IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 D.C. Electrical P roperties of MgCl2–Filled PEO Films A.A. Salih Departme nt of Physics, College of Education - I bn Al-Haitham, Unive rsity of Baghdad Abstract The D.C. electrical p rop erties of p oly (ethy lene oxide)/M gCl2 comp osites were invest igated as a function of different M gCl2 filler concentrations (0, 5, 10, 15 and 20 wt .%) and different temp eratures in the range (276–333) o K at three different p olarizing fields. Resistivity :  and dc Conductivity : σ dc were measured, and the activation energy : Ea of the thermal rate-p rocess of the electrical conduction was invest igated. It was found that the current-voltage measurement results exhibited Ohmic resistance behavior, the comp osites exhibit negative temp erature reliance of resistivity and enhancement in the D.C. electrical conductivity with both temp erature and M gCl2 concentration. The determined activation energy was found to decrease with both app lied p olarizing fields and M gCl2 content. The observed overall mechanism of electrical conduction was discussed on the basis of mobility of PEO chains and to the transfer of electrons through the salt aggregations dist ributed in the p olymer matrix, and it was observed that all of the composites were found to be similar to the semiconducting behavior. Key words: DC Conductivity ; PEO; M gCl2; Activation energy . Introduction M aterials can be classified according to their electrical conduction into: conductor, semiconductor and Insulator; one of the most imp ortant advanced subject, namely conductive p olymer comp osites, was given a great interest in many industrial app lications and covering large area in different material uses owing to their desirable p rop erties which made them favorable comp ared to other commercial materials [1]. Conducive p olymer comp osites p ossess a wide range of electrical conductivity that covers several orders of magnitude extending from insulators up to semiconductors and sometimes to good conductors [1, 2]. Semiconducting p olymeric mixtures are becoming common in many app lications such as heating, p revention of st atic electricity accumulation, for examp le, p reventing dust att raction on Computer cabinets and electrodes [2, 3]. Poly mers in semiconducting/conducting region are used for electromagnetic interference shielding of electronic devices and p reventing of st atic electricity hazards in the handling of electronic chip s and exp losives [3]. Conductive p olymers are also used as sensors, heating elements and p articularly selflimiting electrical heaters, switching devices and op toelectronic app lications [4]. Electrets formed by thermal methods are referred to as thermoelectrets. It is well known that in general, thermally st imulated discharge conductivity from thermoelectrets is considered to be induced by the thermal release of dipoles, ions and trapp ed electrons [1, 5], and the conductivity of the comp osite is determined by the combined effect of three main mechanisms: (a) quantum tunneling or hop p ing of electrons t hrough a thin insulating film that can form on the surface of the conducting filler; (b) constriction of electron flow due to p article–particle contact resistance; and (c) intrinsic conduction of the filler [6]. There are two app roaches to make electrically conducting p olymer comp osites: (i) use of conductive (salt or carbon black fibers or p articulate fillers) in app rop riate lay up , doses and disp ersions in an insulating p olymer matrix to p roduce semiconducting or conducting reinforced or filled comp osites and (ii) use of an inherently conducting p olymer intimately IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 blended with or disp ersed in a second p olymer matrix (i.e. insulating in character) during or subsequent to sy nthesis [4, 7]. The p resent work belongs to category (i) and accounts for the exp erimental st udy relating to the behavior of d.c. electrical conductivity in insulating p olymer like PEO rendered semiconductive with filling of less amount of M gCl2 salt. Highly disp ersed activated salt, giving sufficient conductivity at comp aratively low concentrations، is used. The D.C. electrical conductivity and the temp erature effect on resistance were st udied as a function of M gCl2 concentration and temp erature using the current/voltage characteristics. M any kinds of conductive fillers have been used with insulating p olymers such as salt, carbon fibers, and metallic p owders. Inorganic salt is a material that has found widesp read use in a number of app lications; the p urp ose of adding M gCl2 filler is to imp rove the p hy sical p rop erties of p olymers, where M gCl2 with high st ructure has a high ability to form a continuous network in the polymer matrix and hence leads to higher conductivity [8, 9]. M any st udies have been reported on electrical and thermal prop erties of PEO-salt comp osites which might be useful in some advanced and industrial app lications [10, 11, and 12]. On the other hand, invest igation of the D.C. electrical p rop erties of these composite sy st ems is still limited. At the same time, to our knowledge, no research reported the effect of M gCl2 salt on t he D.C. electrical p rop erties of PEO p olymer [8,13], AYESH et al. [14]st udied the electrical p rop erties of PC/M nCl2 comp osite and they found that t he volume resistivity decreases with the increase of M nCl2 concentration while the D.C. conductivity is in the range of 10 -5 (ohm.m) –1 . These filled p olymers have a number of advantages in terms of (i)absorbing the sp ecific radiation, (ii)imp roving thermal st ability , (iii)enhancing thermal and electrical conductivities, and (iv)reducing the cost and easy p rocessability to achieve conductivity [15]. The st udy of resistivity and thermal noise of amorp hous p olymers (Poly ethy lene oxide, Poly ethy lene glycol) contains a small p ercentage of NaI which was reported by Dillip et al [16]. Time dependent resistivity was recorded in glass transition (Tg) and melting temp erature (Tm) regions. The thermally st imulated discharge current technique which is used to st udy the D.C. electrical conductivity p rop erties, p roved similarity between dipolar and sp ace charge relaxations and it is a basic tool to identify and evaluate the dipole reorientation p rocess, trapp ing and recombination levels in electrets [1, 17]. Experimental Fil ms preparation The resin used in this work is p oly (ethy lene oxide) resin (M W 4,000,000) was obtained from CNR (Nop oli-Italy ). Ordinarily, the salt M gCl2 was ground into fine powder by agate mortar and sieved by a U.S. st andard sieve of size (63 μm). Thin films of PEO/M gCl2 were p repared by dissolving PEO resin in methanol at 303 o K; the M gCl2 salt was also dissolved in methanol at the same temp erature. Both solutions were mixed together for one hour by using a magnetic st irrer until a homogenous solution is obtained. Then the mixture was cast into a st ainless-st eel ring resting on Teflon substrate and waiting for a few day s unt il the solvents have evap orated. Samp les of different concentrations were dried in vacuum oven at 313 o K for t wo day s. T he drying p rocess was rep eated until prepared membranes have fixed weight to ensure the removal of solvent traces and to ensure uniform thickness. Then after comp leting evap oration, the film was detached from ring surface. In this way , the films were p repared by solution evap oration technique (cast ing method). The same p rocedure was used in the researches [8, 11, 13, and 14]. (PEO + M gCl2 ) , were prepared in the laboratory by weight p ercent method with an accuracy of 0.0001 g. Electronic single p an balance, Adiardutt -180. The prepared films contain 0, 5, IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 10, 15 and 20 wt % M gCl2. The film thickness (~0.15 mm) was measured using a ballended micrometer. Electrode coating For good ohmic contact, both the surfaces of film were coated by quick dry ing and highly conductive Silver p aint (Ernest F. Fullam Inc., Latham, NY) was app lied to contact p oints in order to reduce the resistance between the electrodes and the sample surfaces. Electrets preparation The exp eriments were done in winter, cause decrease in temp eratures. The coated film was sandwiched between the two copp er electrodes shielded cell, and the app lied p ressure to hold the test sp ecimen was exerted by top and bottom electrodes. The sample holder forming metal-p olymer-metal sy st em was p laced in a furnace and heated up to the 340°K. The sample was allowed to remain at that t emp erature for about 30 min. Then electric field of desired st rength was app lied for 1 hour at this temp erature with the app lied electric field. The sample was allowed to cool down to 276 o K in the p resence of app lied field. Total time of p olarization was adjust ed to be 2 hour in each case. On attaining 276 o K, t he samp les were kept short ed for 20 min to eliminate the st ray charges. The electrets were p repared at different D.C. p olarizing fields: E = 300 V/cm, 700 V/cm, 1100 V/cm, resp ectively. The D.C. Electrical Conductivity Measurement Aft er electrets formation, the test sample holder assembly was p laced in a controlled temp erature furnace. The D.C. electrical conductivity was measured by determining the resistance of a sample within temp erature range 276-333 °K at the rate of 2°/min. The temp erature was recorded by a digital thermometer having an accuracy of ±1°C. The electrical input was p rovided by means of a st abilized D.C. p ower source, and the current p assing through the sp ecimen was measured by a digital multimeter (M odel 3458A, Hewlett- Packard, Houston, TX). A digital multimeter (sy st ronics, 435) having an accuracy of ± 1 mV was used for the measurement of voltage drop across high resistance. The current and temp erature were monitored continuously during measurements. The method used for conductivity measurement was the same as that rep orted earlier with Shingo et al [18] and the sketch for the setup and the electrical circuit diagram used in the D.C. measurements was recently reported [19]. Not e that the volume resistivity ρ v was determined from the well-known relation equation [20]: )1.......(.......... vv R A    Where (Rv) is the volume resistance between the guarded and the bottom electrodes, which was measured directly by obtaining the current-voltage characterist ics of the cell; (A) is the disc area of the electrodes of radius 0.5 cm; and ( ) is the average thickness of the sample (~0.15mm). Re sults and Discussion The results of the p resent st udy are in the form of thermograms {Figures 1–2–3} which are curves between log of thermally st imulated discharge conductivity , log (σdc) and temp erature (10 3 /T) of the sample films at different p olarizing fields. Where, a significant curvature is quite p ronounced, this curvature has been frequently observed in many amorp hous p olymer comp osites sy st ems [21]. The thermograms of Figure 1 are of p ure PEO film. For all p olarizing fields, the D.C. conductivity is in insulating order. Figures 2 and 3 show that the PEO was rendered semiconductive by the addition of 0.05 and 0.20 weight p ercent of M gCl2 . The slight decrease is observed at low temp erature and continuous increase is observed up to 330°K in IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 all the samples. A nonlinear field dependence is clearly evident in p ure and filled PEO samples. The constituent of p ure film, viz. PEO, is largely an amorp hous p olymer. It is characterized by three relaxations: β relaxations occurring at low temp erature, α relaxation around the glass rubber transition temp erature (Tg) and α1 relaxation occurring at a temp erature well above (Tg) [22,23] . The absence of p eaks in the present t hermograms might be due to low app lied electric field [17]. In p olymeric materials, various ty p es of molecular relaxations are possible. The only motions p ossible at a low temp erature are local motions of molecular group s, e.g. rotation of side group s or internal motion within the side group s. Hence, at low temp erature there may be slight decrease and then rise in conductivity of thermoelectric of p ure PEO films. T his is due to mobility of main chain segment increase with the increase in temp erature [6, 8]. Figures 2 and 3 represent thermograms (log σdc vs. 10 3 /T p lot) of 0.05 and 0.20 weight p ercent M gCl2 salt added PEO thin film thermoelectrets for different p olarizing fields (300V/cm, 700V/cm, 1100V/cm). In both of the cases, the conductivity increases with increasing temp erature i.e. semiconducting nature of thermoelectric. Our exp erimental st udy revealed that electrical conductivity increases with the increase in temperature ap p roximately by the following equation [24]: σ = σ0 exp (–Ea/RT) …………….. (2), Where σ is conductivity , σ0 the p re-exp onential factor, Ea the activation energy of conduction and R the universal gas constant. The activation energy , Ea, was calculated from the graph of log σdc vs. 10 3 /T p lot. Tables 1–3 show the variation of activation energy values within low, intermediate and high temp erature regions. Addition of M gCl2 increases the conductivity of p olymer considerably {Figures 2 and 3}. As the p ercentage of loading is only 0.05 weight p ercent in second case, smooth increase was observed. Initially increase in conductivity at low t emp erature may be due to the injection of charge carriers directly from the electrodes [25, 26]. The filler is very sensitive to temp erature. There are two p hases i.e. p olymer p hase and filler p hase. They formed heterocharges and discharge by dipole disorientation is thermally activated and so can be sp eeded up by heating. The increase in conductivity at higher temp erature may be due to soft ening, the injected charge carrier can move more easily into the volume of the sample giving rise to a large current and increase in conductivity at higher temperature [6, 25]. In the third case, as shown in thermogram 3, the loading of M gCl2 Salt is slightly increased from 0.05–0.20 weight p ercent. There is a slight change in conductivity ,(σdc) for these samples esp ecially at higher temperature above Tg. As the temp erature increases, the chain of the PEO becomes more and more flexible [1]. This conduction is mainly due to a direct contact with Salt p article as exp lained by Tawansi et al and Saq’an et al [8, 11]. It is very clear at the first Figures {1–2–3}, the D.C. conductivity increases with t he increase of both electrical field and temp erature. The increase in conductivity with temp erature at a sensitively low field is due to the increase in the magnitude of the main free p ath of p honon [8, 25]. At high temp erature enhancement in conductivity is mainly att ributed to the increase in ionic mobility of M gCl2 Salt p articles [24]. Our results are in a good agreement with Tawansi et al [8], Jovic´ et al [6] and Ramadin et al [27]. The activation energy decreases significantly on the increase of the D.C. electrical field at room temp erature as shown in Figure 4 for different M gCl2 Concentrations, to emp hasize the p ossible effects of D.C. electrical field value. The field dependence of D.C. conductivity , σdc of the comp osites 5%wt M gCl2 and Pure PEO is similar. In both cases, t he conductivity increases sharp ly with increasing electric field. However, as mentioned above, both curves are much more sensitive to electrical filed than that 20wt .% M gCl2 sample is IBN AL- HAITHAM J. FO R PURE & APPL. SC I VO L.22 (4) 2009 almost unaffected by increasing the electrical field. This can be p robably ascribed to the enhanced electron scatt ering at filler contacts due to an increase in their kinetic energy as the electric field increases [6, 28]. For solid-state D.C. current-Voltage (I–V) measurements of PEO/M gCl2 comp osite, Figure 5 represent the D.C. voltage/current characterist ics at different temp eratures for the 5 wt .% M gCl2 comp osite, and exhibits a linear relation indicating ohmic behavior of the materials, which is consistent with electronic conduction [4]. The D.C. conductivity was evaluated to be 1.7×10 -5 S/m. The enhancement in the conductivity is by app roximately two orders of magnitude comp ared to the pure PEO and there is a small change in the conductivity with temp erature. It was observed earlier that the PEO-M gCl2 comp osite showed very low resistance and the enhancement were att ributed to inter p article tunneling [20]. Figure 6 shows the variation of the Resistivity (ρv) with M gCl2 salt concentrations. At lower concentrations -below 10 wt %- it was observed that the electrical resistivity decreases sharp ly; at higher salt concentrations, the resistivity decreases slightly where the comp osite becomes a good conductive substance at salt contents higher than 20wt % . This transformation from an insulating material to conductive one is due to the semiconductive M gCl2 salt and the generated electrical contacts resulting from the salt networks [18]. Figure 7 represents the D.C. electrical resistivity as a function of temp erature for comp osites with different M gCl2 salt concentrations. It was found that, at low salt concentrations (0, 5 and 10 wt %), the resistivity of samples is high and decreases sharp ly with increasing temp erature, which indicates that the D.C. electrical resistivity varies similar to a semiconducing behavior. The observed behavior in the D.C. electrical resistivity with M gCl2 salt concentration is att ributed to the p ercolation theory, where p olymer/conducting- filler comp osites exhibit a sudden transition from insulator to conductor at a certain filler concentration less t han 10 wt% M gCl2. This sudden transition in the comp osite resist ivity is a characterist ic of p ercolation threshold [21, 29]. At high salt concentrations over than 15wt.% M gCl2, the resistivity decreases slightly and slowly over the testing temp erature range, This result indicates a metallic-ty p e conduction mechanism due to conductive networks of Salt, where the thermal exp ansion effects cause a reduction in electrical contacts between the salt p article networks and hence result in a slowly decreasing resistivity of the comp osite with temp erature [30], or this slight decrease in resistivity may be due to the sp ace charge effect caused by the addition of Salt [25]. All tested comp osites of different M gCl2 concentration showed negative temperature coefficient of resist ivity . Figure 8 shows the variation of the DC-conductivity (σdc) with temp eratures for different salt concentration in the PEO/M gCl2 comp osite. It was observed that the D.C. conductivity increases with the increase of both temp erature and M gCl2 concentration. The increment in temp erature p rovides an increase in free volume and segmental mobility [15, 31]. These two entities then permits free charges to hop from one site to another thus increase conductivity . The conductivity increases so as temp erature indicates more ions gained kinetic energy via thermally activated hop p ing of charge carriers between trapp ed sites, which is temp erature dependence [32]. The observed increase of D.C. conductivity between 300 to 340 o K can be att ributed to large heat energy absorbed by the samp les and thus induce mobility of electrons [32]. It is suggested that in this region, the band gap between valence band and conduction band is reduced significantly and p rovide easiness for electrons to hop p ing from valence band to conduction band [1, 33] and hence gives higher D.C. conductivity values as comp ared to other temp eratures., i.e. The conductivity of the p olymer/Salt comp osites st rongly depends on the p articles’ interfacial resistance, which has two major contributions: ‘‘contact resistance” and a so-called ‘‘tunneling resistance”. The former dominates in highly filled comp osites, when p hy sical contact between the particles is p resent, while the latter is IBN AL- HAITHAM J . FO R PURE & APPL. SC I VO L.22 (4) 2009 related to the p resence of an insulating p olymer film on the p article surfaces. Tunneling is a transp ort p rocess that depends on thermal fluctuations [34], and a temp erature increase will reduce ‘‘tunneling resistance”, i.e. give rise to conductivity [6, 35], it is p robably the result of the sep aration of the p articles due to the soft ening of the PEO matrix. It app ears, however, that the ‘‘tunneling conduction” can comp ensate for the lack of p article contacts because at higher temperatures the energy barrier tends t o be lower [34]. Figure 9 represents Logarithm of resistivity {Log (ρv)} against reciprocal absolute temp erature, or what is called the Arrhenius exp onential law equation (15, 36). The activation energy Ea is calculated from the slop e of the best fit of t he exp erimental Arrhenius curves as ap p roximate st raight lines by using the equation: ρv = /σ………(3) Where ρv is the measured resistivity and σ is conductivity which is shown in equation [2]. The conduction activation energy of the conductivity influenced by temp erature is the minimum energy required to overcome potential barrier in the composite sy st em. The activation energies for the comp osites calculated from Figure 9 are shown in Table 4 with average error (±0.027), the dependence of the app arent activation energy of the electrical thermal activated rate-p rocess on the M gCl2 salt concentration is represented in Figure 10. The figure shows that the activation energy decreases rapidly with the increase of the M gCl2 salt concentration of comp osites. This behavior of the activation energy with temp erature is similar to most conductive p olymer comp osites with Salt content [8, 11, 12, 18, 19, 37, 38], a case which reflects that a new conductive p olymer comp osite is constructed from the insulating p olymer PEO. Finally, it is wort h mentioning that our calculated value of the activation energy is about 64 kcal.mol -1 for p ure PEO, and it is very close to the value of 65 kcal.mol -1 as recently reported in [39]. Conclusion A study of the effects of t he filler salt concentration and temp erature on the volume D.C. conductivity of PEO/M gCl2 comp osite is p resented in this article. The volume resistivity behavior and the concentration of salt p rop erties of this comp osite are invest igated at temp eratures ranging from (276 to 333) o K. From the obtained results, the following conclusions are drowning: 1. Both the temp erature and addition of M gCl2 Salt concentration influence the D.C- conductivity of PEO; this filled PEO p olymer could be good for low cost semiconducting comp osites. 2. The increase in temperature (above Tg) would lead to t he increase in D.C. conductivity , and the increase in the electrical field would lead to a decrease in the activation energy . 3. The resistance of the PEO/M gCl2 comp osites was found t o be Ohmic, and the temperature coefficient of resistance is negative. 4. The overall dependence of the D.C. electrical conductivity of the PEO-M gCl2 comp osites on temp erature was found to be similar to t he semiconducting behavior. 5. The temp erature dependence of D.C. conductivity for the given comp osites is st rongly influenced by the conductivity behavior of the M gCl2 concentrations. 6. The overall conduction mechanism is related to electrons transfer through the M gCl2 aggregations dist ributed in the p olymeric matrix. 7. The increase in both of temp erature and M gCl2 concentration would lead to a clear decrease in the activation energies of t he composites. 8. The thermoelectrically conduction behavior of the comp osites is interp reted in the form of variable range hop p ing mechanism and on the basis of mobility of PEO chains and to t he transfer of electrons through the salt aggregations dist ributed in the p olymer matrix. IBN AL- HAITHAM J . FO R PURE & APPL. SC I VO L.22 (4) 2009 Re ferences 1- Seanor, D. (1977), Electrical Prop erties of Poly mers, Cambridge University Press, London. 2- Narikes, M .; Rami, A. and Flashwiner, F. (1978), Poly mer engineering and science, 18: 649–653. 3- Krochwitz, J. I., (1998), Electrical and Electronic p rop erties of p olymer, 1 st edition. John Wiley & Sons. Inc., London . 4- Norman, R.H. (1970), Conductive rubbers and p last ics, Ap p lied Sciences Pub, London. 5- Rajesh Kalia; Sunil Kumar ; Bhatt i, H. S. and Sharma, J. 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(2000) Semiconducting and Poly meric M aterials: The Fourth Generation of Poly meric M aterials. Nobel Lecture. IBN AL- HAITHAM J . FO R PURE & APPL. SC I VO L.22 (4) 2009 34- Shang, P.; Sichal, E. and Gitleman, JL. (1978), Phy s. Rev. Lett. , 40(18): 1197-1208. 35- Giang Truong Pham, (2008), Characterization and M odeling of Piezo-Resist ive p rop erties of Carbon nanotube-based conductive Poly mer Composites, Ph.D. Thesis, Florida State University , (USA). 36- Bruce, H.andWarfield, R. (1986), Journal of Poly mer Science, 24: 877–883. 37- Elimat, Z. M . (2005) Electrical and Thermal Prop erties of Conducting Poly mer Composites, Ph.D Thesis, Phy sics Dep artement, University of Jordan, Jordan. 38- M att hew, L. C. (1998), Develop ment and M odelling of electrically conductive comp osite materials, Ph.D T hesis, Bachelor of science, M ichigan Technological University , (USA). 39- El̇ zbieta Zero, Henry k Wycí slik & M aciej Siekierski (2001), J. New M at.Electrochemical Sy st ems, 4: 143–148. Table (1): Variati on of activation ene rgy, Ea, in the three temperature regions for pure PEO thi n film. Polarizing field (V/cm) Ea (kcal. mo l -1 ) Ea (kcal. mo l -1 ) Ea (kcal. mo l -1 ) 300 59.3425 63.9917 68.7786 700 45.7856 49.9293 53.9987 1100 39.5662 43.2245 40.6322 Table (2): Variati on of activation ene rgy, Ea, in the three temperature regions for 5wt. %MgCl2 doped PEO Polarizing field (V/cm) Ea (kcal. mo l -1 ) Ea (kcal. mo l -1 ) Ea (kcal. mo l -1 ) 300 35.5623 43.9928 49.1129 700 26.7783 33.1255 39.3335 1100 21.2257 24.6503 28.9664 Table (3): Variati on of activation ene rgy, Ea, in the three temperature regions for 20wt %MgCl2 doped PEO Polarizing field (V/cm) Ea (kcal. mo l -1 ) Ea (kcal. mo l -1 ) Ea (kcal. mo l -1 ) 300 5.9753 6.2403 4.5465 700 1.1411 2.2595 2.0042 1100 0.2566 1.4177 2.4571 . Table (4): The Variati on of the activation ene rgy with MgCl2 concentration. Samp le Activation Energy , Ea (kcal. mol -1 ) PEO (Pure) 63.99178 PEO + 5 wt .% M gCl2 43.99282 PEO + 10 wt .% M gCl2 17.46373 PEO + 15 wt .% M gCl2 8.674247 PEO + 20 wt .% M gCl2 6.24029 IBN AL- HAITHAM J. FO R PURE & APPL. SC I. VOL. 22 (4 ) 2009 Fi g. (1 ): Natu ral Logari thm of DC-C ondu cti vi ty vs. 1000/T for Pure PEO . (at di ffe ren t d.c. pol arizing fiel ds) Fi g. (2 ): Natural Logari thm of DC-C on du cti vi ty vs. 1000/T for 5wt.% MgCl2 (at di ffe ren t d.c. pola rizing fiel ds) IBN AL- HAITHAM J. FO R PURE & APPL. SC I. VOL. 22 (4 ) 2009 Fi g. (4 ): Variation of the acti vati on ene rgy wi th DC -fiel d (for di fferen t MgCl2 Fi g. (5 ): V–I ch aracte risti cs fo r the 5wt.% MgCl 2 com posite. Fi g. (3): Natu ral Logari thm DC-C on du cti vi ty vs. 1000/T for 20wt.% MgCl2 (at di ffe ren t d.c. pola rizing fiel ds) IBN AL- HAITHAM J. FO R PURE & APPL. SC I. VOL. 22 (4 ) 2009 Fig. (8): Th e DC-Conductivity as a function of Temperature. Fi g. (6 ): Volume El e ctri ce Resisti vi ty as a function of MgCl2 Fig. (7): The Volum e Electrical R esisti vity as a f unctio n of tempera ture. IBN AL- HAITHAM J. FO R PURE & APPL. SC I. VOL. 22 (4 ) 2009 Fig. (10): Variation of the activation energy with the MgCl2 Concentration. Fig. (9): Th e Volume Electrical Resistivity Natural Logarithm versus the Reciprocal Temperature. 2009) 4(22مجلة ابن الھیثم للعلوم الصرفة والتطبیقیة المجلد الخواص الكھربائیة المستمرة لألغشیة المتكونة من بولي أوكسید اإلثیلین مع الملح كلورید المغنسیوم أیاد أحمد صالح جامعة بغداد ، إبن الھیثم -كلیة التربیة ، قسم الفیزیاء خالصةال قالبــاً وملــح ) بـولي أوكــسید اإلثیلـین(تـم فــي هـذا البحــث دراســة الخـصائص الكهربائیــة المـستمرة لمتراكــب مــن تعاملـــت هـــذه الدراســـة مـــع % ). 20إلـــى % 0( حـــشوة ذا تراكیـــز مختلفـــة داخـــل القالـــب بالمـــدى ) كلوریــد المغنـــسیوم( ) درجـة كلفـن333 درجـة كلفـن إلـى 276(راكیـز الملـح و درجـة الحـرارة بالمـدى التوصیلیةالكهربائیةالمستمرة للمتراكب دالـة لت . وضمن ثالث مدیات من مجال األستقطاب المسلط على العینة ُلقـد وجـد مـن . ُلقد حسبت المقاومة الكهربائیة النوعیة و قیست التوصیلیة الكهربائیـة المـستمرة وكـذلك طاقـة التنـشیط الحراریـة وكـذلك المتراكـب یبـدي مقاومـة كهربائیـة عكـسیة مـع زیـادة ، فولت تبـدي سـلوك مقاومةأومیـة- قیاسات تیارالنتائج أن نتاتج وتــنخفض طاقـة التنــشیط . وأن زیــادة كـل مــن درجـة الحــرارة وتركیـز الملــح تزیـد التوصــیلیةالكهربائیة المـستمرة، درجـة الحـرارة ویعــزى تفـسیر معظــم هــذه . مــع زیـادة كــل مــن مجـال األســتقطاب الكهربــائي المـسلط و تركیــز الملــح فـي المتراكــب الفعالـة و قـد ، الظواهر إلى قواعد حركة سالسل المبلمر و إلى أنتقال األلكترونات بین تجمعـات كتـل الملـح المنتـشرة فـي قالـب العینـة .الكهربائیة به موصلةأظهرت جمیع العینات سلوك مشابه لسلوك المواد الش .طاقة التنشیط الفعالة، الملح كلورید المغنسیوم، المبلمر بولي أوكسید اإلثیلین، التوصیلیة الكهربائیة المستمرة:الكلمات المفتاحیة