In this paper, some theoretical attenuation  parameters was calculated for shields  made up of composite materials basis polymer (Epoxy )  with added materials (C,Ni,PbO,Bi) with different concentrations (10,20,30,40,50)wt% , where the effect of concentrations variation on the attenuation coefficients values , effective atomic number and shields density has been studying. The computer program code X-Com was used to calculate the attenuation parameter values at different energies (0.662,1.173,1.332)MeV .Results shows that there is a clear change in the values of these parameters with the change of concentration ratios

Ibrahim, Abdulraheem Dheyaa

Mkhaiber, Ahmed Fadhil

English

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Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.46, 2015  41  The Effect of the Concentration Chang of Reinforcing Materials on the Values of Some Theoretical Attenuation Parameters  Ahmed Fadhil Mkhaiber    and   Abdulraheem Dheyaa Ibrahim  Department of Physics – College of Education (Ibn Al-Haitham) – University of Baghdad, Iraq. Abstract:      In this paper, some theoretical attenuation  parameters was calculated for shields  made up of composite materials basis polymer (Epoxy )  with added materials (C,Ni,PbO,Bi) with different concentrations (10,20,30,40,50)wt% , where the effect of concentrations variation on the attenuation coefficients values , effective atomic number and shields density has been studying. The computer program code X-Com was used to calculate the attenuation parameter values at different energies (0.662,1.173,1.332)MeV .Results shows that there is a clear change in the values of these parameters with the change of concentration ratios. 1.Introduction  In general, shields used to reduce exposure to nuclear radiation and their secondary interactions with the material and to minimize the effects on human tissue [1]. There are many shielding materials designed against various harmful rays to the human body. The polymer based composites   such as polyethylene,  polystyrene and epoxy have been selected in the field of radiation protection[2].In the recent years, composite materials employed in the gamma-ray shielding and showed good efficiency in this field, Composite materials are multi-phase materials obtained by artificial combination of different materials, so as to attain properties that the individual components by themselves cannot attain [3]. Epoxy is a adhesive resin that is resistant against water and acids  and do not lose strength over time, and have a good thermal and mechanical properties[4]. Reinforcement materials played the important role to improve the matrix properties.  With the good choice of metallic fi llers, gamma rays shielded[5]. Therefore, in this study, we attempted to prepare and characterize the polymer based composite radiation shields using epoxy as a matrix and C,Ni,PbO and Bi metals as fillers. Then, the effect of fillers concentrations variation on some attenuation parameters was studied.  2.Theory 2.1Mass attenuation coefficient  Mass attenuation coefficient μ is one of the most important factors that describe the  gamma rays penetrate through the target material [6].It is a measure of the average number of interactions that occurs between incident photons and matter of unit mass per unit area[7]. It is the fundamental parameter to derive many other parameters such as effective atomic number, electron density and half-thickness[8]. Calculations of the mass attenuation coefficients of all investigated samples at the energy 0.661,1332 keV were performed using the XCOM program which can generate cross sections and attenuation coefficients for elements, compounds or mixtures in the energy range between 1 keV and 100 GeV in the form of total cross-sections and attenuation coefficients [9].  2.2 Volume fraction and Density of composite shields The volume fraction of the composite material is the important factors to be controlled [10], and can be calculated from the following equation [11]:  −+=mffV ρρψψ.11/1                                                                                                                                     (1) Where   ψ  : is the fraction weighted for reinforcement materials.           mf ρρ ,: Density of reinforcement and matrix material respectively. Vf : volume fraction. While the density of composite materials can be calculated from the following equation [12]: Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.46, 2015  42  ρ = V	 ∗ ρ	 + 1 − V	ρ                                                                                                                                     (2) Where  ρ : is the density of composite material.  2.3 Effective atomic number   In composite materials, the scattering and absorption of gamma radiation are related to the effective atomic number (Zeff ) and the effective electron density (Nel) [13]. The effective atomic number which is a very useful parameter for many fields of scientific, technological and engineering applications [14]. The effective atomic number of the different shield composites is based on the determination of total attenuation cross section for gamma-ray interaction and it can be commonly obtained by the relation [15]: Z =σσ                                                                                                                                                            (3)  Where σ and σ represent total atomic cross section and total electric cross section respectively. The Zeff in equation (3) it's for matrix material (epoxy polymer in this paper)  , and the total Zeff of composite material shield  calculated by the relation[16] :  Zeff = ∑ 	 !"                                                                                                                                                     (4)  Were Wi and Zi represent the weight percentage of each substance in Shield and the atomic number of each substance in the shield respectively.     3.Results and discussion The mass attenuation coefficient, effective atomic number and density for each shield were calculated. The effect of increasing the filler concentration in the composite on these parameters was studied. The relationship between mass attenuation coefficient and concentration of the fillers shows in figures (1,2,3,4)  . From this figures , the value of attenuation coefficients increase when the concentration increase .This refer that there is  an improvement in the behavior of the epoxy and the composites  properties  moving towards concentration properties. As well known, the absorbance of metal to radiation is higher than the polymer, thus, composite materials become suitable to use as a shields against gamma rays.     Figure (5) represents the relation between concentration and effective atomic number. We can see form this figure , the effective atomic number increase with increasing of filler concentration , and this lead to increase the attenuation coefficient .We can explain this as, when effective atomic number increase , the probability of interaction of gamma rays with the shield material via photoelectric effect and scattering and attenuation  will be high, as well as when the effective atomic number is law, the probability of penetrating gamma rays will be high and therefore have law  attenuation. Figure (6) shows the relation between filler concentration and shield density. It obvious from this figure that the shield density increases with with increasing of filler concentration and this lead also to increasing the attenuation coefficient. The low density of  the shield material will give rise to less attenuation than a high density , since the chances of an interaction between the radiation and the atoms of the shield are relatively lower.   Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.46, 2015  43  4.Conclusion     We can conclude that increasing the concentration of reinforcement materials in composite materials affect the attenuation parameters, and this leading to improve the properties of composite materials and make them suitable for use as shields in nuclear applications.    Advances in Physics Theories and Applications                                                                                                  www.iiste.org ISSN 2224-719X (Paper) ISSN 2225-0638 (Online) Vol.46, 2015  44  References: 1-Rahman,I,M. (2010). Calculation the number buildup factor of cylindrical samples for Brass ,Copper & lead ,7,3,p1146. 2-Garea,S.A, Sandu.T,Constantin,F. (2010). Characterization of novel epoxy composites based on hybrid inorganic / organic polyhedral oligomeric silsesquioxane , Int.J.Polym.Anal.Charact.15,119-128 . 3-Deborah. D. L. Chung. (2002). Composite material science and applications, functional material for modern technologies  , Springer-Verlag London Ltd. 4- Kline, D. E. J. (1960).  Dynamic mechanical properties of polymerized epoxy resins. J. Polym. Sci. 47(149): 237–249. 5- ALLEN R.T., EDWARDS S.C. (1987). The Repair of Concrete Structures , (Blackies, Glasgow and London,) . 6- Abdel-Rahma, M,A and Et al. (2000).  effect of sample thickness on the measured mass attenuation coefficients of some compounds and elements for 59.54,661.6 and 1332.5 keV gamma-rays , Nucl Instrum Methods Phys Res,447,432. 7- I. Akkurt and A. M. El-Khayatt. (2013). Effective atomic number and electron density of marble concrete",J Radioanal Nucl Chem, 295:633–638. 8- N. Chanthima, J. Kaewkhao. (2013). Investigation on radiation shielding parameters of bismuth borosilicate glass from 1 keV to 100 GeV , Annals of Nuclear Energy 55 (2013) 23–28. 9- M.E. Medhat and et al.(2014). Calculation of gamma-ray mass attenuation coefficients of some Egyptian soil samples using Monte Carlo methods", Radiation Effects & Defects in Solids, Vol. 169, No. 8, 706–714. 10- H.A.H.Al-Abdli. (2002). Development of High Polymer Matrix Composition ,Ph.D.Thesis, Department of Chemical Engineering- University of Technology. 11- L.Robert and P.E.Mott.(1996). Applied Strength of Materials ,  3ed edition,University      of, Dayton. 12- M.M.Schwartz. (1983). Composite Materials Handbook , McGraw Hill Higher    Education. 13- G.J. Hine. (1952). The effective atomic numbers of materials for various gamma interactions, Physics Review 85 (1952), 725–737. 14- D.F. Jackson and D.J. Hawkes. (1981).  X-ray attenuation coefficients of elements and mixtures, Physics Report 70 (1981),169–233. 15- Guru Prasad S et al. (1998).  Effective atomic numbers for photo absorption in alloys in the energy region of absorption edges. Rad  Phys Chem 53:449–453. 16- Nicholas Tsoulfanidis. (1995). measurement and detection of radiation. Second Edition , University of Missouri-Rolla.  The IISTE is a pioneer in the Open-Access hosting service and academic event management.  The aim of the firm is Accelerating Global Knowledge Sharing.  More information about the firm can be found on the homepage:  http://www.iiste.org  CALL FOR JOURNAL PAPERS There are more than 30 peer-reviewed academic journals hosted under the hosting platform.   Prospective authors of journals can find the submission instruction on the following page: http://www.iiste.org/journals/  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.  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The Effect of the Concentration Chang of Reinforcing Materials on the Values of Some Theoretical Attenuation Parameters

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The Effect of the Concentration Chang of Reinforcing Materials on the Values of Some Theoretical Attenuation Parameters

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