Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 2(12), 11-16, December (2012) Res.J.Chem. Sci. International Science Congress Association 11 Thermal Degradation Analysis of Melamine-Aniline-Formaldehyde Terpolymeric Ligand Dharkar K.P., Khamborkar A.K. and Kalambe A.B. Department of Chemistry, Institute of Science, Nagpur– 01, MS, INDIA Department of Statistics, Sydenham College, Mumbai –20, MS, INDIAAvailable online at: www.isca.in Received 31st May 2012, revised 11th June 2012, accepted 25th June 2012Abstract Terpolymeric ligand MAF has been synthesized by the condensation of melamine (M) and aniline (A) with formaldehyde (F) in the presence of an acid catalyst in 1:2:4 molar proportions of the reacting monomers. The characterization of terpolymeric ligand has been done on basis of elemental analysis, IR and HNMR. Thermal decomposition curve shows single decomposition step (305-530 C). Thermal activation energy (E) calculated by Sharp-Wentworth (21.10 KJ/mole) method and Freeman-Carroll (21.46 KJ/mole) method are in good agreement. Freeman - Carroll and Sharp -Wentworth methods have been applied for the calculation of kinetic parameters while the data from the Freeman - Carroll methods have been used to determine various thermodynamic parameters. Keywords: Terpolymeric ligand, Decomposition, Sharp-Wentworth method, Freeman-Carroll method, Thermodynamic parameters. Introduction Considerable amount of work has been reported on various copolymers, synthesized by the condensation of a mixture of phenol or various amines, and formaldehyde. These resins have a large number of practical applications in electronic controls, insulating materials, protective adhesives, aerospace industries etc. because of their high thermal stability, heat and chemical resistance and electrical insulation properties2,3. Various researchers have studied the applications of terpolymeric ligand of substituted phenols and formaldehyde. By and large the studies of the thermal degradation of copolymer resins have become a subject of interest. Thermo- gravimetric study of 8-hydroxyquinoline-melamine- formaldehyde resin has also been carried out. Terpolymer resins based on substituted -cresol and melamine with formaldehyde have been synthesized and studied for its thermal properties. The present communication deals with synthetic and thermal degradation properties of a newly synthesized terpolymeric ligand derived from melamine (M) and aniline (A) with formaldehyde (F). The elemental analysis has been carried out to ascertain the molecular formula and spectral analysis has been used to characterize the MAF terpolymeric ligand. The Freeman – Carroll and Sharp- Wentworth methods have been applied for the calculation of kinetic parameters7,8. Methods for the estimation of kinetic parameters from thermo-gravimetric studies are generally based on the assumption that the Arrhenius equation is valid with thermal and diffusion barriers are negligible. Material and MethodsAll the chemicals used were of analytical reagent grade. DMF was used after distillation. Synthesis of Polymeric ligand: For synthesis of terpolymeric ligand9,10 a mixture of melamine (0.05 mole), aniline (0.1 mole), formaldehyde (0.2 mole) in 200 ml HCl (2M) was refluxed on oil bath for 6 hours with occasional shaking. The temperature of electrically heated oil bath was controlled with the help of dimmerstat. The resinous solid product obtained was immediately removed from the flask as soon as the reaction period was over. It was then purified by dissolving in (1M) sodium hydroxide solution, filtered and re-precipitated by gradual drop wise addition of ice cold (2M) HCl with constant and rapid stirring to avoid lump formation. The MAF terpolymeric ligand so obtained was filtered, washed several times with hot water, dried in air, powdered and kept in vacuum desiccators over silica gel. The sample and amount of reactant of MAF terpolymeric ligand is given in table-1. The estimation of carbon, hydrogen and nitrogen was done by the elemental analyzersElementar Vario EL III Carlo Erba 1108 from C.D.R.I., Lucknow (India). Infrared spectra of the ligand was scanned at SAIF Chandigarh (India), in KBr pellet on Perkin Elmer, RX I in range 4000-500 cm-1. NMR spectra were recorded on 60 MHz for one hour using BRUKER AVANCE II 400 NMR spectrometer at SAIF, Chandigarh (India). The spectra were recorded in (DMSO) d6 solvent. Thermal analysis: Thermal analysis method is associated with a change in weight with respect to temperature. Heating is Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 2(12), 11-16, December (2012) Res. J. Chem. Sci. International Science Congress Association 12 performed under strictly controlled conditions and can reveal changes in structure and other important properties of the material being studied. In non-isothermal or dynamic TGA, the sample is subjected to condition where temperature is increased at linear rate. Thermo-gravimetric analysis (TGA) of polymer sample was carried out by using Perkins Elmer Diamond thermal analyzer at heating rate of 10 C per minute and in air atmosphere up to 1000C. The thermograms were recorded at Visvesvaraya National Institute of Technology, (VNIT) Nagpur (India). The Freeman - Carroll and Sharp - Wentworth methods have been employed for the calculation of kinetic parameters of the newly synthesized terpolymeric ligand with help of dynamic TG curve11,12 The advantage of Freeman - Carroll method is that by keeping heating rate constant, both the order of reaction and energy of activation can be calculated in a single experiment. The following expression is used to evaluate various kinetic parameters13,14 like activation energy (Ea), entropy change (S), free energy change (F), frequency factor (Z), apparent entropy change (S*) and the order of reaction (n) of the terpolymeric ligands and polychelates Hence, a plot of log[dC / dt] / log W Vs [1/T] / log W should give a straight line with an intercept on -axis equal to the value of n (order of reaction) and the slope m = Ea / 2.303R. Where, dCw/dt is the rate of change of weight with time and in expression Wr = Wc –W, Wc is the weight loss at the completion of the reaction, w is the total weight loss up to the time t and T is the temperature. The following expression is used to evaluate Ea with Sharp- Wentworth method Where, dCw / dt is the rate of change of mass with time t, T is the temperature and = dT/dt Results and DiscussionThe newly prepared terpolymeric ligand was found to be yellow coloured solid soluble in dimethylformamide and dimethylsulphonoxide. Characterization of terpolymeric ligand: The composition of terpolymeric ligand obtained on basis of elemental analysis data as shown in table-2 was found to be in good correlation to that of calculated values. A sharp band appearing in the region 3350 cm-1 may be due to the stretching vibration of -NH- group15,16. The inflections around 1440.5cm-1, 1265.0 cm-1 and 750.7 cm-1 suggest the presence of bending, wagging, rocking vibrations of methylene (-CH-) bridges in polymeric chains17,18. The sharp peak at 1610 cm-1 may be due to aromatic skeletal ring. The band presence at 1460 cm-1 may be due to symmetric tri-substituted melamine ring16,17,19. The broad bands at 1485.0 cm-1, 770.4 cm-1 suggest the presence of -NH-bending, wagging in terpolymeric ligand respectively17,20. The IR spectral data of MAF terpolymeric ligand is summarized in table-3. The NMR spectrum of the MAF terpolymer exhibit signal in the region of 6.34-7.36 (ppm), which may be due to the protons of the aromatic rings (Ar-H)21,22. The presence of a broad signal around 6.32 (ppm) is due to -NH- attached to melamine ring which is mixed with NH- of aromatic ring19 . The presence of a broad signal around 6.89 (ppm) is attributed to the presence of –NH bridges20,22A methylene protons Ar-CH- Ar appear as a singlet at 3.55 (ppm)23The spectral data is tabulated in table-4.Table-1 Sample and amount of reactants of [MAF] terpolymeric ligand Reactants (in moles) Catalyst 2M HCl (aq.) (ml) Reflux temp. ± 20 C Terpolymeric ligand Abbreviation Molar ratio of reactant Yield (%) M.P. (K) A F 0.05 0.1 0.2 200 102 [MAF] 1:2:4 75 578 * M = Melamine A = Aniline F = Formaldehyde Table-2 Analytical Data of [MAF] terpolymeric ligand Terpolymer Empirical Formula %C %H %N Found Cal. Found Cal. Found Cal. [MAF] C19 H22 N 62.81 62.98 6.06 6.08 30.85 30.94 EadtdC303.2loglog log303.2EalogdtdClog Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 2(12), 11-16, December (2012) Res. J. Chem. Sci. International Science Congress Association 13 Table-3 IR Spectral data of [MAF] terpolymeric ligand Assignments Observed band Frequency (cm-1) Expected band Frequency (cm-1) �NH stretch 3350 3500-3200 Methylene bridge (-CH) mode 1265 (w) 1440.5 (b) 750.7 (r) 1300-1200 1460 775 Tri -substituted melamine ring 1460 ~1470 N-H wagging 770.4 650-800 N-H bending 1485 1400-1500 Table-4 H-NMR spectral data of [MAF] terpolymeric ligandNature of proton Chemical Shift (ppm) Expected Chemical Shift (ppm) Aromatic (Ar-) 6.34-7.36 6.2-8.5 -NH- melamine 6.32 6.2-6.8 Ar – C 2 -N 2.7 2.5-3 -N bridging 6.89 5.4-8.5 Ar-C 2 - Ar 3.55 2.7-4.3 Table-5 Activation energy and decomposition temperature of [MAF] terpolymeric ligand Terpolymeric Ligand Decomposition temperature (C) Activation Energy (kJ/mol) FC SW [MAF] n 390 21.46 21.10 FC – Freeman-Carroll, SW – Sharp –Wentworth Thermo-gravimetric studies of MAF ligand: Thermo-gravimetric analysis24 of MAF ligand has been carried out and thermogram and kinetic plots for MAF terpolymeric ligand are given in figure-1, figure-2 and figure-3. The thermogram exhibits single decomposition step (305-530 °C). MAF terpolymeric ligand is stable up to 305°C. Up to 530°C gradual mass loss is observed because of the decomposition of polymer and beyond 530°C no mass loss takes place. This shows the formation of a stable species. The decomposition temperature for MAF terpolymeric ligand is 390°C. (Total mass loss: Calc. 79.34%, Obs. 78.00%). Thermogram of MAF Terpolymeric ligand shows activation energy calculated by the Freeman - Carroll and Sharp - Wentworth methods are in good agreement with each other as given in table-5. Thermodynamic parameters have been calculated on the basis of thermal activation energy and values are given in table-6. Due low value of frequency factor [Z] it may be classified as a slow reaction. The negative value of entropy [S] indicates that the activated polymer has more ordered structure than the reactants and the reactions are slower than normal. This is further supported by low Z value25,26. It is very difficult to draw any unique conclusion from the magnitude of thermal activation energy [Ea] as decomposition mechanism is expected to be complicated. Positive values of activation energy under present investigation correspond to the energy of activation due oxidation – reduction process of terpolymer in the higher temperature range27. Fairly straight-line plots are obtained using the two methods. However, while using the Freeman- Carroll method some abnormal points were ignored to get a clear picture about most of the points. Similarly, in the Sharp- Wentworth method, some points at the beginning or at the end did not fall on straight line. This is expected, since, the decomposition of terpolymer is not obeying first order kinetics perfectly. These observations are in harmony with the findings of other earlier work28. ConclusionThe newly prepared terpolymeric ligand was found to be yellow coloured solid soluble in dimethylformamide and dimethylsulphonoxide having a melting point 578K. The thermogram exhibits single decomposition step (305-530°C). The decomposition temperature of MAF terpolymeric ligand is 390°C.Thermal activation energy () calculated by Sharp-Wentworth (21.10 KJ/mole) has been found to be in agreement with that calculated by Freeman-Carroll (21.46 KJ/mole) method. AcknowledgementThe authors are thankful to Director, Institute of Science, Nagpur for providing the laboratory facilities to carry out this work. Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 2(12), 11-16, December (2012) Res. J. Chem. Sci. International Science Congress Association 14 Table-6 Kinetic parameter of [MAF] terpolymeric ligand Terpolymeric Ligand Entropy Change S (J) Free energy change F (kJ) Frequency factor Z (s-1) Apparent entropy change S* (J) Order of reaction (n) [MAF] n -154.54 110.79 334.78 -203.26 0.83  Figure-1 Thermogram of [MAF] 0.51.52.5-0.0009-0.0008-0.0007-0.0006-0.0005-0.0004-0.0003-0.0002 Figure-2 Freeman - Carroll plot for [MAF] terpolymeric ligand 1/T/ Log Wr Log dCw/dt/Log Wr Temperature ( O C) % Mass Loss Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 2(12), 11-16, December (2012) Res. J. Chem. Sci. International Science Congress Association 15 -1.8-1.5-1.2-0.9-0.6-0.30.0010.00110.00120.00130.00140.00150.00160.00170.0018 Figure-3 Sharp - Wentworth plot for [MAF] terpolymeric ligand References1.Singru R.N., Zade A.B. and Gurnule W.B., Synthesis, characterization, and thermal degradation studies of copolymer resin derived from -cresol, melamine, and formaldehyde, J. Appl. Poly. Sci.,9(2) 859–868 (2008)2.Ghosh Pranab, Das Tapan and Das Moumita, Evaluation of poly (acrylates) and their copolymer as viscosity modifiers, Res.J.Chem.Sci., 1(3), 18-25 (2011)3.Masram D.T., Thermal degradation study of salicylic acid, diaminonaphthalene and formaldehyde terpolymer, E-J Chem., 6(3), 830-834 (2009) 4.Das A.P., Lenka S. and Nayak P.L., Synthetic resins: I. Preparation and characterization of resins from substituted benzoic acid–formaldehyde, J Appl. Polym. Sci., 30, 4619 (1985)5.Singru R.N. and Gurnule W.B., Thermogravimetric study of 8-hydroxyquinoline 5-sulfonic acid-melamine-formaldehyde terpolymer resins, J. Thermal Analysis & Calorimetry,100(3), 127 (2010)6.Singru R.N., Zade A.B. andGurnule W.B., Synthesis, characterization, and thermal degradation studies of copolymer resin derived from p-cresol, melamine, and formaldehyde, J App.l Polym. Sci.,109(2), 859-868 (2008)7.Freeman E.S. and Carroll B., The application of thermoanalytical techniques to reaction kinetics: the thermogravimetric evaluation of the kinetics of the decomposition of calcium oxalate monohydrate, J Phys. Chem. 62(4), 394-397 (1958)8.Sharp J.H. and Wentworth S.A., Kinetic analysis of thermogravimetric data, Anal. Chem., 41, 2060-2062 (1969)9.Hiwase V.V., Kalambe A.B., Khedkar K.M. and Deosarkar S.D., Ion exchange properties of resins derived from p-hydroxybenzaldehyde, resorcinol and formaldehyde, E-J Chem.,7(1), 287-294 (2010)10.Gurnule W.B., Juneja H.D., Paliwal L.J. and Kharat R.B.,Synthesis and characterization of copolymer derived from 2-hydroxy acetophenone, oxamide and formaldehyde, Prog.Crystal Growth Charct. Mater., 45, 155-160 (2002)11.Masram D.T., Kariya K.P. and Bhave N.S., Synthesis of resin I: salicylic acid, hexamethylenediamine and formaldehyde and its ion-exchange properties E-Polymer, 75(2007)12.Jadhao M.M., Paliwal L.J. and Bhave N.S. and Resin I., Synthesis and characterization of 2,2dihydroxybiphenyl–urea–formaldehyde terpolymers, J Appl. Polym. Sci.,96(5), 1605-1610 (2005)13.Ukey V.V., Juneja H.D., Borkar S. D., Gubde R. S. and Naz S., Preparation, characterization, magnetic and 1/T (Thousandth) Log[(dCw/dt)1-Cw] Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 2(12), 11-16, December (2012) Res. J. Chem. Sci. International Science Congress Association 16 thermal studies of some chelate polymers of first series transition metal ions J Mat. Sci. & Eng., B132, 34-38 (2006)14.Michael P. E. P., Barbe J. M., Juneja H. D., Paliwal L., Synthesis, characterisation and thermal degradation of 8 – hydroxyquinoline – guanindine - formaldehyde terpolymer, J., European Poly. Journal, 43, 4995-5000 (2007)15.Willard H. H., Merritt L. I., Dean J. A. and Seattle F.A., Instrumental methods of analysis, CBS: New Delhi (1986)16.Kalsi P. S., Spectroscopy of organic compounds, IIndEd., New Age International: New Delhi (1995)17.Kemp W., Organic spectroscopy, The Macmillan Press, Hong Kong Press (1975)18.Dunn G. E. and McDonald R. S., Infrared spectra of aqueous sodium benzoates and salicylates in the carboxyl-stretching region: chelation in aqueous sodium salicylates, Can. J Chem., 47(24), 4577-4588 (1969)19.Bajia S., Sharma R. and Bajia B., Solid-state microwave synthesis of melamine-formaldehyde resin,E J-Chem. 6(1), 120-124 (2009)20.Nakanishi K., Infrared absorption Spectroscopy practical, Nolden Day and Nankod, Tokyo (1967)21.Dyer J. R., Application of absorption spectroscopy of organic and biological chemistry, MIR: Moscow (1975)22.Vogel A. I., Textbook of practical organic chem.Longman Scientific and Technical, UK (1989)23.Silverstein R. M. and Bassler G. C., Spectrometric identification of organic compounds, IInd Ed., John Wiley: New York (1967)24.Chaudhary Rakhi and Shelly, Synthesis, spectral and pharmacological study of Cu(II), Ni(II) and Co(II) coordination complexes, Res.J.Chem.Sc., 1(5), 1-5(2011) 25.Coats A.W. and Redfen J.P., Kinetic parameters from thermogravimetric data, Nature 201, 68-69 (1964) 26.Ozawa T.J., Critical investigation of methods for kinetics analysis of thermoanalytical data, J. Thermal Anal., 7, 601-617 (1975) 27.Gupta R.H., Zade A.B. and Gurnule W.B., Synthesis and characterization of terpolymers derived from 2-hydroxyacetophenone, melamine, and formaldehyde, J. Appl Poly. Sci.,109(5), 3315–3320 (2008)28.Jacobs P. W. M., Tompkin F. C., Chemistry of solids state, E.G Garner Publication, London (1955)