithium fluoride concentrations and temperature. Also the activation energy change with
increasing of lithium fluoride concentration.
Keywords: Composites, Electrical Conductivity, lithium fluoride.
Introduction
In recent years, polymeric based composite materials are being used in many applications, such as
automotive, sporting goods, marine, electrical, industrial, construction, household appliances, etc. Polymeric
composites have high strength and stiffness, light weight, and high corrosion resistance. In the past decade,
extensive research work has been carried out on the natural fiber reinforced composite materials in many
applications. Natural fibers are available in abundance in nature and can be used to reinforce polymers to obtain
light and strong materials. Natural fibers from plants are beginning to find their way into commercial
applications such as automotive industries, household applications, etc. [1]. Poly(vinyl alcohol) (PVA), as it is
well known for its interesting behavior and its versatile applications. In water, there exist two possible
intermolecular interactions among PVA chains or between PVA and water, as follows: (1) H-bonding between
modified hydroxyl groups on PVA chains and (2) H-bonding between the —OH groups of PVA and water
molecules[2]. The present work deals with study the effect of lithium fluoride on the D.C electrical properties of
poly-vinyl alcohol composite.
Experiment
The materials which are used in this paper, is poly vinyl alcohol as matrix and lithium fluoride as a filler.
The weight percentages of lithium fluoride are (0,5,10 and 15)wt.%. Films of pure poly vinyl alcohol and poly
vinyl alcohol doped with lithium fluoride were prepared using casting technique thickness ranged between (213-
614)µm. The resistivity was measured over range of temperature from (30 to 80)o
C using Keithly electrometer
type (616C) .The volume electrical conductivity σν
defined by :
Where :
A = guard electrode effective area.
R = volume resistance (Ohm) .
L = average thickness of sample (cm) .
In this model the electrodes have circular area A= D2
π/4 where D= 0.5 cm2
.
The activation energy was calculated using equation :
σ = σo exp(-Ea/kBT)…………………..(2)
σ = electrical conductivity at T temperature
σ0 = electrical conductivity at absolute zero of temperature
KB = Boltzmann constant
Eact = Activation Energy
Results and Discussion
The variation of D.C electrical conductivity as function of concentration of lithium fluoride at temperature
(300
C) is shown in figure(1). The figure shows that the D.C electrical conductivity of the poly-vinyl alcohol
increases with increase Lithium Fluoride concentration.
)1.........(..........
1
RA
L
v
==
ρσν

2. Chemistry and Materials Research www.iiste.org
ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online)
Vol.3 No.7, 2013
41
The increment in D.C electrical conductivity of composite is ascribed to the rearrangement of lithium
fluoride particles throughout the polymer matrix. At low concentrations, the lithium fluoride particles are
represented by small darker region. Note also that the lithium fluoride concentration increases the darker regions
become larger and start to form some kind of network, when the lithium fluoride concentration is higher, the
network starts to connect to each other to form some kind of conductive path through the polymer matrix [3].
Figure (2) shows the variation of the bulk electrical conductivity of composite with temperature. The electrical
conductivity of composites increases with increase of temperature. This means that these materials have
resistance of negative thermal coefficient; that is, having the resistance decrease with the increase of
temperature. This is because polymer chains and lithium fluoride ions could act as traps for the moving charge
carriers by hopping process[4], with the increase of temperature, the motion of polymer chains increase; as a
result of the ions of lithium fluoride move. Consequently, the trapped charge carriers are releasing and the
conductivity of composite increase as a result for the increase of the charge carriers and mobility of these
charges[3].
Figure(3) shows the relationship between the ln(conductivity) and inverted absolute temperature of
composites of different concentration of lithium fluoride, the high values of activation energy are attributed to
1.E-12
1.E-11
1.E-10
1.E-09
0 3 6 9 12 15
Con. of LiFwt.%
Conductivity(S/cm)
FIG.1
Variation of D.C electrical conductivity with LiF wt.% concentration of composite.
1.E-12
1.E-11
1.E-10
1.E-09
30 40 50 60 70 80
T(c)
Conductivity(S/cm)
pure
5 wt.%
10 wt.%
15 wt.%
FIG.2
Variation of D.C electrical conductivity with temperature for(PVA-LiF ) composite

3. Chemistry and Materials Research www.iiste.org
ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online)
Vol.3 No.7, 2013
42
the existence of free ions in the polymer. By adding low concentrations of lithium fluoride, the values of the
activation energy are decreasing of composites as a result of the impact of space charge [5].
The addition of low concentrations creates local energy levels in the forbidden energy gap which act as
traps for charge carriers, which move by hopping among these levels. By increasing the lithium fluoride
concentrations, the activation energy decreases as a result of the increase of local centers [6], as shown in
figure(4)
Conclusions
1. The D.C electrical conductivity of the poly-vinyl alcohol increases by increasing the Lithium
Fluoride concentrations and the temperature.
2. The activation energy of D.C electrical conductivity decreases by increasing Lithium Fluoride
concentrations.
-29
-28
-27
-26
-25
-24
-23
-22
-21
2.8 2.9 3 3.1 3.2 3.3 3.4
1000/T(k)-1
ln(conductivity)
pure
5 wt.%
10 wt.%
15 wt.%
FIG.3
Variation of D.C electrical conductivity with resprocal absoute temperature for
( PVA-LiF) composite.
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 3 6 9 12 15
Con. of LiFwt.%
Ea(eV)
FIG.4
Variation activation energy for D.C electrical conductivity with LiF concentration of
composite

4. Chemistry and Materials Research www.iiste.org
ISSN 2224- 3224 (Print) ISSN 2225- 0956 (Online)
Vol.3 No.7, 2013
43
References
[1] Han-Seung Yang, Hyun-Joong Kim, Jungil Son, Hee-Jun Park Bum-Jae Lee, Taek-Sung Hwang, 2004,
"Rice-husk flour filled polypropylene composites, mechanical and morphological study", Composite Structures,
Vol.63, PP(305–312).
[2] Majdi K, Zeedan K. and Attar H., 1997,"Optical properties of poly thiophene/ PVC conducting polymer alloy
films", Iraqi J. of polym., Vol. 1, No. 1,155-162.
[3] Srivastava N. K. and Mehra R. M. , 2009," Study of electrical properties of polystyrene / foliated graphite
composite", J.Materials Science- Poland,Vol.27, No.1 Uni. Of Delhi South Campus.
[4] Wiley J., 1976 "Effect of Metal concentration on the Electrical conductivity and some mechanical properties
of poly methyl methacrylate- Copper composites", J. Of Appl. Poly. Vol.20.
[5] Ahmed M. S. and Zihilif A. M. , 1992, " The electrical conductivity of polypropylene and Nickel- Coated
carbon Fiber composite ",J. Mater. Sc. Vol. 25 , No. 706, Uni of Jordan , Amman , Jordan.
[6] Majdi and Fadhal , 1997," Iraqi .J . of polym " , vol. (1) , No (1) , P(15-20).

5. This academic article was published by The International Institute for Science,
Technology and Education (IISTE). The IISTE is a pioneer in the Open Access
Publishing service based in the U.S. and Europe. The aim of the institute is
Accelerating Global Knowledge Sharing.
More information about the publisher can be found in the IISTE’s homepage:
http://www.iiste.org
CALL FOR PAPERS
The IISTE is currently hosting more than 30 peer-reviewed academic journals and
collaborating with academic institutions around the world. There’s no deadline for
submission. Prospective authors of IISTE journals can find the submission
instruction on the following page: http://www.iiste.org/Journals/
The IISTE editorial team promises to the review and publish all the qualified
submissions in a fast manner. All the journals articles are available online to the
readers all over the world without financial, legal, or technical barriers other than
those inseparable from gaining access to the internet itself. Printed version of the
journals is also available upon request of readers and authors.
IISTE Knowledge Sharing Partners
EBSCO, Index Copernicus, Ulrich's Periodicals Directory, JournalTOCS, PKP Open
Archives Harvester, Bielefeld Academic Search Engine, Elektronische
Zeitschriftenbibliothek EZB, Open J-Gate, OCLC WorldCat, Universe Digtial
Library , NewJour, Google Scholar