International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014 ISSN 2319 - 4847
2
3
M. J. Kadhim*, A. K. Abdullah, I. A. Al-Ajaj, and A. S. Khalil
Department of Physics, College of Science, University of Baghdad, Iraq
EP /Al
2
O
3
nanocomposites with different weight percentage of Al
2
O
3
nanoparticles 1, 2, 3, 4, 5, and 7%wt. of Al
2
O
3
nanoparticles with average particle size smaller than 46.73 nm had been prepared. EP/ Al
2
O
3
nanocomposites samples with good dispersion of nanoparticles in the epoxy matrix were prepared and experiment performed to measure the dielectric permittivity and tan delta over frequency (10
3
-10
6
) Hz .Relative permittivity of EP/Al
2
O
3
nanocomposites at 1wt% is lower than that of unfilled epoxy.
Relative permittivity at 2, 3, and 4%wt. of Al
2
O
3
nanoparticle increased with increasing weight percentage of Al
2
O
3
nanoparticles respectively. At 5 and 7%wt. relative permittivity decreased again. Tan delta decrease with increasing particle contains of Al
2
O
3 nanoparticles until reached 5%wt. tan delta begin to increase but still less than of unfilled epoxy. This surprising observation has been attributed to the interaction between epoxy chains and the nanoparticles, and in this paper this phenomena is analyzed using dual layer interface model reported for polymer nanocomposites, the nanofiller loading seems to have significant effect. Further analysis of results obtained in this paper shows that the possible of interaction between nanoparticle and epoxy chains by using
Fourier Transform Spectroscopy (FTIR) .
Keywords: Epoxy, Dielectric properties, Nanocomposite, Al
2
O
3
nanoparticles.
Epoxy resin is a thermosetting epoxide polymer that contains two or more epoxide groups. It's one of the most commonly used thermosetting macromolecular synthetic materials. Epoxy resin has properties of excellent adhesiveness, mechanical property, and chemical stability. It also has advantages such as low contraction percentage, low cost, and easy shaping etc. It is widely used in application areas such as dielectric materials, anticorrosion, aerospace, shaping, coating materials and other industrial areas, and becomes one of essential materials for industrial application [1]. In the last decade many research teams from all over the world have focused their energies toward studies on polymer nanocomposites as effective materials for electrical insulation [2]. Several dielectric properties have been evaluated and the permittivity and tan delta values in nanocomposites are reported to be lower than that of base epoxy and microcomposites when insulating oxides are used as the fillers are dispersed in epoxy [3]. The higher permittivity of nanocomposite would be mainly attributed to permittivity of metal oxide filler, which is higher than that of unfilled epoxy material and the inclusions, eg. Moisture included on the interface of nanoparticles and inside agglomerates. On the other hand, lower permittivity of nanocomposite would be mainly attributed to the restriction of polymer chain movement in the specific interfacial region between nanoparticle and polymer and also by large interfacial area of nanoparticles with homogenous dispersibility [4].
Epoxy resin matrix used that was Nitofill, EPLV from Fosroc Company with Nitofill EPLV hardener. The mixing ratio is 3:1 gelling time 40 minutes at 35
0
C. The particle fillers are alumina nanoparticle by sigma-Aldrich chemistry.
Average particle size <50nm while density 4.000 g/cm
3
the purity of Al
2
O
3
nanoparticles is 99.9.
AFM was performed to measure the average diameter of Alumina nanoparticles by using AA3000 Scanning Probe
Microscope by: Angstrom Advanced Inc. USA. We found the average diameter 46.73nm agrees with data sheet of Al
2
O
3 table (1) and figure (1) shows the percentage and particle diameter of Al
2
O
3
nanoparticles.

International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014
Table (1): Diameter, volume (%), and Accumulation (%) of Al
2
O
3
nanoparticles
ISSN 2319 - 4847
Diameter(nm)< Volume(%) Cumulation(%) Diameter(nm)< Volume(%) Cumulation(%) Diameter(nm)< Volume(%) Cumulation(%)
38.00
40.00
42.00
44.00
0.78
15.69
10.98
10.59
0.78
16.47
27.45
38.04
46.00
48.00
50.00
52.00
11.76
8.24
11.37
9.02
49.80
58.04
69.41
78.43
54.00
56.00
58.00
60.00
6.67
3.92
8.63
2.35
85.10
89.02
97.65
100.00
Figure (1): percentage (%) vs. Diameter of Al
2
O
3
nanoparticles
There are many techniques which can be used to incorporate the nanoparticles into the polymer matrix. However, in this study we used two preparation methods.
The first method without nitrogen flow included: nanoparticles heating in an oven at 130
0
C to reduce the moisture, and then weighted. Nanoparticles with epoxy resin were mixed by magnetic stirrer at 700 rpm 60
0
C for 30 minutes, used the homogenizer devices 3 min for separate nanoparticles and broken up the agglomeration of its to improve compatibility of the filler with host material. The hardener was mixed for 10 minutes by magnetic stirrer, using homogenizer device for 3 min again to get better homogeneity. During the preparation, air bubbles can get trapped in the material, especially during the mixing processes. To negate the influence of air bubbles on mechanical and dielectrical measurements, degassing of the epoxy/Al
2
O
3
nanocomposites required so we used vacuum system (10
-2
bar) as shown in figure (2) to remove the bubbles before molding the composites.
Figure (2) Vacuum system used to remove the bubbles from the samples

International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014 ISSN 2319 - 4847
We found the shape of specimen for concentration 0.1% wt. of Al
2
O
3
nanoparticles is not perfect because it is contains some intended matter that is come from atmosphere as shown in figure (3a).
The second method with nitrogen flow included: after heating the nanoparticles in an oven as in the first method, the nanoparticles are weighted and manually mixed with epoxy resin under gloves in nitrogen atmosphere which is shown in figure (4). Then followed the same procedure of the first method, we found the shape of specimen for concentration 0.1% of Al
2
O
3
nanoparticles is very perfect and do not contain on any intended matter [5,6] as shown in figure (3b).
Figure (3-9) shape of specimen for methods a) without nitrogen flow included b) with nitrogen flow included
Figure (4) Gloves box (handmade by researcher
The second preparation method is preferred because it is not very complicated from laboratory processing point of view, commercially available polymers and particles could be mixed with ease to prepare a composite, and it's not contain on air bubbles, dust or other unintended matter in polymer matrix can act as defects, which in turn can significantly influence on the mechanical and dielectrical properties of EP/Al
2
O
3
nanocomposites So, we used the final preparation method for preparation the specimens and then tested it.
For understanding of possible interaction between nanoparticles and the epoxy, the surface chemistry of nanoparticles and the chemical nature of the cured epoxy system are characterized through Fourier transform spectroscopy (FTIR) measurements using FT-ic88735 device.
The dielectric spectroscopy measurement is the method to measure the materials’ dielectric properties as a function of frequency. The applied electric filed and temperature also can be variables in the measurements. The dielectric spectroscopy is based upon the interaction of the electric dipole moments within the sample and the applied filed, and provides the dielectric properties of materials, such as relative permittivity and loss factor. By testing the sample’s

International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014 ISSN 2319 - 4847 dielectric properties, the information about mobility of polymers can be provided. A computerized sensitive impedance analyzer type (Avcitive Awia, Agilent 4294A) was used to perform the dielectric spectroscopy measurement.
The device range of frequency 40Hz – 110MHz, and electrode diameter 1.25 cm. The dielectric properties (relative permittivity; real part of dielectric constant and tan delta) of the epoxy and epoxy nanocomposites are tested over the frequency range 10
3
- 10
6
Hz. The permittivity and tan delta were measured at room temperature; the applied voltage was
500 mV. All the samples were prepared and measured over a period of 45 days. The numbers of measurement points were 201 for each test for above frequency range.
The shape of the mold was used for dielectric test is shown in figure (5). The samples shape prepared for dielectrical test identical to the specification of ASTM (D150) as in figure (6A and 6B).
Figure (5) Mold of the samples for dielectric test
Fig. (6 A). Epoxy nanocomposite specimen shape for dielectrical test where; (R) is the diameter of the sample, ( d ) is specimen thickness.
Figure (6B): Epoxy nanocomposite specimens shape prepared for dielectrical test.

International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014 ISSN 2319 - 4847
For Fourier Transform Spectroscopy (FTIR) measurements the samples were scanned in absorption mode in the range of wave length 4000-400 cm
-1
. nanoparticles are dried at temperature of 100 o
C for 12h or more and kept under vacuum after which pellets pressed with potassium bromide (KBr) solution are prepared for FTIR measurements. When preparing the pellets using KBr, care was taken to ensure that the moisture does not get into the sample. For the nanocomposite sample, they are kept under vacuum evacuation for more than 12h (immediately after preparation) before they are used for the FTIR measurement. Only during the measurements, the samples get exposed to moisture if any and the time duration for experiments is too small for moisture to get absorbed into the sample.
The dielectric properties (relative permittivity (real part) and tan delta) of epoxy/Al
2
O
3 the frequency range 10
3
-10 nanocomposite are tested over
6
Hz. The permittivity and tan delta were measured at room temperature; the applied voltage was 500 mV. The data presented in this paper for all measurements are an average value of three samples the variation of the dielectric constant with frequency is similar to the variation of polarizability and polarization. At low frequencies of the order of a few Hz, the dielectric constant is made up of contributions from electronic, atomic and space charge polarization.
When measurements are carried out as a function of frequency, the space charge polarization ceases after a certain frequency and the dielectric constant becomes frequency independent. The frequency beyond which the variation ceases may fall in the certain range. The frequency-independent value is taken as the true static dielectric constant [7].
By measuring the dielectric constant as a function of frequency, one can separate the various polarization components.
Each polarization mechanism has a limiting characteristic frequency. Electrons have very small mass and are therefore able to follow high frequency fields up through the optical range. Ions are a thousand times heavier but continue to follow fields up to the infrared range. Molecules—especially those in liquids and solids—are heavier yet and are severely impeded by their surroundings. Most rotational effects, like those in water, are limited to microwave frequencies. Space charge effects are often in the kilohertz range or even lower Frequency has an important effect on the polarization mechanisms of a dielectric. When the frequency of the applied field is quite large as compared to the inverse of the relaxation time for a particular polarization process, the contribution of that process to the polarizability is negligible. As relaxation time is maximum for the dipolar process, The dipolar contribution disappears first followed by ionic and electronic contributions. Figure (7) shows a typical frequency spectrum of a dielectric containing all four types of polarization [8, 9].
Figure (7): the frequency dependence of polarizability showing several contribution mechanisms [8]
Literature cites that polymer nano-composites have tendency to absorb more moisture significantly and this absorb moisture can have a strong influence on the thermal and dielectric characteristics of these materials [10]. Therefore, as a general perquisite for all the experiments, nanocomposite samples were prepared at least 48h prior to the experiments and they are kept under evacuation before they are used for the measurements.
The FTIR measurements were done for unfilled epoxy, epoxy-Al
2
O
3
nanocomposite and Al
2
O
3
nanoparticles. The
FTIR spectra for unfilled epoxy system and an epoxy-Al
2
O
3
nanocomposite are shown in figure (8 a and b), respectively, whereas the details of functional groups associated with FTIR plots are given in table (2). It is clear from the FTIR plots

International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014 ISSN 2319 - 4847 that the introduction of Al
2
O
3
nanoparticles into epoxy does not result in the formation of new bonds. But, the interface model predicts that there is an occurrence of marginally strong bonding between the nanoparticle surface and the epoxy chains at the first interfacial nanolayer. Hence, there has to be some sort of interaction happening in that region. In order to get further insights, the surface chemistry of Al
2
O
3
nanoparticles is also examined through FTIR spectroscopy and the spectrum is shown in figure (8 c). the spectrum of nanoparticles shows the occurrence of two prominent peaks which are relevant for the present analysis-one centered around 3461cm
-1
and the other around 1634cm
-1
. The peak at 3461cm
-
1 corresponds to the vibration of hydroxyl (OH) groups which shows that OH groups are present on the nanoparticle surface. The OH groups are present on the nanoparticle as free OH groups attached to absorbed water molecules or both.
Water molecules can get absorbed on the surface of nanoparticles due to the affinity of H
2
O molecules (polar in nature) present in atmosphere to involve in hydrogen bonding with surface OH groups on the nanoparticles. The presence of absorbed water molecule on the nanoparticle surface is also reflected from the fact that there is a small peak at 1634cm
-1 on the FTIR plot that corresponds to the bending vibration of water molecules. These results from the FTIR studies indicate that there are surface OH groups can indulge in hydrogen bonding with polar molecules this behavior which agree with Costa et.al.[11] and Abedini[12].
Now, the epoxy base resin is also polar in nature and contains two epoxide groups at both the ends, and an epoxide group is dipole on its own with pairs of electrons on the oxygen. As per the epoxy nanocomposite preparation methodology used to prepare the samples, the fillers are first mixed to the resin followed by addition hardener to the resin-particle mix to initiate the curing process. When hardener is added to the resin-particle mix, the epoxide group opens up and these groups can also form hydrogen bonds with free OH groups on the nanoparticle surface in addition in reacting with amine groups of hardener.
Table (2): FTIR Peaks Corresponding to functional Groups in Epoxy system [13].
Wave number (cm-1) Functional Groups
~3461
~3035
OH groups
Corresponds to the C-H stretch in aromatics
~2969
~2929
Corresponds to asymmetrical C-H stretch of -CH3 group
Corresponds to asymmetrical C-H stretch of –CH2 group
Corresponds to C-C stretching vibration in aromatic ~1618
~1585
~1511
~1463
~1296
~1251
~1183
~1038
~914
~830
Corresponds to asymmetrical-CH2 deformation
Corresponds to asymmetrical aromatic C-O stretch
Corresponds to asymmetrical aliphatic C-O stretch
Corresponds to asymmetrical aromatic C-O
Corresponds to epoxide ring vibrations
Corresponds to –CH out of plane deformation in aromatic
Because of the abundance of free OH groups on the nanoparticle surface, the density of hydrogen bonded epoxy segments will be high at the region just close to the nanoparticle surface. This process of formation of hydrogen bonds in the epoxy nanocomposite system explains formation two nanolayer; the tightly and strong nanolayer of epoxy segment at interface region with nanoparticles, this behavior in good agreement with Singha and Thomas [9].
Unfilled Epoxy

International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014
(a)
ISSN 2319 - 4847
Epoxy-Al
2
O
3
Nanocomposites
(b)
Al
2
O
3
Nanoparticles
(c)
Figure (8): FTIR spectra of materials under evaluation. (a) Unfilled epoxy system. (b) EP-Al
2
O
3
nanocomposite system. (c) Al
2
O
3
nanoparticles.
The variations of relative permittivity with respect to frequency range 10
3
-10
6
Hz at room temperature for EP and EP/
Al
2
O
3
nanocomposite with 1, 2, 3, 4, 5, and 7% wt. of Al
2
O
3
nanoparticles are shown in figure (9). It is known that the effective permittivity of EP and EP/ Al
2
O
3
nanocomposite is found to be governed by polarization associated with EP and
Al
2
O
3
nanoparticles and it is strongly influence by interfacial polarization at interface between epoxy and nanoparticle as well. Therefore, such a reduction in effective permittivity had been observed as frequency of measurement will influence the polarization processes. It is also known that in typical resin system, the permittivity of epoxy is determined by number of orientable dipoles with system and their ability to oreintable under applied electric field. Similarly, the increasing frequency of applied field will also result in reduction of Al
2
O
3
fillers inherent permittivity [1]. The combination of both effect results in the reduction of epoxy/nanocomposite permittivity with increasing frequency.

International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014
Figure (9) Real permittivity versus frequency for epoxy and EP/Al
2
O
3
nanocomposites.
ISSN 2319 - 4847
It also can be seen from graph that when the nanoparticle are added into the base epoxy (1% wt. of Al
2
O
3
nanoparticles), the resulting relative permittivity is lower than that of the unfilled epoxy resin. This reduction in relative permittivity attributed to reduction of mobility of the dipolar groups within the composite will reduce the polarization within the composites this behavior is in agreement with Andritch [11]. The interaction between nanosize filler and epoxy chain reduces the mobility of epoxy chain in bulk material, which will result in a decreasing of the effective permittivity of epoxy/Al
2
O
3
nanocomposites. When small amount of nanofiller is loaded into epoxy, due to the interaction between filler and epoxy chain, the thin immobile nanolayers can be formed. Those thin immobile nanolayers will restrict the mobility of epoxy chain [5]. So increasing the immobility epoxy chains by raising the weight percentage of nanoparticles will reduce the relative permittivity of EP/Al
2
O
3
nanocomposites. The influence of relative permittivity of Al
2
O
3
nanoparticles which is higher than that of epoxy will not be very effective and value of the relative permittivity of EP/Al
2
O
3 nanocomposites will be close to that of epoxy. The relative permittivity of EP/Al
2
O
3
nanocomposites at 2, 3, and 4% wt. of Al
2
O
3
nanoparticles increases because the influence of the relative permittivity of Al
2
O
3
nanoparticles in the relative permittivity of EP/Al
2
O
3
nanocomposites begin to appear in obvious manner. , this behavior is in a good agreement with
Singha and Thomas [10].
The relative permittivity of EP/Al
2
O
3
nanocomposites decreases again at 5 and 7% wt. of Al
2
O
3
nanoparticles. The influence of the overlapping of the interaction zone of nanoparticles and the percolation effect through the interaction zone reduce the relative permittivity of EP/Al
2
O
3
nanocomposites this behavior in good agreement with Wing [1].
2
3
The variation of tan delta with frequency for EP and EP/Al
2
O
3
nanocomposite with 1, 2, 3, 4, 5, and 7% wt. of Al
2
O
3 nanoparticles at room temperature are shown in figure (10). The measured temperature is maintained constant, so their influence on the relaxation time of charge carriers is neglected. For range of frequency between 10
3
-10
6
Hz the value of tanδ increase with increasing frequency up to 1 MHz and this increase is more to do with the frequency dielectric relaxation behavior associated with epoxy[5].
The electrical conduction of nanocomposite is one of parameters which contr ol the value of tanδ in material, the electrical conductivity, in turn, depends on the number of charge carriers, and the frequency of applied electric field.
The nature of bonding at interface region can also influence the electrical conduction processes in the bulk of nanocomposite Zhang et al. (14) had reported the presence of hydrogen bonds at the interface region in an epoxy nanocomposite causes enhancement in transport of charge carrier thereby, increasing in electrical conduction at interface.
At let as analysis how the presence of nanoparticles and the charge transport characteristics at interface region influence the electrical conduction mechanisms in bulk of nanocomposite.

International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014 ISSN 2319 - 4847
1) The presence of significant number of nanoparticles in the bulk of nanocomposite will act as barriers to flow of charge carriers.
2) There is an occurrence of hydrogen bonding at first nanolayer of interface as per dual nanolayer model. Therefore,
Considering Zhang [14] result, the first nanolayer of interface region in epoxy-Al
2
O
3
nanocomposite system cannot be assume to be electrically conductive region this is part from fact that the presence of stable strongly bonded first layer of interface (caused due to the hydrogen bonding) will reduce the probability of defects in this region which in turn causes a reduction in availability of free charge carriers.
3) As for the second nanolayer of the interface region, the presence of loose epoxy segments can result in contrasting characteristics. First, the region will allow the existence of free charge carriers (due to impurities). Second, the mobility of charge carriers will be higher in this region thus making the region electrically conductive. Third, because of the loose nature of epoxy material, there is also a high probability of defects to be present in this region that can act as sites for charge trapped
At lower nanofiller loading (1% wt. of Al
2
O
3
nanoparticles), the number of nanoparticles in the nanocomposite will be less, the inter-nanoparticle distances are higher and the interface region has a significant volume fraction of first and second nanolayers.
However, at higher filler nanofillers loadings (2,3,and 4% wt. of Al
2
O
3
nanoparticles), the number of nanoparticles is more, the inter-particle distances are less, the fraction of first nanolayer is higher and the fraction of second layer is lower due to the formation overlapping regions. Hence, the availability of free charge carriers from fillers is higher, free charge carrier contribution from second nanolayer is less, electrical conduction can take place easily due to the close proximity of interface regions and there will be a reduction in possibility of defects and charge trapping sites. In such situation the value of tanδ in nanocomposites will be enhanced as compared to unfilled epoxy, depending on the Nanofiller loadings.
However, this enhancement in conductivity will be countered by increase in the tortuousness of conducting path and also on actual availability of free charge carriers (stable bonding at first interface layer will reduce the availability of free electronic charge carries). This tussle between these two processes-one which enhances the conductivity while the other which tries to reduce it, is complex and difficult to comprehend with limited insight available at this time. Although the addition of nanofillers reduces the values of tanδ as compared to unfilled epoxy, between nanocomposite systems with different filler concentrations, the tanδ is marginally in the nanocomposites having higher filler loading. The addition of more nanoparticles (5 and 7% wt. of Al
2
O
3
nanoparticles), increases the source of charge carriers causes an increase in the tanδ value this behavior in good agreement with Wang [1].
Figure (10) Tan Delta value of Epoxy and epoxy/Al
2
O
3
nanocomposite with different concentration of Al
2
O
3
nanoparticle s

International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 3, Issue 1, January 2014 ISSN 2319 - 4847
Conclusions
1) Fourier transforms spectroscopy showed that there is hydroxyl group (OH) on the nanoparticles surface. This hydroxyl group form hydrogen bound with epoxide group. The process of formation of hydrogen bonds in the epoxy nanocomposite system explains the formation of the strongly bonded and tightly bond first nanolayer of epoxy segments at the interface region as per the dual nanolayer interface model.
2) The dielectric spectroscopy of epoxy/Al
2
O
3
nanocomposites are influenced by the nature and characteristics of the epoxy- nanoparticles interfaces. The interfacial interaction result in a lower permittivity (up to particular filler loading) and lower ta nδ values as compared to unfilled epoxy values. The permittivity reduction is probably due to constrain of polymer chain mobility whereas inhibition in charge carrier transport due to interfaces and chain entanglements result in lower Tan delta value.
1. Q. wang, "The Effect of Nanosized Filler on Electrical Performance of Epoxy Resin", Ph. D. Thesis, University of
Southampton, United of kingdom (2012).
2. S. Singha and M. J. Thomas, "Dielectric Properties of Epoxy Nanocomposite", IIE Transactions on Dielectrics and
Electrical Insulation vol.15, No.1 (2008).
3. I. Plesa, F. Ciuprina, and P. V. Notingher, "Dielectric Spectroscopy of Epoxy Resin with and without Inorganic
Nanofillers", Journal of advanced research in physics Vol. 1(1), 011011(2010).
4. M. Kurimoto, H. Okubo, K. Kato, M. Hanai, Y. Hoshinea, M. Takei and N. Hayakawa, "Nanocomposite with High
Particle Dispersibility by Combining Ultrasonic Wave and Centrifugal Force", Journal of Electrical Insulation
Conference, vol. 10, 1070-9878 (2010).
5. M. M. Abd, "(Nano_Micro) Particles/Epoxy Composites", Ph.D. Thesis, Department of Physics, Baghdad University,
Iraq (2012).
6. B. Bittmann, F. Haupert , and A. K. Schlarb, "Ultrasonic Dispersion of Inorganic Nanoparticles in Epoxy Resin",
Journal of Ultrasonic Sonochemistry, Elsevier vol. 16, 622-628 (2009) .
7. B. Tareev, "Physics of Dielectric Materials", Mir publisher, Moscow (1979).
8. P. S. Halasyamani & K.R. Poeppelmeier, "Noncentrosymmetric Oxides", Chem. Mater., vol. 10, 2753-2769 (1998).
9. S. Singha and M. J. Thomas, "Dielectric Properties of Epoxy-Al2O3 Nanocomposite System for Packing Application",
Journal of IEEE Transactions on Components and Packing Technology Vol. 33 No.2, 1521-3331(2009).
10. T. Andritsech, R. Kochetov, B. Cennom, peter H. F., Morshuis, and J. J. Smit, "Space Charge Behavior of
Magnesium Oxide Filled Epoxy Nanocomposites at Different Temperature and Electrical Field Strengths", Journal of
Electrical Insulation Conference, Maryland doi: 10.1109/ EIC.5996133 (2011).
11. T. M. H. Costa, M. R. Gallas, E. V. Benvenulti, and J. A. H. dajornada, "Study of Nanocrystalline ɣ - Al2O3 Preduced by High-Pressure Compacties," Journal of American Chemical Society, Vol. 103, 4278-4284 (1999).
12. A. Abedini, E. Sanio, F. Larki, A. Zakari, M. Noroozi and N. Soltani, " Room Temperature Radiolytic Synthesized
Cu@CuAlO2-Al2O3 Nanoparticles," International Journal of Molecular Science, vol.13, 11941-11953(2012).
13. J. Mu, M. Mo, Y. Du, P. Rosso, K. Friedrich, and H. Kuan, "Effect of Inorganic Nanoparticles on Mechanical
Property,Fracture Toughness and Toughening Mechanism of Two Epoxy Systems," Elsiever, Polymer vol.49, 3510-
3523(2008).
14. C. Zhang, R. Mason, and G. Stevens, "Preparation, Characterization and Dielectric Properties of Epoxy and
Polyethylene Nanocomposite", Journal of IEEJ Trans. Fundam. Mater. vol.126, no. 11 (2006).