The objective of our work consists in synthesizing a new bifunctional epoxy resin in which the aromatic radical matrix contains connections (C = C, C = N, CC and CS) by two stages. In the first course, we obtained the precursor molecule of the epoxy matrix (6- (4-chlorophenyl) -5-ethoxy-4-methyl-1, 6-dihydropyrimine-2-thiol) .The second stage tended to functionalize the latter by the epichlorohydrin. The microscopic characterization of the synthesized resin was: confirmed by the Infra-red Fourier transform (FTIR) and the nuclear magnetic Resonance (NMR), on the one hand, while the parameter of viscosity was evaluated on the other hand

atiqa, bekhta

El Aouni, N.

El Azzaoui, J.

El Elhilal, B.

Elharfi, A.

English

Revues Scientifiques Marocaines

Bekhta & al. / Mor. J. Chem. 3 N°3 (2015) 458-464  458     Synthesis, viscometric and microscopic characterization of a new bifunctional sulfur epoxy resin.  A. Bekhta (a)*, J. El Azzaoui(a), N. El-Aouni(a), B. El Elhilal(a) and A. Elharfi(a)  (a)Laboratory of Polymers, Radiation and Environment (LPRE), Team of Organic and Macromolecular Chemistry (ECOM), Department of Chemistry, Faculty of Science, University Ibn Tofail, BP133, 14000, Kenitra, Morocco  *Corresponding author. E-mail : abekhta@gmail.com Received 08 March 2015, Revised 20 May 2015, Accepted 26 May 2015.   Abstract The objective of our work consists in synthesizing a new bifunctional epoxy resin in which the aromatic radical matrix contains connections (C = C, C = N, CC and CS) by two stages. In the first course, we obtained the precursor molecule of the epoxy matrix (6- (4-chlorophenyl) -5-ethoxy-4-methyl-1, 6-dihydropyrimine-2-thiol) .The second stage tended to functionalize the latter by the epichlorohydrin. The microscopic characterization of the synthesized resin was: confirmed by the Infra-red Fourier transform (FTIR) and the nuclear magnetic Resonance (NMR), on the one hand, while the parameter of viscosity was evaluated on the other hand.  Keywords: viscometric ; bifunctional ; polyepoxides.  1. Introduction Thermosetting resins including polyepoxides are matrices of high performance polymers by excellence. [1] These are synthesized by polycondensation [2,3]. Epoxy resins contain at least two epoxy groups (oxirane) which are highly reactive and generally obtained by making the epichlorohydrin react with an active center such as the diol. Polyepoxides are commonly used as adhesives or paints. Their chemical properties make them useful in food and construction industry [5]. They are also polymers, which are used in various application areas [4] (coatings, reinforced concrete, burial of radioactive waste and etc ...). The knowledge of the rheological properties of these thermosetting materials on a wide range of temperature is necessary for both the understanding and the mastery of the storage conditions. [9] The performance and quality of implementation of their materials is instinctively dependent on their storage conditions. These rheological properties can also be related to the chemical structure or the degree of conversion of the prepolymer polyepoxide [10].The microscopic structural characterization was obtained by using the Fourier Transform Infrared (FTIR), and the nuclear magnetic resonance (NMR)). The characterization of our macroscopic bifunctional resin was performed by viscometry using the Ubbelohd viscometer. Bekhta & al. / Mor. J. Chem. 3 N°3 (2015) 458-464  459  2. Materials and methods 2.1. Equipments used The basic chemicals are: chlorobenzaldehyde, thiourea, ethyl acetoacetate epichlorohydrin with a purity of 99% methanol and triethyl amine. These commodities have been provided by the companies Acros Chemical Co and Aldrich Chemical Co without any further purification.  2.2. Methods of analysis 2.2.1. Nuclear magnetic resonance (NMR) The 1 H NMR analysis, 13 C NMR were obtained using the “Bruker AVANCE 300MHz" device  by dissolving the product in DMSO at 60 °C. The chemical shifts were expressed in ppm; the coupling constants by Hz and the following abbreviations have been used: s, d, dd, t, q and m. They respectively stand for singlet, doublet, doubled doublet, triplet, quadruplet and multiplet.  2.2.2. Infrared analysis Fourier transform (FT-IR) The IR spectrometer used is BRUKER FTIR. The spectra were carried out in transmission on KBr pellets. The light beam passes through the sample to a thickness of about 2 * m and the analysis is performed between 600cm-1 and 4000cm-1.  2.2.3. the viscometric analysis The viscometric analysis of the standard matrix is followed by a capillary viscometer Ubbelohd VB-1423 tube.The selected measuring conditions are as follows:  Viscometer 1B size for a series of dilution; capillary tube diameter of 0.46 mm  Constant k = 0.051493.  Measuring temperature in ° C:  30 up to 45  Number of measurements: 4 in each time  Solvent: Methanol  Hagenbach correction was calculated using the formula which is given in the DIN 1999 standard 51562-1 “Janvier” (Measurement of kinematic viscosity by means of the Ubbelohd of viscometer).  The solubilization of epoxy resin pre-polymers in methanol was carried out under magnetic stirring at 20 ° C.  2.3. Experimental Protocol 2.3.1. Synthesis of DGECEPMMC resin Mono- or multi-functional epoxy resins are generally synthesized according to two routes the first of which is based on two stages and the second on only one. The Resin of DGECEPMMC Diglycidyl Ether (6- (4-chlorophenyl)-5-ethoxy-4-methyl-1,6-dihydropyrimine-2-thiol) was synthesized according to the literature procedures [6, 7,8]. In this case, they are obtained by two steps: The first step: the product synthesis CEPMMC (6- (4-chlorophenyl) -5-ethoxy-4-methyl-1,6-dihydropyrimine-2-thiol) from ethyl acetoacetate, 4-chlorobenzaldehyde and thiourea, using a protocol adapted by the Italian chemist "Pietro Biginelli" in 1893 [17, 18]. Bekhta & al. / Mor. J. Chem. 3 N°3 (2015) 458-464  460   Figure 1: Synthesis of CEPMMC resin. 2nd step: Poly-condensation of epichlorohydrin CEPMMC.  Figure 2: Synthesis of the new DGECEPMMC resin.  2.3.2. Procedure: In a round bottom flask, we mixed 3g of CEPMMC dilute solution in 20 ml of methanol and a stoichiometric amount of epichlorohydrin. Then, we heated for 3 hours at a temperature of 80 ° C to promote the condensation of epichlorohydrin and the functions. The reaction is continued by adding subsequently a mass concentration of solution of 10% triethyl amine to the reaction mixture to obtain the closure of the oxirane ring. The reaction system at 60 ° C is brought under magnetic stirring for 60 minutes. The matrix of the DGECEPMMC resin is extract by the chloroform followed by water washing. The final resin is obtained after dissolution in chloroform followed by the vacuum evaporation method [16], we obtained a resin of brown color and an outcome of 82%.  3. Results and Discussions  3.1. the microscopic study of the synthesized epoxy resin: We performed the structural analysis of the epoxy resin obtained by the nuclear magnetic resonance of the proton (1 H NMR), carbon (13 C NMR) and confirmed the results by Fourier transform infrared spectroscopy and mass spectroscopy. the results of structural analyzes are given below.  Bekhta & al. / Mor. J. Chem. 3 N°3 (2015) 458-464  461  3.1.1. Fourier Transform Infrared (FTIR) The IR bands of the DGECEPMMC resin are shown in Figure 3.    Figure 3: Analysis of the resin DGECEPMMC by FTIR.  The allocation of the different peaks obtained by means of the infrared analysis in ATR mode are: FTIR (cm-1): 3300υ (residual OH), 2950 (CH of alkyl (CH3)), 2800, 1650 (C = O of ester), 1450.1400 (N- Amine) 1250.1200 (epoxide), 1103 (CS), 1038 (CO) of alcohols and ethers, (C-Cl).  3.1.2. Nuclear magnetic resonance (1 H NMR) The NMR spectra of the proton and the carbon of the DGECEPMMC resin are respectively shown in figure 4 and figure 5.  Figure 4: DGECEPMMC resin Analysis by NMR 1 H.  The NMR of the Proton (1H NMR) in ppm: 1.3 (s, 3H, CH3); 2.3 (t, 3H, CH3); 3.2-3.6 (m, 2H, CH2 Oxiranes); 5.3 (m, 2H, CH2-O); 4,4.5 (m, CH, oxiranes).  Bekhta & al. / Mor. J. Chem. 3 N°3 (2015) 458-464  462  3.1.3. Nuclear Magnetic Resonance (13 C)  Figure 5: Analysis of the resin by 13 C NMR DGECEPMMC.  The NMR of Carbon (NMR13C) ppm: 8 (S, CH2 linked to oxygen); 47 (S, CH3 linked to aromatic); 58.5-59 (S, CH oxiranes); 61-63 (S, CH2 linked to oxiranes) 64-66 (S, CH2 of oxirane); 57 (S, CH3 ester); 77 (s, aromatic CH); 138 (S, C tertiary, aromatic); 140 (S, C carbonyl, tertiary); 139 (S, carbon linked to chlorine); 137 (S, C linked to carbonyl, aromatic, tertiary); 136 (S, C tertiary, aromatic); 141 (S, CH, aromatic linked to nitrogen); 144 (S, C tertiary, aromatic, linked to sulfur).  3.2. Rheological studies of the standard DGECEPMMC resin As we mentioned previously, the rheological properties can be directly related to the chemical structure or the degree of conversion of the reagent system [9, 11, 14, and 15]. The rheological properties of the epoxy resin DGECEPMMC is studied by using a capillary viscometer of Ubbelohd type at varying temperatures going from 30 ° - 35 ° -40 ° to 45 ° C. Determining the viscometric behavior of the epoxy resin is thus made after preparing the system resin/solvent. We dissolved the resin in methanol at concentrations (5%, 10%, 15% and 20%), then studied their viscosity at the level of mass concentration by making a fixed temperature and at the level of the temperature by making the mass concentration of the resin/solvent system [14] .They are respectively shown in Figure 6 and Figure 7.  Figure 6: Effect of mass concentration on the viscosity of a system DGECEPMMC/methanol.  Bekhta & al. / Mor. J. Chem. 3 N°3 (2015) 458-464  463   Figure 7: Effect of temperature on the viscosity of a system DGECEPMMC/methanol.  In figure 6, the viscosity curves at the level of mass concentration in epoxy DGECEPMMC in methanol shows that the first value corresponding to the zero consultation refers to pure methanol. The results in this figure are all logical and expected: the viscosity of the solution increases as the polymer concentration (DGECEPMMC) increases. Figure 7 shows the curves of viscosity at the level of temperature and the different viscosity curves of the epoxy resin in methanol, at different temperatures, all having the same paces whatever the temperature is (up to 40 ° C). For this system we found that the viscosity values increase with temperature. We concluded from the two Figures 6 and 7 that: This shows the progress of the reaction of homopolymerization since the viscosity increases with the increase of molecular weight of the solute. This may be related to chemical transformations of the resin [12, 13]. At 45 ° C and 20% of mass concentration, the studied epoxy resin changes from a viscous state to a liquid state which explains the falling viscosity observed in both cases.  4. Conclusion: In this work we have synthesized a new bifunctional epoxy resin, at two stages. In the first one, we obtained the precursor molecule of the epoxy matrix (6- (4-chlorophenyl) -5-ethoxy-4-methyl-1,6-dihydropyrimine-2-thiol). the second one consisted in the functionalization of the latter with the epichlorohydrin. The microscopic characterization of the synthesized resin was confirmed by the microstructure study (Fourier transform infrared (FTIR and Nuclear Magnetic Resonance (NMR)) while the viscometric study gives the viscosity of the obtained bi-functional resin.  References:  [1] J. E. Mark, Phy Pr of Polymer H, Springer, (2007), 2e éd, 1076p.p. 294. [2] F. Nograro, F.de Guerrero, P. Corcuera, M.A. Mondragon, Appl. Polym. Sci., 56(1995), 177-192. [3] R.S. Bauer, S. Corley, in Ref Book for Co Tec, Lee, S.M. (Ed.), Technomic Publishing Co., Lancaster, (1989) 17-47. [4] S. Fetouaki,  A. Elharfi,  l. Belkebir.  J.  European.  Polymer. 38 (2002) 787–793. Bekhta & al. / Mor. J. Chem. 3 N°3 (2015) 458-464  464  [5] C.P. Wong, L. Wong, , Mater S.H.Shi. Res. Innovat.2(1999)232-247; [6] P. Castan, Brevet anglais, n°518,057 (1933). [7] J. Canadell, A. Mantecon, V. Cadiz, pol  Deg and stability, 92 (2007) 1934-1941. [8] Liu. Weichang, J. Varly Russell, P. Simon George, “polymer”, 48(2007)2351. [9] M.A. Mrkevich, Doct Dissertation, Cherngolovka, (1986). [10] S. Lipatov Yu, Moscow Khimiya, (1991). [11] P.G. De Genne, Polymer Phys, 1979. [12] I.Z. Chernin, F.M. Smekhov, M. Zherdyaev Yu, Moscow Khimiya, (1982). [13] A.N. Krasovskii, D.V. Novikov, V.N. Filippov, Zh. Prikl. Khim, 77(8)(2004) 1382-1388. [14] M. El Gouri, A. El Harfi, M. Rafik, S.E. Hegazi, M. Grich and H. Meghraoui, Ref. O241008/83. Ph&Ch News (2009). [15] R. Ziraoui, M. Grich, H. Meghraoui, A. Elharfi, Ann. Chil. Sci. Mat., 35 (2010) 99-112. [16] H. Meghraoui, N. Rami, M. Toufik, A. Elharfi, Phys. Chem. News 38 (2007) 84-92. [17] P. Biginelli, Gazz. Chim. Ital. 23(1893) 360−413. [18] S. Maddila and S. B. Jonnalagadda. Bull. Chem. Soc. Ethiop., 26(1)(2012) 121-126.  

Synthesis, viscometric and microscopic characterization of a new bifunctional sulfur epoxy resin.

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Synthesis, viscometric and microscopic characterization of a new bifunctional sulfur epoxy resin.

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