Elaboration of new epoxy resin octafonctionnelle by chemical modification of the DGEBA. Study of the rheologic parameter

338

Elaboration of new epoxy resin octafonctionnelle by chemical modification of the DGEBA. Study of the rheologic parameter

J. El Azzaoui*, N. El-Aouni, A. Bekhta, A. El Harfi

Polymers Laboratory, Radiation and Environment (TPA), Team of Organic and Macromolecular Chemistry (ECOM), Department of Chemistry, Faculty of Science, University Ibn Tofail, BP133, 14000, Kenitra, Morocco

*Corresponding Author. E-mail: Jalilaelazzaoui@gmail.com Received 25 Jan 2014, Revised 10 Fev 2015, Accepted 05 Mars 2015

Abstract

The objective of our work is to synthesize a new octafunctional epoxy resin in two steps. In the first step we obtained the DGEBA with bisphenol A. The second step, leading to the synthesis of an octafunctional resin by the action of a nucleophile on the DGEBA is not evident by the conventional route. The latter would require several steps with various monomers certainly low. Firstly, microscopic characterization was obtained by using the Fourier Transform Infrared (FTIR), and nuclear magnetic resonance (NMR) ¹H and

13C. The characterization of this new viscosimetric octafunctional resin was evaluated on the other hand.

Keywords: Epoxy Resin Octafunctional, DGEBA, Microscopic and Viscometric Characterizations.

1.

Introduction

Polymers are now widely used in industry [1]. They exist tings of insulation materials in electrical equipment and devices for example generators, transformers, high voltage instruments, wiring loom, coating components and etc. They also exist in fourme glues, varnishes and paints applied in the field of aviation [2]

and the metal coating and / or road [3] and etc. Among these polymeric materials include those epoxy resins which are the subject of our study, since they constitute a growing interest in scientific research and also in industrial production because of their thermal, electrical and rheological [4-5-6] which are very remarkable.

Thermosetting resins include polyepoxides are matrices with excellent high performance macromolecules used in standard or composite form in various industrial sectors. [7] The thermal properties of such resins depend mainly on their chemical structure, as provided by their aromatic nuclei, as well as the adhesion, the corrosion resistance and the rigidity are provided respectively by the hydroxyl functions and of the cores bisphenol such resins, while their resistance to hydrolysis is due to ether bridges [8]. Epoxy resins or polyepoxides are also called prepolymers based molecules having several epoxy functions which can be bi- or tri or tetra or octafonctionnelles [9-10-11-12]. These resins are generally synthesized by the polycondensation reaction at different steps.

In this study, we initially synthesized a new octafunctional epoxy resin whose name is octaglycidyle dihydrazine dipropoxy para-bisphenol A (OGDHDPBA) and/or with the following systematic nomenclature:

bis [3 (N, N, N 'Tri (2, 3-epoxy propyl)) hydrazine, 2-glycidyl ether] -O-propyl para-bisphenol A, and then,

339 we looked at the microscopic characterization of the resin obtained by the infrared Fourier Transform (FTIR), the nuclear magnetic resonance (NMR), and the rheological property of viscosity since it plays a crucial role in the case of the organic matrix flow and it is based mainly on the influence of temperature and resin / solvent system.

2. Materials and Methods

2.1. The materials used

The basic products are bisphenol A in powder, epichlorohydrin with a purity of 99%, hydrazine stored at a temperature of 4 to 6 °C. These commodities have been provided by the companies Acros Chemical Co. and Aldrich Chemical Co. with no further purification.

2.2. Synthesis of epoxy resins

In this study, we present the two stages of the synthesis of a new epoxy resin Octaglycidyle dihydrazine dipropoxy Para Bisphenol A (OGDHDPBA) according to the following The OGDHDPBA resin was synthesized according to the following steps:

Figure 1. Schematic synthesis of octaglycidyle dihydrazine dipropoxy of bis-para-phenol A.

2.2.1. First step: preparation of diglycidylether of bisphenol A (DGEBA)

Epichlorohydrin reacts with Bisphenol A, noted in this study of compound 1, as a starting material in the presence of sodium hydroxide to obtain the compound 2 according to the method described by P. Castant [13].

2.2.1.1. Procedure

In a two-necked flask fitted with a condenser and a dropping funnel, we placed 4.2 × 10^-3 mol of Bisphenol A (compound 1) and 8.13 × 10^-3 mol of epichlorohydrin. After complete dissolution of the bisphenol A, the resulting mixture was heated to 100 °C for 3 hours with magnetic stirring. We then cooled it to 60 °C and added, via a dropping funnel, 5.5g of a solution of soda by 50% in mass. The prepared reaction mixture was stirred for 40 minutes (always at 60 °C). Finally, water was added to the mixture to separate the aqueous phase from the organic chloroform then we dried the latter by Na₂SO₄ and evaporated it under vacuum [13- 14-15]. Performance and physicochemical characteristics of the DGEBA obtained are recorded in Table 1.

340 2.2.2 Second step: preparing OGDHDPBA

Hydrazine action on DGEBA as a nucleophile to open epoxides cycles of OGEDHDPBA. The opening of the epoxy cycle by the primary amine groups of the hydrazine according to the method described by Smith, Horie et al [16-17-18] is carried out by the formation of complexes based on hydrogen bonds, in particular the association of hydroxyl groups with epoxy to come up with a type of complex (CH (OH) -CH₂-) [19-20].

The primary amine protons can thus be formed creating this type of complexes (Figure 2). Other types of impurities givers of proton (HX) can catalyze the cycle opening conducted to the formation of the compound 3. The action of the hydroxyl group obtained with epichlorohydrin has led us to obtain the compound 4.

Figure 2. Diagram of the epoxides’ opening.

2.2.2.1 Procedure

This method tends to condense 4.38 × 10^-3 mol of DGEBA and 7.98 × 10^-3 mol of hydrazine in 25 ml of a methanol. The solution of the mixture is brought to a temperature of 90 ° C for 4 h to give the compound 3.

After 4 h the solution is then cooled to 60 ° C. we add to the reaction mixture 3.5 × 10^-2 mol of

epichlorohydrin (in excess) while adding friend triethyl (NEt₃). The mixture is brought to a temperature of 60 °C for 3 hours to obtain the product 4 (OGEDHDPBA). The performance and the physico-chemical characteristics of the OGEDHDPBA are shown in Table 1.

Table 1. Performance and physic-chemical characteristics of DGEBA and OGEDHDPBA.

Product Empirical Formula Molar Mass (g/mol)

performance % Aspect

DGEBA C₂₁H₂₄O₄ 340-342 75% viscous

whitish

DGEDHDPBA C45H64N4O12 852-854 89% brown

viscous

2.3. Analytical Methods

2.3.1. Fourier Transform Infrared (FTIR)

The IR spectrometer used is an infrared spectroscopy of Fourier Transform (FTIR) BRUKER. The tapes were obtained by transmission on total attenuated reflection (ATR Attenuated Total Reflectance). The spectral range corresponding to molecules vibrating energies between 2.5 and 25 microns. The analysis was made between 600 cm^-1 and 4000 cm^-1.

2.3.2. Nuclear magnetic resonance (NMR)

The NMR ¹H and ¹³C analyzes were obtained using a device called AVANCE 300MHz of Bruker, by dissolving the product in DMSO. Chemical shifts are expressed in ppm, coupling constants in Hz and the following abbreviations have been used: s, d, dd, t, q and m respectively mean singlet, doublet, doubled doublet, triplet, quadruplet and multiplet.

341 2.3. 3. viscometric analysis

The reactivity of epoxy storage systems was controlled with the aid of a viscometer type UBBELOHDE VB-1423.

Selected measuring conditions are as follows:

 Viscometer of 1B size for a series of dilution, capillary tube diameter of 0.46 mm, constant k= 0.051493.

 Measuring temperature in °C: 25 up to 75

 Number of measurement: 5 every time

 Solvent: Methanol

 Hagenbach correction was calculated using the formula given in the DIN 1999 standard 51562-1 Janvier (Measurement of kinematic viscosity by means clustering of the Ubbelohde viscometer)

 Solubilizing epoxy resin pre-polymers in methanol was carried out under magnetic stirring at 20 °C.

Figure 3. Viscometric measurements apparatus.

3. Results and Discussion

3.1. Spectral characterization of the synthesized epoxy resins

We performed the structural analysis of the products obtained by means of nuclear magnetic resonance of the proton (¹H NMR), carbon (¹³C) and confirmed the results by Fourier Transform infrared spectroscopy (FTIR). The results of structural analyzes given below have confirmed the epoxy resin structure synthesized.

3.1.1. The structural study by FTIR

3.1.1.1. Diglycidyl ether of bisphenol A (DGEBA)

IRTF (cm^-1): 910-830(epoxy); 3040-1600-760(aromatic); 2900-1450 (C-H methylene); 1230 (Ar-O); 1030- 1090-1180 (C-O alcohols and ethers); 3340(OH residual) [21].

3.1.1.2. Octaglycidyle dihydrazine dipropoxy of bis-para-phenol A

Figure 4 shows the Octaglycidyle dihydrazine dipropoxy resin bands of bis-para-phenol A obtained by FTIR whose allocation is described below:

342 Figure 4. IR spectrum of OGDHDPBA.

840-850 (C-H de –CH-, Sym deformation of oxirane); 920( C-H de –CH-, Sym deformation oxirane); 990- 1050-1090 ( δ C-Har, aromatic CH elongation); 1200 (ν C-N); 1250 (ν Car-O-Alkyl: aromatic ether and epoxy ν COC); 1375 (δC-Car tertiary carbon); 1400-1410(δC-H Epoxy / ether) ; 1470 (δC-H δCH2 epoxide or methylene linked to the oxirane ring); 1500-1610(ν Car=Car aromatic of para-substituted benzene cycle) ; 2870(νs CH2 methylene ether); 2970 (νas CH2 methylene ether); 3380 (ν OH).

3.1.2. Structural study by NMR

3.1.2.1. Diglycidyl ether of bisphenol A (DGEBA)

RMN ¹H (ppm): 2,8 (m, 2H, CH₂); 3,3 (m, 1H, CH oxirane);4,1 (dd; OCH₂); 7-7,6 (Classic AB system, 4H aromatic).

RMN ¹³C (ppm): 34,9 (s, CH₃); 42,1 (s, CH₂ oxirane);45 (s, C tertiary); 50,9(s, CH oxirane); 71,1(s, CH₂ ether); 112,3 (s, CH aromatic); 156,6(s, C aromatic tertiary linked to oxygen); 32,4(s, CH aromatic);

143,1(s, C aromatic tertiary) [21].

3.1.2.2. Octaglycidyle dihydrazine dipropoxy bis-para-phenol A

Figures 6 and 7 respectively show the spectra of the proton and Octaglycidyle dihydrazine dipropoxy resin atoms of the bis-para-phenol A obtained by NMR whose attribution is described below:

Figure 5. Diagram of the OGDHDPBA structure.

343 Figure 6. The spectrum 1 H NMR of the OGDHDPBA.

Figure 7. The spectrum 13C NMR of the OGDHDPBA.

RMN ¹H (ppm): 1,57 (s, 3H₉, CH₃); 3,20(dd, 2H1’, CH₂oxirane); 3,26 (dd, 2H₁, CH₂ oxirane); 3,60 (m, H2’,CH oxirane); 3,65 (m, H2, CH oxirane); 3,70(m, 1H4, CH ); 3,90 (dd, 2H3’, CH2 linked to nitrogen);

4,05 (dd, 2H3, CH₂ linked to nitrogen); 5,36 (dd, 2H₅,OCH₂-époxy); 5,57 (dd, 2H₆, CH₂ linked to oxygen);

6,8 (d, 1H8, CH aromatic) ; 7,1(d, 1H7, CH aromatic).

RMN ¹³C (ppm): 31,5 (S, CH3a); 46,75 (S, CH2b’oxirane-CH2-N); 47(s, CH2b oxirane-CH2-O); 47,7 (S, CH2f linked to nitrogen);58,5 (S, Cd tertiary); 63,5 (S, CH2f’ linked to nitrogen);68,4 (S, CHC’ oxirane linked to nitrogen);71 (S, CHc linked to oxygen);72 (S, CHe ether linked to oxygen); 114,5 (S, CHi aromatic); 127 (S, CHj aromatic); 143,5 (S, Ck aromatic tertiary linked to carbon); 156,5 (S, CHl aromatic tertiary linked to oxygen).

3.2. Study of the viscosimetric OGDHDPBA

As we mentioned previously, the rheological properties can be directly related to the chemical structure or the degree of conversion of the reactive system [12-15-22-23]. To determine the viscometric [24-25-26]

behavior of OGDHDPBA, we dissolved the resin in methanol concentration of 5%, 10%, 15% and 20% at various temperatures going from 25 ° to 75 °.

344 Figure 8 shows the study of the mass concentration effect on the viscosity OGEDHDPBA / methanol of resin Octaglycidyle dihydrazine dipropoxy of bis-para-phenol A:

4 6 8 10 12 14 16 18 20 22

0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00 1,05 1,10 1,15 1,20 1,25 1,30

Viscosity

Concentration(peurcentage massique)

25°C 30°C 35°C 40°C 45°C 50°C 55°C 60°C 65°C 70°C 75°C

Figure 8. Effect of mass concentration on the viscosity OGEDHDPBA / methanol.

Through the obtained curves of viscosity, we noticed that the viscosity values increase with the concentration. This shows the progress of the reaction of the homo-polymerization since viscosity increases with increasing molecular weight of the solute. This may be related to the chemical transformations of the resin [12-27-28]. We can expect the following actions:

 The addition of epichlorohydrin was not complete because of the steric hindrance of the NH2 groups of the hydrazine;

 The reactivity of the tertiary amine vis-à-vis the epoxide function under the effect of temperature;

 The intervention of opening reactions of the regenerated epoxide cycles;

All these factors may influence the functionality of the obtained product. Therefore we would have the residual amines and hydroxyl which are presenting labile protons, which may be responsible for a self- crosslinking of the pre-polymer by adding the hardener [12, 22, 28].

4. Conclusion

In this work, we presented the synthesis and structural characterization of the new epoxy resin "the octaglycidyle dihydrazine dipropoxy bis-para-phenol A". The synthesis of this macromolecular matrix has been obtained by the chemical modification of DGEBA with hydrazine in an ideal performance. The structure of this resin was confirmed and characterized by the usual spectroscopic methods FTIR, ¹H and ¹³C NMR. The viscometric study allowed us to show that the bisphenol resin of synthesized octa-glycidyl type OGEDHDP, has the disadvantage of self-crosslinking. It is manifested by an increase in viscosity hence their storage at low temperatures.

References

[1] M. Książek, Compos. Part B: Engine., 58 (2014) 378-385.

[2] O. Gohardani, D. M. Williamson, D. W. Hammond, J. Wear., 294–295 (2012) 336-346.

[3] J. J. Santana, J. González-Guzmán, J. Izquierdo, S. González, R. M. Souto, J. Corro. Sience., 52 (2010) 3924-3931.

[4] P. Tsotra, K. Friedrich, J. Synthetic. Metals., 143 (2004) 237-242.

345 [5] H. Germazi, H. Smaoui, S. Agnel, Y. Mlik, A. Toureille, F. Schue, J. Polym. Int., 50 (2001) 743-747.

[6] S. Chraibi, M. Allouch, F. Boukhlifi, M. Alami, Mor. J. Chem., 2 (2014) 490-493.

[7] N. N. Ghosh, B. Kiskan, Y. Yagci, J. Progress in Polymer Science., 32 (2007) 1344-1391.

[8] C. Barrere, F. Dal-Maso, Oil and Gas Science and Technology., 52 (1997) 317-335.

[9] S. Fetouaki, A. El Harfi, L. Belkebir, J. European Polymer., 38 (2002) 787-793.

[10] J. Canadell, A. Mantecon, V. Cadiz, J. Polymer Degradation and Stability., 92 (2007) 1934-1941.

[11] L. Weichang, J. Varley Russell, S. George, J. Polymer, P., 48 (2007) 2345-2354.

[12] M. El Gouri, A. El Harfi, M. Rafik, S. E. Hegazi, M. Grich, H. Meghraoui, J. Phys. Chem. News., 52 (2010) 112-128.

[13] C. P. Wong, L. Wang, S. H. Shi, J. Mater. Res. Innovat., 2(1999) 232-247.

[14] H. Meghraoui, N. Rami, M. Toufik, A. El Harfi, J. Phys. Chem. News., 38 (2007) 84-92.

[15] R. Zirauoi, M. Grich, H. Meghraoui, A. El Harfi, J. Ann. Chil. Sci. Mat., 35 (2010) 99-112.

[16] I. T. Smith, J. Applied. Polymer. Science., 42 (1991) 2453–2463.

[17] K. Horie, M. Hiura, H. Sawada, I. Mita, H. Kambe, J. Polymer. Science. Chemistry., 8 (1970) 1357–

1372.

[18] M. El Gouri, A. El Harfi, J. Mater. Environ. Sci., 3 (2012) 17-33.

[19] B. A. Rozenberg, J. Advances. Polymer. Science., 75 (1986) 113-165.

[20] R. Mezzenga, L. Boogh, J. A. E. Manson, B. Pettersson, J. Macromolecules., 33 (2000) 4373-4379.

[21] R. Ziraoui, H. Meghrauoi, N. Rami, O. Cherkaoui, A. M. Choukri, O. K. Hakam, A. El Harfi, J. Ann.

Chil. Sci. Mat., 37 (2012) 85-96.

[22] P. G. De-Genne, J. Chem. Phys., 49 (1968) 1032-1035.

[23] J. El Azzaoui, M. Rafik, S. E. Hegazi, A. El Harfi, Inter. J . Innov. Appl. Stud., 7 (2014) 883-891.

[24] L. Tennouga, A. Mansri, Mor. J. Chem, 2 (2014) 415-420.

[25] M. El Gouri, A. El Mansouri, R. El Gouri, N. Hadik, O. Cherkaoui, A. Outzourhit, A. El Harfi, J.

Mater. Environ. Sci. 5 (2014) 400-407.

[26] M. Grich, M. El Gouri, R. Ziraoui, N. Rami, H. Meghraoui, O. Cherkaoui, A. El Harfi, J. Mater.

Environ. Sci. 5 (2014) 374-379.

[27] I. Z. Chernin, F. F. M. Smekhov, M. Yu, J. Applied. Chemistry., 79 (2006) 1673-1680.

[28] A. N. Krasovskii, D. V. Novikov, V. N. Filippov, P. Khim., Russi. J. of Appli. Chemis. 77 (2004) 1382-1388.