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Epoxy Resins Cross-Linked with Bisphenol A/Methylenedianiline Novolac Resin Type / Fanica R. Mustata in Industrial & engineering chemistry research, Vol. 51 N° 25 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 25 (Juin 2012) . - pp. 8415–8424 Titre : Epoxy Resins Cross-Linked with Bisphenol A/Methylenedianiline Novolac Resin Type : Curing and Thermal Behavior Study Type de document : texte imprimé Auteurs : Fanica R. Mustata, Auteur ; Nita Tudorachi, Auteur ; Ioan Bicu, Auteur Année de publication : 2012 Article en page(s) : pp. 8415–8424 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Thermal  behavior Résumé : A novolac type resin was synthesized from bisphenol A, 4,4′-methylenedianiline, and formaldehyde in the presence of HCl. The chemical structure was confirmed using elemental analysis, FT-IR spectroscopy, and 1H NMR spectroscopy. The curing kinetics of these epoxy resins at an epoxy ring/amine proton molar ratio of 1/1, were studied by nonisothermal differential scanning calorimetry (DSC) at different heating rates. The kinetic analysis of the curing reactions was evaluated using the variable peak exotherm method of Flynn–Wall–Ozawa and Kissinger. The thermal degradation mechanisms for novolac resin (FR) and cured resins were identified taking place between two and four steps, depending on the chemical structure of the sample. The most probable kinetic model and kinetic parameters of the degradation process were estimated using Netzsch Thermokinetics software. The cured resins have good thermal stability, with activation energies of thermal degradation reactions having values situated in the range 127–184 kJ·mol–1. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202909s [article] Epoxy Resins Cross-Linked with Bisphenol A/Methylenedianiline Novolac Resin Type : Curing and Thermal Behavior Study [texte imprimé] / Fanica R. Mustata, Auteur ; Nita Tudorachi, Auteur ; Ioan Bicu, Auteur . - 2012 . - pp. 8415–8424. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 25 (Juin 2012) . - pp. 8415–8424 Mots-clés : Thermal  behavior Résumé : A novolac type resin was synthesized from bisphenol A, 4,4′-methylenedianiline, and formaldehyde in the presence of HCl. The chemical structure was confirmed using elemental analysis, FT-IR spectroscopy, and 1H NMR spectroscopy. The curing kinetics of these epoxy resins at an epoxy ring/amine proton molar ratio of 1/1, were studied by nonisothermal differential scanning calorimetry (DSC) at different heating rates. The kinetic analysis of the curing reactions was evaluated using the variable peak exotherm method of Flynn–Wall–Ozawa and Kissinger. The thermal degradation mechanisms for novolac resin (FR) and cured resins were identified taking place between two and four steps, depending on the chemical structure of the sample. The most probable kinetic model and kinetic parameters of the degradation process were estimated using Netzsch Thermokinetics software. The cured resins have good thermal stability, with activation energies of thermal degradation reactions having values situated in the range 127–184 kJ·mol–1. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202909s

Epoxy resins cross - linked with rosin adduct derivatives. cross - linking and thermal behaviors / Fanica R. Mustata in Industrial & engineering chemistry research, Vol. 49 N° 24 (Décembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12414-12422 Titre : Epoxy resins cross - linked with rosin adduct derivatives. cross - linking and thermal behaviors Type de document : texte imprimé Auteurs : Fanica R. Mustata, Auteur ; Nita Tudorachi, Auteur Année de publication : 2011 Article en page(s) : pp. 12414-12422 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Rosin  adduct  derivatives Résumé : Rosin adduct derivatives were obtained by chemical reaction of the Diels—Alder adduct of rosin acid with maleic anhydride (RAMA) with aspartic acid (ASP) and p-aminobenzoic acid (p-ABA), at 1/1 molar ratio. The structure of the obtained monomers was established by means of elemental analysis, FT-IR spectroscopy, and 1H NMR. These acids were used as cross-linking agents, in the presence of triethylbenzylammonium chloride as catalyst (TEBAC) for diglycidyl monomers (diglycidyl ether of bisphenol A, DGEBA, and diglycidyl ether of hydroquinone, DGEHQ). Using differential scanning calorimetry (DSC) at different heating rates and the literature methods, the kinetic parameters of cross-linking reactions were obtained. The thermal stability of the cross-linked polymers investigated by using thermogravimetric analysis (TGA) showed they are reasonably thermostable. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101746v [article] Epoxy resins cross - linked with rosin adduct derivatives. cross - linking and thermal behaviors [texte imprimé] / Fanica R. Mustata, Auteur ; Nita Tudorachi, Auteur . - 2011 . - pp. 12414-12422. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12414-12422 Mots-clés : Rosin  adduct  derivatives Résumé : Rosin adduct derivatives were obtained by chemical reaction of the Diels—Alder adduct of rosin acid with maleic anhydride (RAMA) with aspartic acid (ASP) and p-aminobenzoic acid (p-ABA), at 1/1 molar ratio. The structure of the obtained monomers was established by means of elemental analysis, FT-IR spectroscopy, and 1H NMR. These acids were used as cross-linking agents, in the presence of triethylbenzylammonium chloride as catalyst (TEBAC) for diglycidyl monomers (diglycidyl ether of bisphenol A, DGEBA, and diglycidyl ether of hydroquinone, DGEHQ). Using differential scanning calorimetry (DSC) at different heating rates and the literature methods, the kinetic parameters of cross-linking reactions were obtained. The thermal stability of the cross-linked polymers investigated by using thermogravimetric analysis (TGA) showed they are reasonably thermostable. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101746v

Thermal degradation of carboxymethyl starch–g-poly(lactic acid) copolymer by TG–FTIR–MS analysis / Nita Tudorachi in Industrial & engineering chemistry research, Vol. 51 N° 48 (Décembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 48 (Décembre 2012) . - pp. 15537–15545 Titre : Thermal degradation of carboxymethyl starch–g-poly(lactic acid) copolymer by TG–FTIR–MS analysis Type de document : texte imprimé Auteurs : Nita Tudorachi, Auteur ; Rodica Lipsa, Auteur ; Fanica R. Mustata, Auteur Année de publication : 2013 Article en page(s) : pp. 15537–15545 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Carboxymethyl  starch Résumé : In this study, carboxymethyl starch (CMS) was grafted with l(+)-lactic acid (LA) in a CMS/LA molar ratio of 1/36, resulting in the CMS–g-PLA copolymer. The grafting reaction was carried out via a solution polycondensation procedure, in the presence of stannous 2-ethyl hexanoate [Sn(Oct)2] as a catalyst. Poly(lactic acid) (PLA) was synthesized under the same conditions with the copolymer, for comparative analyses of the thermal properties. The CMS–g-PLA copolymer, CMS, and PLA were structurally characterized by Fourier transform infrared (FTIR) spectroscopy, while thermal degradation products were characterized by thermogravimetry analysis coupled with Fourier transform infrared spectroscopy and mass spectrometry (TG–FTIR–MS). The thermal degradation was achieved in a nitrogen atmosphere, in a temperature interval of 30–600 °C. The thermal degradation of CMS and PLA was studied under the same conditions to highlight the products resulted by the thermal decomposition of CMS–g-PLA copolymer. By processing the achieved data via thermal degradation at three different heating speeds (5, 7.5, and 10 °C min–1) and using the multivariate nonlinear regression method (MNLR), the kinetic parameters were determined. The dependence of the activation energy of the degradation process versus the extent of conversion was evaluated using the Friedman and Ozawa–Flynn–Wall model-free analyses. This variation suggests that the degradation process is a complex one and can be divided in one or two steps, depending on the chemical structure of the compounds. The kinetic parameters and the most probable thermal degradation mechanisms were given. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300625c [article] Thermal degradation of carboxymethyl starch–g-poly(lactic acid) copolymer by TG–FTIR–MS analysis [texte imprimé] / Nita Tudorachi, Auteur ; Rodica Lipsa, Auteur ; Fanica R. Mustata, Auteur . - 2013 . - pp. 15537–15545. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 48 (Décembre 2012) . - pp. 15537–15545 Mots-clés : Carboxymethyl  starch Résumé : In this study, carboxymethyl starch (CMS) was grafted with l(+)-lactic acid (LA) in a CMS/LA molar ratio of 1/36, resulting in the CMS–g-PLA copolymer. The grafting reaction was carried out via a solution polycondensation procedure, in the presence of stannous 2-ethyl hexanoate [Sn(Oct)2] as a catalyst. Poly(lactic acid) (PLA) was synthesized under the same conditions with the copolymer, for comparative analyses of the thermal properties. The CMS–g-PLA copolymer, CMS, and PLA were structurally characterized by Fourier transform infrared (FTIR) spectroscopy, while thermal degradation products were characterized by thermogravimetry analysis coupled with Fourier transform infrared spectroscopy and mass spectrometry (TG–FTIR–MS). The thermal degradation was achieved in a nitrogen atmosphere, in a temperature interval of 30–600 °C. The thermal degradation of CMS and PLA was studied under the same conditions to highlight the products resulted by the thermal decomposition of CMS–g-PLA copolymer. By processing the achieved data via thermal degradation at three different heating speeds (5, 7.5, and 10 °C min–1) and using the multivariate nonlinear regression method (MNLR), the kinetic parameters were determined. The dependence of the activation energy of the degradation process versus the extent of conversion was evaluated using the Friedman and Ozawa–Flynn–Wall model-free analyses. This variation suggests that the degradation process is a complex one and can be divided in one or two steps, depending on the chemical structure of the compounds. The kinetic parameters and the most probable thermal degradation mechanisms were given. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300625c