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Synthesis, characterization, thermal stability and DC conductivity of Polyaniline / Polyphenylene Sulfide Nanocomposites

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https://www.eduzhai.net International Journal of Composite M aterials 2013, 3(5): 115-121 DOI: 10.5923/j.cmaterials.20130305.01 Synthesis, Characterization, Thermal Stability and D.C. Electrical Conductivity of Pani/Pbs Nanocomposite J. B. Bhaiswar1,*, M. Y. Salunkhe 2, S. P. Dongre 3 1Department of Physics, Nagpur institute of Technology, Nagpur 2Department of Physics, Institute of Science, R.T. road, civil line, Nagpur 3Department of Physics, Bhalerao Science College, Saoner, Nagpur Abstract Nanocomposite of conducting polyaniline with PbS nanoparticles have bee n synthesized via in situ by oxidizing technique. The effect of PbS nanoparticles on the electrica l conductivity and Therma l Stability of polyaniline was discussed. The prepared products were characterized by FT -IR, XRD, Transmission electron Microscopy and TGA-DTA. FTIR absorption band at 415 cm-1 confirmed the concentration of PbS in polyaniline are low. TEM showed the PAni/PbS nanocomposite is in the nanorange.UV-Vs ible spectra of PAni/PbS nanocomposite shows the different absorption wavelength. The TGA/DTA thermogram shows increased in thermal stability as co mpare the pure PAni. The D.C electrical conductivity of polyaniline/PbS nanocomposite increased at (25%) wt (1.66x10-3S/cm) as compared to the pure polyaniline (10-10 S/cm), and Silicon (10-4S/cm) se miconductors. Keywords Polyaniline, Thermal, Electrical 1. Introduction The nanocomposites of metal and semiconductor particles have several therma l, optica l and electronics applications [1]. Org an ic– ino rg an ic n an oco mpos ite wit h an o rg an ized structure has been extensively studied because they combine the advantages of the inorganic materials, like (mechanical strength, electrical and magnetic p roperties and thermal st ab ilit y ) and t he o rg an ic p o ly mers like (Flexib ilit y , dielectric, ductility and processibility), which are difficult to obtain fro m individual co mponents [2-4]. PA NI is one of the conducting polymers that has potential in the near term, due to its good p ro cessab ility , en v iron ment al stab ilit y and reversible control of conductivity both by charge-t ransfer doping and protonation[5-6]. Inorganic semiconductors CdS, ZnS and PbS nanopart icles are the most pro mising II-VI compound materia ls used in various applications like sensors, optoelectron ic d ev ices and in solar cells [7]. Stud ies on PANI-Cd S, PA NI-ZnS and PANI-PbS nanocomposite have been reported by many researchers [8-11] and focused on electrical conductivity, but little is known about the thermal thermal stab ility o f such n ano co mpos ites . A long with elect rical conduct ivity , thermal stability o f the poly mers plays important role to modify the polymer properties to be used for advanced applications. Hence thermal stability of conducting PANI and its co mposites has great importance. * Corresponding author: jitendrabbhaiswar@yahoo.co.in (J. B. Bhaiswar) Published online at https://www.eduzhai.net Copyright © 2013 Scientific & Academic Publishing. All Rights Reserved This paper present d.c electrical conductivity and thermal stability of PA NI/PbS nanocomposite using fore probe technique and TGA (thermogram) with d ifferent wt % of PbS and also study thermal parameter using DTA analysis. 2. Experimental Part PbS (A ldrich) and aniline (A ldrich) were used after purification. Oxidant Ammon iu m per sulphate (Aldrich) was used without further purification. 2.1. Synthesis of Pol yaniline vi a Chemical Oxi dati ve Polymerization Poly merization was carried out by the chemical o xidation of aniline in the presence of H2SO4 and APS (A mmoniu m per-sulphate) in 100ml distilled water both played the role as dopant and oxidant respectively. (0.4mol) APS was dissolved in 100ml distilled water in a four-neck round bottom reaction flask and 0.4mo l H2SO4 is also added under mechanica l stirring for 2 hours. Aniline (0.4 mol) was stirred with 0.4mo l of H2SO4 in 100ml distilled water. The solution of APS in H2SO4 was then added drop-wise in the solution of aniline with vigorous stirring on a magnetic stirrer for 3 hours to initiate the aniline poly merization. The reaction was later carried out at roo m temperature fo r 6-7 hours with stirring. A dark green colored PAni suspension was obtained with p recipitation. The synthesized PAni was obtained as finely dispersed particles, wh ich were recovered fro m the polymerization mixture by centrifugation and washed with deionized water repeatedly until the washing liquid was 116 J. B. Bhaiswar et al.: Synthesis, Characterization, Thermal Stability and D.C. Electrical Conductivity of Pani/Pbs Nanocomposite completely colourless. Finally, the mixture was filtered using filtered assembly. After keeping overnight, the dark gray colour precipitate was obtained. A precipitate of Polyaniline was dried under at 60 − 80℃ for more than 8 h o u rs . 2.2. Synthesis of PAni-PbS Nanocomposites The synthesis steps of PAni/PbS nanocomposite are similar to the synthesis method of PAni. Different amount of PbS was dispersed into the APS solution and stirred for 1 hour prior to the addition of aniline. Aniline (0.4 mo l) stirred with 0.4mo l H2SO4 in 100 ml of distilled water were added drop-wised using burette into the APS-PbS solution and stirred vigorously to form ho mogeneous dispersion. For convenience, PAni Co mposites were prepared with different weight percentages of PbS i.e. 5%, 10%, 15%, 20% & 25%%. Same synthesis conditions were maintained for all composites as that of pure PAni to compare the result. Characterizati ons X-RD spectra of all samples were taken on Philips PW 3071, Automatic X-ray diffracto meter Using Cu-Kα radiation of wavelength 1.544 Å, continuous scan of 2 o / min., with an accuracy of 0.01 at 45 KV and 40 mA. Fourier Transform Infra Red (FTIR) spectroscopy (Model: Perkin Elmer 100) of PAni: PbS nanocomposite was studied in the frequency range of 400–4000 cm−1. UV-spectra were recorded in the region 200 – 800 n m at a scanning rate of 100 nm min-1 and a chart speed of 5 cm min-1. TGA thermograms of all samples were recorded on Perkin-Elmer Diamond TGA/DTA in argon atmosphere at a heating rate of 10℃/ min. TGA profile were taken over the temperature range of 30-800℃. The electrical conductivity measurement were made using four probe techniques. TEM micrographs of synthesized PAni/ PbS were taken on Transmission Electron Microscope PHILIPS model- CM200 with resolution 2.4Å. 3. Result and Discussion 3.1. XRD Analysis Fig. 1. Shows the XRD spectra of pure PAni, Pure PbS and PAni/PbS nanocomposite. The XRD pattern of pure PAni matchable with the JCPDS file no-53-1891 with 2θ=25.12 and d-spacing 3.54Å.A nanocomposite of Pani shows the greater crystallin ity due to the addition of PbS in PANI matrix as compared to pure PANI and pure PbS. The crystalline size of the crystalline particle can be determined using Debye Scherer formu la 0.9×???? and it is found that the ???????????????????? grain size of PAni/PbS nanocomposite is (82.10n m). Figure 1. XRD Pattern of pure Pani, pure Pbs and Pani/Pbs nanocomposite International Journal of Composite M aterials 2013, 3(5): 115-121 117 3.2. FT-IR S pectra Figure 2. FT-IR spectra of Pure Pani, Pani/PbS and Pure PbS Fig.2. shows the FT-IR spectrum of pure polyaniline, pure PbS and PAni/Pb S nanocomposite, where the % of transmittance is plotted as a function of wave number (cm-1). The characteristic FT-IR pea k at 1566 and 1485 c m-1 are due to the presence of quinoid and benzenoid rings, respectively and are clear indication of these two states in the polymer chain. Also, The peaks at 1302 cm-1 are due to the C-N bond stretching vibration. The absorption band near 2900 cm-1 is assigned to aliphatic C– H stretching of the Poly mer. The peak at 819cm-1 attributes due to the para coupled ring while peak at 880 cm-1 represents the deformed vibrational mode of benzene ring, which is caused due to attachment of specific group present on the ring. The FTIR spectra of composite materia ls are shown in figure. The C=C vibrations of quinoid and benzenoid ring is observed at 1566-1482 cm-1 in composites. The peak due to methyl group attached to the phenyl ring is observed at 820-881cm-1. The characteristic peaks observed at 1146 cm-1 are due to symmetric stretching vibrations of -SO3 (polystyrene sulphonic acid). The weak vibration bond at 415 shows that concentration of PbS in the polymer is low. 3.3. TEM Micrograph Figure 3. TEM of Pani/PbS nanocomposite 118 J. B. Bhaiswar et al.: Synthesis, Characterization, Thermal Stability and D.C. Electrical Conductivity of Pani/Pbs Nanocomposite may be due n→π* transition[12]. The UV-visible spectra of PANi/ PbS nanocomposite shows the bathochromic shift i.e. the shift towards the longer wavelength in which the value of λmax increases. The absorption peak at 285n m and 768n m in PAni/PbS nanocomposite matches with pure PAni and Pu re PbS confirm the fo rmation of nanocomposite. Figure 4. TEM of Pure PbS Fro m the fig 3&4 clear that Pani/PbS nanocomposite and Pure PbS synthesized by chemical o xidation technique are in nanorange with the nanoscale of 60n m and 100n m range respectively with average diameter of 21n m. 3.4. UV-Visible Anal ysis Fig.5. Shows the UV-spectra of pure PAni, PAni/PbS nanocomposite and Pure PbS were recorded in the region 200 – 800 n m at a scanning rate of 100 n m min-1 and a chart speed of 5 cm min-1. The Pure PAni d isplayed two characteristics broad band’s at 285 and 375n m. The band at 375 cm-1 is the less intense band which may be accounted for a π→π* transition while the more intense band at 285 nm 3.5. TGA Thermogram Fig 6. shows TG thermogram of pure Pan i and Pani/PbS nanocomposite. The TG thermogram of pure Pani shows three major stages for the weight loss up to 800℃. The first weight loss of 23% at around 120℃ is due to evaporation of mo isture. The second stage of weight loss starting at 150℃ up to 350℃ almost 50% substance wt loss which represents the evaporation and degradation of sulphuric acid group and low mo lecular weight poly mers [13]. Fro m 350℃ onwards, degradation of skeletal PANI Chain structure takes place[14] up to 800℃ in which almost 93% mass loss is observed. The TGA thermograms of PA NI-Pbs nanocomposite containing different weight percentage of PbS are shown in fig.3) respectively. It was observed that PANI-PbS nanocomposite containing 5%, 10%, 15% and 20% and 25% weight of Pbs shows weight loss of 15to 8% at 120℃ which is less than PANI. Similarly it shows second stage of degradation between 150-300 ℃ . Above 300oC, poly mer degradation takes place slowly up to 800℃ unlike pure PANI which almost degrades at 800℃. Conclusively, the TGA studies point out the inference that, PANI-Pb S nanocomposite are thermally mo re stable than pure PANI salt. Absorption pure PbS 3.5 PANI/PbS nanocomposite pure PANI 3.0 2.5 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 200 300 400 500 600 700 800 Wavelength(nm) Figure 5. UV-Spectra of Pure Pani, Pani/PbS and Pure PbS International Journal of Composite M aterials 2013, 3(5): 115-121 119 110 100 90 80 70 60 50 40 30 20 10 0 3.6. DTA Analysis % Weight(%) 5% PAni/PbS 10% PAni/PbS 15% PAni/PbS 20% PAni/PbS 25% PAni/PbS Pure PAni 0 100 200 300 400 500 600 700 800 900 Tempreture(0C) Figure 6. T GA thermogram of Pani/PbS nanocomposite at different wt(5-25%) 5% PAni/PbS 10 10% PAni/PbS 15% PAni/PbS 20% PAni/PbS 5 25% PAni/PbS 0 Heat flow -5 -10 -15 -20 0 % nanocomposite 5% 10% 15% 20% 25% 100 200 300 400 500 600 700 800 900 Tempreture(0C) Figure 7. DT A of PAni/PbS nanocomposite at different wt ratio (5-25%) Table 1. DTAresult of PAni/PbS nanocomposite at different wt ratio Onset temp 242.59℃ 244.15℃ 233.06℃ 227.55℃ 237.25℃ Peak temp 268.38℃ 267.88℃ 256.81℃ 267.13℃ 266.42℃ Enthalpy change(∆H) 47.3679J/g 34.4645 J/g 30.4788 J/g 60.6998 J/g 36.8611 J/g Area 264.377mJ 167.613 mJ 123.622 mJ 308.707 mJ 152.234 mJ End temp 283.71℃ 279.39℃ 274.50℃ 291.36℃ 289.35℃ 120 J. B. Bhaiswar et al.: Synthesis, Characterization, Thermal Stability and D.C. Electrical Conductivity of Pani/Pbs Nanocomposite Fig. 7. The DSC curve peaks indicates the endothermic process where energy is required to break the bonds in the successive elimination of H2O, CO and CO2. Table.1. shows DTA result of PAni/PbS nanocomposite with different wt % of PbS (5-25%). All nanocomposite has higher peak temperature than 15% nanocomposite. The increased in wt % of PbS in the PAni matrix, no significant effect on peak temperature and enthalpy change. However the onset temperature of PAni/PbS (5-25%) nanocomposite are less than pure PAni(2980) that clearly indicated the therma l stability of PAni/PbS nanocomposite are greater than pure PAni. 3.7. D.C. Electrical Conducti vity Log(6)(S/cm)x10-3 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -0.8 -0.9 -1.0 -1.1 -1.2 -1.3 -1.4 -1.5 -1.6 2.4 2.6 2.8 3.0 1000/T(K-1) 5% Pani/PbS 10% Pani/PbS 15% Pani/PbS 20% Pani/PbS 25% Pani/PbS 3.2 3.4 Figure 8. D.C.electrical conductivity of Pani/PbS nanocomposite (5-25%) Fig.8. Shows the variation of electrical conductivity (σ) with increasing doping concentration of PbS into PANi measured according to the standard four point probe method at room temperature. It is observed that the room temperature conductivity of PANi/PbS nanocomposite increases remarkably fro m 4.10 x 10−5 S/cm (5%) to 1.68 ×10−3 S/cm (25%) as doping concentration of PbS increased fro m 5 - 25 wt%. The conductivity continues to increase with increasing PbS content into PANi/PbS nanocomposite. This may be attributed to the doping effect of PbS which maximizes the number of ca rriers. FT IR and XRD pattern are de monstrated that PbS nanoparticles had been successfully incorporated into polymer chain. Fro m this result it is believed that intercalation of PbS nanoparticles in polyaniline were helped to increase the conductivity due to enhancement of crystalline o f PbS nanoparticles. The conductiv ity o f PbSpolyaniline (1.68x10-3 S/cm) nano-co mposite was greater than pure polyaniline (10-10 S/cm)[15] and Silicon (10-4S/cm) s emico n d u cto rs . synthesized via in situ by oxidation poly merization. FT -IR, XRD and UV-Visib le spectra demonstrated that the PbS nanoparticles disperse in polymer matrix.TEM is clearly indicated that the nanocomposite are in nanorange. Electrical conductivity of Po lyaniline–PbS nanocomposites was found to be increased when compared to pure Polyaniline due to its increase in crystallinity. TGA/ DTA thermogram clearly indicated increased in thermal stability of PAni/PbS nanocomposite at different % of PbS as compared to Pure PAni. REFERENCES [1] Y Wang, H erron N,”Photoconductivity of Cd S nanoclusterdoped polymers “Chemistry and Physics letters, volumn 200, no.1-2, pp.71-75,1992. [2] A.Lagashetty and A. Venkataraman, Resonance, (2005) 49-60. 4. Conclusions [3] M . D. Ventra, S. Evoy, J. R. Heflin‚ "Introduction to Nanoscale Science and Technology", Kluwer Academic Polyaniline-CdS nanocomposites have been successfully Publishers, (2004). International Journal of Composite M aterials 2013, 3(5): 115-121 121 [4] S. Aoshima , F. R. Costa , L. J. Fetters , G. Heinrich , S. Kanaoka, A. Radulescu , D. Richter , M . Saphiannikova , U. Wagenknec Int. J. Electrochem. Sci., Vol. 6, 2011, 220 [5] J. Jiang, L. Li, M . Zhu, Reactive & Functional Polymers 68 (2008) 57–62. [6] Heeger, A.J. (2001). Semiconducting and metallic polymers: The fourth generation of polymeric materials. J. Phys. Chem. B, 105(36), 8475. [7] Shubhangi D. Bompilwara, Subhash B. Kondawarb, Vilas A. Tabhane, Snehal R. Kargirward, Pelagia Research Library, Advances in Applied Science Research, 2010, 1 (1): 166-173 [8] Xiaofeng Lu, Youhai Yu, Liang Chen, Huaping M ao, Wanjin Zhang & Yen Wei, Chem. Commune. 2004, 1522-1523[DOI: 10.1039/b403105a] [9] X. Y. M a, G. X. Lu, B. J. Yang, Applied Surface Science, 187, 2002, 235-238 [10] Fan Jun, Ji Xin, Zhang Weiguang, Yan Yunhui, CJI, 6, 7, 2004, 45-49 [11] D. Y. Godowsky, A. E. Varfolomeev, D. F. Zaretsky, J. M ater. Chem, 11, 2001, 2465-24. [12] Silverstein R M , Bassler G C, M orrill T C, (1991) Spectrometric Identification of organic Compounds, 5th Edi, John Wiley and Sons. Inc. Printed in Singapore. [13] A. L. Sharma, V. Saxena, S. Annopoorni, B. D. M alhotra, J. Appl. Polym. Sci. 81, 2001, 1460-1466 [14] R. K. Paul, C. K. S. Pillai, Polym. Int. 50, 2001, 381–386 [15] Kose T.D, Ramteke S.P.international journal of composite materials: 2012, 2(4); 44-47.

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