Ionic Conduction in Polymer Composite

Ionic Conduction in Polymers Composite

Omed Gh. Abdullah

University of SulaimaniCollege of Science

Physics Department

STUDY THE EFFECT OF TEMPERATURE AND FREQUENCY ON THE DIELECTRIC PROPERTIES OF SOME COMMERCIAL

POLYMERS

A THESIS SUBMITTED TO THE COUNCIL OF

COLLEGE OF SCIENCE UNIVERSITY OF SULAIMANIIN PARTIAL FULFILMENT OF REQUIREMENTS FOR

THE DEGREE OF MASTER OF SCIENCE IN PHYSICS

BYSHUJAH-ALDEEN BAKIR AZIZ

B.Sc. IN PHYSICS-2003(Sulaimani University)

UNDER SUPERVISION OF:Prof. Dr. HAMEED MAJID AHMED

September Gelawezh 2007 2707

OPTICAL AND ELECTRICAL PROPERTIES OF SEMICONDUCTING OXIDE GLASSES

A THESIS

SUBMITTED TO THE COUNCIL OF COLLEGE OF SCIENCE UNIVERSITY OF SULAIMANI

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN PHYSICS

BYDANA ABDULLA TAHIR

(M. Sc.) in physics

Salahaddin University-1995

UNDER SUPERVISION OF: MANAF ABD HASSAN AHMAD AL-ANI

Assistant Professor Lecturer

September Galawezh2007 2707

Dielectric analysis of Polystyrene polymer film

Dana A. Tahir, Omed Gh. Abdullah, and Shuja-Aldeen B. Aziz

Department of Physics, College of Science, Sulaimani University

AbstractIn this work an attempt has been made to study the various dielectric

parameters of polystyrene film. The dielectric constant , dielectric loss and loss tangent have been determined in the frequency range (1-000)KHz at different temperatures. The frequency dependent conductivity was also measured to characterize the polymer. The complex impedance plot (cole-cole plot) was used to calculate the static dielectric constant , infinitely large frequency dielectric constant and relaxation times. Finally the results are analyzed in terms of different parameters.

Key words: polymer film, dielectric constant, dielectric loss, relaxation, activation energy

Optical and Electrical Properties of Polyvinyl-chloride (PVC) films

Omed Gh. Abdullah, Dana A. Tahir, and Shuja-Aldeen B. Aziz

Department of Physics, College of Science, Sulaimani University

AbstractThe optical properties of the polyvinyl-chloride thin films were studied which include their

absorbance, transmittance, reflectance spectra, band gap, and refractive index, before and after annealing at T=75oC for 24hrs. The films were found to exhibit high transmittance, low absorbance and low reflectance in the visible, and near infrared region up to 1100nm. However, the absorbance of the films was found to be high in the ultra violet region with peak around 306nm. The dielectric constant, dielectric loss, and ac conductivity of polyvinyl-chloride were obtained at different frequencies and temperatures. The experimental results show that e’ and e” decreased with increasing frequency, which indicates that the major contribution to the polarization comes from orientation polarization. The value of e’ increased with increasing temperature, which is due to great freedom of movement of the dipole molecular chains at high temperature.

Key words: thin film, optical properties, electrical properties, complex permittivity.

Debye behavior

Cole-Cole plot for Polystyrene at different temperatures.

International Journal of Materials ScienceISSN 0973-4589 Volume 5, Number 4 (2010), pp. 537–545© Research India Publicationshttp://www.ripublication.com/ijoms.htm

Physical Properties of Pure and Copper Oxide DopedPolystyrene Films

Omed Gh. Abdullah and Dana S. MuhammadDepartment of Physics, College of Science, University of Sulaimani - Iraq

Abstract

The UV/VIS optical absorption for difference compositions copper oxide doped polystyrene thin films were studied in the wavelength 200-1000 nm. It was found that the optical absorption is due to direct allowed transitions, and the energy gaps shows nonlinear behavior with copper oxide concentration, optical energy gap showed a decreasing trend with increased dopant concentration up to 10% of the dopant, for further increase in dopant concentration this value started increasing again due to segregation effects. The annealing of the samples at temperature 90oC for 4 hr, caused the decrease in energy gaps. The studies of the real and imaginary parts of the dielectric constants showed that they are also affected by copper oxide concentration.

Key words: optical properties, polymer composite, doping, complex dielectric constant.

Absorption Spectrum

Optical absorption for PS with different CuO content, as a function of wavelength.

265 275 285 295 305 315 325 335 345 355 3650

0.050.1

0.150.2

0.250.3

0.350.4

0.450.5

PS-0%CuOPS-5%CuOPS-10%CuOPS-15%CuO

Wavelength (nm)

Abs

orba

nce

Optical Band Gaps

Optical energy gap of direct allowed transition, and tail localized state energy against copper oxide concentration, of pure and

doped polymer film before (solid line), and after annealing (dashed line).

0 5 10 15 20 254.45

4.46

4.47

4.48

4.49

0

0.05

0.1

0.15

0.2

0.25

CuO concentration %

Eop

t

Et

Effect of Zirconia concentration on optical properties of Polystyrene films

Omed Gh. Abdullah and Dlear R. SaberDepartment of Physics, College of Science, University of Sulaimani - Iraq

AbstractOptical properties of prepared Polystyrene (PS) films with different filling levels of

Zirconia have been investigated in the visible and ultraviolent wavelength regions. It was found that the optical absorption is due to direct-allowed transitions, and the energy gaps decrease with increasing Zirconia content for all transitions, while the width of the tail localized states increase with increasing Zirconia content. The band gap of all films shows to be decrease after thermal treatment. The optical constants refractive index n, extinction coefficient K, have been also calculated. The refractive index increased in the composite samples as compared with the pure PS sample prepared by the same method.

Key words: polymer, optical properties, filler, extinction coefficient, annealing. PACS: 78.20.Ci

Refractive index

Refractive index as a function of wavelength for PS for different Zirconia content.

250 350 450 550 650 750 850 950 10501

1.5

2

2.5

3

Wavelength (nm)

n (R

efre

ctiv

e In

dex)

PS-0% ZrO2

PS-5% ZrO2

PS-10% ZrO2

PS-15% ZrO2

PS-20% ZrO2

Refractive index

Refractive index as a function of wavelength for PS for different Zirconia content.

250 350 450 550 650 750 850 950 10501

1.5

2

2.5

3

Wavelength (nm)

n (R

efre

ctiv

e In

dex)

PS-0% ZrO2

PS-5% ZrO2

PS-10% ZrO2

PS-15% ZrO2

PS-20% ZrO2

Since the refractive index of this composite was controllable it can be used to fabricate waveguides with the desired refractive index contrast between the core and the cladding

Optical band Gap

The optical gap, and tail localized state as a function of Zirconia content, before (solid line) and after annealing (dashed line).

0 5 10 15 20 254.32

4.34

4.36

4.38

4.4

4.42

4.44

4.46

4.48

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

ZrO2 %

Eopt

(eV)

Et (e

V)

Variation of Optical Band Gap Width of PVA films Doped with Aluminum Iodide

Omed Gh. Abdullah and Sarkawt Abubakr HussenDepartment of Physics, College of Science, University of Sulaimani - Iraq

AbstractPolymer composite of polyvinyl alcohol (PVA), Aluminum Iodide have been prepared by solution cast method for

different doping concentrations. The absorption of pure and doped films have been investigated in the visible and ultraviolent wavelength regions. It was found that the optical absorption is due to direct and indirect transitions, and the optical energy gaps values shifted to lower energies on Aluminum Iodide doping concentration for all transitions, while the band edge width of the tail localized states increase with increasing Aluminum Iodide concentration. The band gap of all films shows to be decrease after thermal treatment. The optical constants refractive index n, extinction coefficient K, the complex dielectric constant have been also calculated. The dielectric constant increased in the composite samples as compared with the pure PVA sample prepared by the same method.

Key words: polymer composite, optical properties, doping, complex dielectric constant.

Absorption Spectrum

Optical absorption as a function of wavelength for PVA at different Aluminum Iodide content.

200 210 220 230 240 250 260 270 280 290 3000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

PVA-0%AlI

PVA-5%AlI

PVA-10%AlI

PVA-15%AlI

PVA-20%AlI

Wavelength (nm)

Abs

orba

nce

(a.u

.) PVA-0%AlI3

PVA-5%AlI3

PVA-10%AlI3

PVA-15%AlI3

PVA-20%AlI3

Direct Optical Band Gaps

Direct optical band gaps for PVA with Aluminum Iodide content.

5 5.25 5.5 5.75 6 6.25 6.50

102030405060708090

100

PVA-0%AlI

PVA-5%AlI

PVA-10%AlI

PVA-15%AlI

PVA-20%AlI

hv (eV)

(ahv

)2

(10

4)

Indirect Optical Band Gaps

Indirect optical band gaps of PVA with Aluminum Iodide content.

5 5.25 5.5 5.75 6 6.25 6.50

5

10

15

20

25

30

35

40PVA-0%AlIPVA-5%AlIPVA-10%AlIPVA-15%AlIPVA-20%AlI

hv (eV)

(ahv

)1/2

Band tails of localized states

Natural logarithm of absorption coefficient as a function of photon energy.

5.1 5.15 5.2 5.25 5.3 5.35 5.41

1.5

2

2.5

3

3.5

4

4.5

5

5.5PVA-0%AlI4PVA-5%AlI4PVA-10%AlI4PVA-15%AlI4PVA-20%AlI4

hv (eV)

ln(a

)

Dielectric properties of Polyester reinforced with Carbon black particles

Omed Gh. Abdullah, Gelas M. Jamal, Dana A. Tahir, and Salah Raza SaeedDepartment of Physics, College of Science, University of Sulaimani - Iraq

AbstractDielectric constant and conductivity of Polyester doped with carbon black are

investigated in the frequency range (0.5-1000) KHz and within the temperature range (28-80)oC. Dielectric permittivity and loss tangent are found to be decrease with increasing frequency and increase with increasing temperature. The ac conductivity is found to be frequency-independent for low frequency however vary with frequency as ws, beyond a critical value. The frequency exponential factor was estimated and it was found to vary between 0.63 and 0.77, indicating a dominant hopping process at low temperatures. From the temperature dependence of dc conductivity, the increase of activation energy was observed with carbon black concentrations.

Key words: ac conductivity, polyester, carbon black, dielectric constant.

Complex Dielectric Constant

log f

e’

e”

log f

fmax

Permittivity or Dielectric Constant

At high frequencies dipoles cannot return rapidly enough - charging cannot occur/dielectric constant is low

Frequency at which dipoles respond to the field

At high frequencies, dipoles cannot move rapidly enough to respond – lossesare low

e’ and e” as a functionof frequency – at constant temperature

Permanent dipoles FOLLOW variations in the AC field – hence current and voltage out of phase – losses low

Losses

Frequency at which permittivity drops and losses increase is where the polymer is said to show dispersion

At low frequencies dipoles can align -- dielectric constantis high

ac conductivity virus concentration

ac conductivity dependence on black carbon concentration at different temperatures

0 2 4 6 8 10 12 14 16 18 200

10

20

30

40

50

60

70t=26 C

t=40 C

t=60 C

t=80 C

BC % Concentration

sac

(s/m 1

0-6)

ac conductivity virus frequency

Dependence of frequency on the ac conductivity at different temperatures of Polyester film doped with of Carbon black

3.25 3.75 4.25 4.75 5.25 5.75 6.25 6.75-6.5

-6

-5.5

-5

-4.5

-4

T=26 CT=40 CT=60 CT=80 C

log(w)

log(

sac)

𝝈′ሺ𝝎,𝑻ሻ= 𝝈𝒅𝒄ሺ𝑻ሻ+ 𝑨𝝎𝒔

ac conductivity virus frequency𝝈′ሺ𝝎,𝑻ሻ= 𝝈𝒅𝒄ሺ𝑻ሻ+ 𝑨𝝎𝒔

The variation of the exponent 𝒔 with temperature gives information on the specific mechanism involved. The exponential factor 𝒔 was calculated from slope of Fig. at high frequency, and it was found to be 𝟎.𝟕𝟕, 𝟎.𝟕𝟓, 𝟎.𝟕𝟎, and 𝟎.𝟔𝟑 for the temperature (𝟐𝟔,𝟒𝟎,𝟔𝟎,𝒂𝒏𝒅 𝟖𝟎)𝒐𝑪 respectively; indicating that 𝒔 is weakly decreasing function of temperature. This could be attributed that at higher temperature, high mobility of free charges make them more frequency independent conductivity which as a result increases 𝒅𝒄 conductivity.

ac conductivity virus temperature

Semilogarithmic plots of dc conductivity against reciprocal of temperature at different Carbon black concentrations

2.8 2.9 3 3.1 3.2 3.3 3.4-9.00

-8.50

-8.00

-7.50

-7.00

-6.50

-6.00

-5.50

-5.00

0%CBLinear ( 0%CB) 6%CBLinear ( 6%CB) 12%CBLinear ( 12%CB) 18%CB

1000/T (1/K)

log(

sdc)

𝝈𝒅𝒄 = 𝝈𝒐 𝐞𝐱𝐩൬− 𝑬𝒄𝒌𝑻൰

ac conductivity virus temperature𝝈𝒅𝒄 = 𝝈𝒐 𝐞𝐱𝐩൬− 𝑬𝒄𝒌𝑻൰

From the slope of parallel straight line with negative slope, the activation energy 𝑬𝒄 is calculated. The values of 𝑬𝒄 is essentially dependent of black carbon concentrations and of a value (𝟎.𝟏𝟏𝟔,𝟎.𝟏𝟕𝟔,𝟎.𝟐𝟕𝟖,𝟎.𝟑𝟏𝟗) 𝒆𝑽 for the ሺ𝟎,𝟔,𝟏𝟐,𝟏𝟖ሻ% CB, respectively. It was clear that activation energy value increases with increasing the CB content. The addition of CB to Polyester host enhances the electrical conduction of Polyester host due to the electronic and impurity contributions arising from the CB.

OCH2CH2OC(CH2)COO O n

CH2CH2COO n

Conclusion

The main observation in this study worth to be mentioned relates to the relative value of electrical conductivity versus the carbon black contents; it was observed that even low amount of carbon black able to maximize the conductivity of the composite up to three orders of magnitude, we conclude that polyester carbon black composite is a good candidate and alternative way for obtaining conducting organic composites at low cost.

Optical absorption of polyvinyl alcohol films doped with Nickel Chloride

Omed Gh. Abdullah, and Dlear R. SaberDepartment of Physics, College of Science, University of Sulaimani - Iraq

AbstractFilms of pure and doped Polyvinyl alcohol (PVA) with different concentration of Nickel

Chloride (NiCl2) were prepared using the casting technique, in order to investigate effect of NiCl2 additions on the optical properties of PVA host. The dispersion studies of pure PVA film and PVA films doped with NiCl2 were investigated using complex refractive index in the wavelength range 190-1100 nm. The absorption spectral analysis showed that the optical band was from the direct and indirect allowed optical transitions. The optical band gap of the films decreases with increasing NiCl2 contents, while the Urbach energy called the width of localized states in the optical band gap decreases from 0.7414 to 0.1891 eV. Consequently, the optical constants and optical band gap of the samples change with the annealing temperatures.

Key words: absorbance, PVA, dopand, optical band gap.

UV/VIS Optical Absorption Spectra

The optical absorption coefficient spectrum of PVA-NiCl2 composites

190 240 290 340 390 440 490-2.77555756156289E-17

0.00999999999999998

0.02

0.03

0.04

0.05

PVA-0%NiCl2PVA-5%NiCl2PVA-10%NiCl2PVA-15%NiCl2

Wavelength (nm)

Abs

orba

nce

(a.u

.)

PVA-0%NiCl2

PVA-5%NiCl2

PVA-10%NiCl2

PVA-15%NiCl2

UV/VIS Optical Absorption Spectra

The optical absorption coefficient spectrum of PVA-NiCl2 composites

190 240 290 340 390 440 490-2.77555756156289E-17

0.00999999999999998

0.02

0.03

0.04

0.05

PVA-0%NiCl2PVA-5%NiCl2PVA-10%NiCl2PVA-15%NiCl2

Wavelength (nm)

Abs

orba

nce

(a.u

.)

PVA-0%NiCl2

PVA-5%NiCl2

PVA-10%NiCl2

PVA-15%NiCl2

UV/VIS Optical Absorption Spectra

The optical absorption coefficient spectrum of PVA-NiCl2 composites

190 240 290 340 390 440 490-2.77555756156289E-17

0.00999999999999998

0.02

0.03

0.04

0.05

PVA-0%NiCl2PVA-5%NiCl2PVA-10%NiCl2PVA-15%NiCl2

Wavelength (nm)

Abs

orba

nce

(a.u

.)

PVA-0%NiCl2

PVA-5%NiCl2

PVA-10%NiCl2

PVA-15%NiCl2

Two conditions to become conductive:1-The first condition for this is that the polymer consists of

alternating single and double bonds, called conjugated double bonds.

In conjugation, the bonds between the carbon atoms are alternately single and double. Every bond contains a localised “sigma” (σ) bond which forms a strong chemical bond. In addition, every double bond also contains a less strongly localised “pi” (π) bond which is weaker.

2-The second condition is that the plastic has to be disturbed - either by removing electrons from (oxidation), or inserting them into (reduction), the material. The process is known as

Doping. There are two types of doping:

1-oxidation with halogen (or p-doping).

2- Reduction with alkali metal (called n-doping).

( ) ( ) - xNaCHxNaCH xnn

( ) ( ) - 323 ICHIxCH nn

Two conditions to become conductive:

Factors that affect the conductivity

1-Denesity of charge carriers.2- Thier mobility.3-The direction.4- Presence of doping materials (additives that

facilitate the polymer conductivity)5-Temperature.

Electrical characterization of polyvinyl alcohol films doped with sodium iodide

Omed Gh. AbdullahDepartment of Physics, College of Science, University of Sulaimani - Iraq

AbstractPolyvinyl alcohol (PVA) films doped with sodium iodide up to (30wt%) were prepared in

order to investigate the effect of sodium iodide additions on the electrical properties of PVA host. The dielectric permittivity, dielectric loss, electric modulus and ac conductivity were studied in the frequency range 20KHZ-1MHz and in temperature range 300-350 K. Upon increasing the contents of sodium iodide an increase in the dielectric permittivity, dielectric loss and ac conductivity of PVA host are observed. The ac conductivity is found to obey power law Bws. The frequency exponential factor s was estimated and it was found to vary between 0.92 and 0.34, dependence on sodium iodide contents. From the temperature dependence of ac conductivity, the increase of activation energy was observed with dopant concentration.

Key words: ac conductivity, electric modulus, complex dielectric constants, doping.

ac conductivity virus frequency

Variation of ac conductivity with frequency for PVA-NaI composites

0 100 200 300 400 500 600 700 800 900 10000

102030405060708090

100

PVA-0%NaIPVA-10%NaIPVA-20%NaIPVA-30%NaI

f (KHz)

sac

s/m

(10-6)

C C

H OH

H H

n

Activation Energy

Semilogarithmic plots of dc conductivity against reciprocal of temperature at different NaI concentrations

𝝈𝒅𝒄 = 𝝈𝒐 𝐞𝐱𝐩൬− 𝑬𝒄𝒌𝑻൰

2.8 2.9 3 3.1 3.2 3.3 3.4-6

-5

-4

-3

-2

-1

0PVA-0%NaILinear (PVA-0%NaI)PVA-10%NaILinear (PVA-10%NaI)PVA-20%NaI

1000/T (K-1)

log(

sdc)

Activation Energy

Table(1): Values of activation energy (Ea) and the exponential factor (s) for PVA-NaI composites.

𝝈𝒅𝒄 = 𝝈𝒐 𝐞𝐱𝐩൬− 𝑬𝒄𝒌𝑻൰

Samples 𝐸𝑎 (𝑒𝑉) (𝑠) 𝑃𝑉𝐴− 0% 𝑁𝑎𝐼 𝟎.𝟓𝟐 0.92 𝑃𝑉𝐴− 10% 𝑁𝑎𝐼 𝟎.𝟖𝟑 0.87 𝑃𝑉𝐴− 20% 𝑁𝑎𝐼 𝟏.𝟎𝟔 0.63 𝑃𝑉𝐴− 30% 𝑁𝑎𝐼 𝟏.𝟐𝟎 0.34

𝝈′ሺ𝝎,𝑻ሻ= 𝝈𝒅𝒄ሺ𝑻ሻ+ 𝑨𝝎𝒔

Electric Modulus

Argand plots of (a) pure PVA, (b) 10 wt%, (c) 20 wt% and (d) 30 wt% NaI-PVA composites.

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.40

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

T=300 KT=310 KT=320 KT=330 KT=340 KT=350 K

M'

M"

(a)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.350

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

T=300 KT=310 KT=320 KT=330 KT=340 KT=350 K

M'

M"

(b)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.350

0.01

0.02

0.03

0.04

0.05

0.06

0.07

T=300 KT=310 KT=320 KT=330 KT=340 KT=350 K

M'

M"

(c)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.40

0.02

0.04

0.06

0.08

0.1

0.12

T=300 KT=310 KT=320 KT=330 KT=340 KT=350 K

M'

M"

(d)

Tanks for your attention

Material Group