Curing and thermal behaviour of epoxy resin in the presence of a mixture of imide-amines (original) (raw)
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Curing and thermal behaviour of epoxy resin in the presence of aromatic imide-amines
Indian Journal of Engineering and Materials Sciences, 2005
The paper describes the synthesis and characterization of aromatic imide-amines obtained by reacting pyromellitic dianhydride (P)/or benzophenone 3,3′, 4,4′-tetracarboxylic dianhydride (B) (1 mol) with excess of 4,4′-diaminodiphenyl ether [E]/or 4,4′-diaminodiphenyl methane [M]/or 4,4′-diaminodiphenyl sulfone [S] and their use as curing agents for diglycidyl ether of bisphenol-A (DGEBA). Structural characterization of imide-amines was done using FTIR, 1 H-NMR, 13 C-NMR spectroscopy and elemental analysis. These aromatic imide-amines were used as curing agents in order to investigate the effect of structure on the curing and thermal behaviour of diglycidyl ether of bisphenol-A (DGEBA). Curing behaviour of DGEBA in the presence of stoichiometric amounts of aromatic imide-amines was investigated by differential scanning calorimetry (DSC). A broad exothermic transition in the temperature range of 180-230°C was observed in all the samples. The peak exotherm temperature (T p) was lowest in case of imide-amines based on B and M and highest in case of imide-amines based on P/or B and S. Thermal stability of the isothermally cured resins was investigated using dynamic thermogravimetry in nitrogen atmosphere. The char yield was highest for resin cured with imide-amines based on B and E.
Curing of epoxy resin using imide-amines
Journal of Applied Polymer Science, 2006
The curing behavior of diglycidyl ether of bisphenol-A (DGEBA) was investigated by differential scanning calorimetry, using varying molar ratios of imide-amines and 4,4′-diaminodiphenyl sulfone (DDS). The imide-amines were prepared by reacting 1 mol of pyromellitic dianhydride (P) with excess (2.5 mol) of 4,4′-diaminodiphenyl ether (E), 4,4′-diaminodiphenyl methane (M), or 4,4′-diaminodiphenyl sulfone (S) and designated as PE, PM, PS. Structural characterization was done using FTIR, 1H NMR, 13C NMR spectroscopic techniques and elemental analysis. The mixture of imide-amines and DDS at ratio of 0 : 1, 0.25 : 0.75, 0.5 : 0.5, 0.75 : 0.25, and 1 : 0 were used to investigate the curing behavior of DGEBA. The multiple heating rate method (5, 10, 15, and 20°C/min) was used to study the curing kinetics of epoxy resins. The peak exotherm temperature was found to be dependent on the heating rate, structure of imide-amine, and also on the ratio of imide-amine : DDS used. Activation energy was highest in case of epoxy cured using a mixture of DDS : imide-amine of a ratio of 0.75 : 0.25. Thermal stability of the isothermally cured resins was also evaluated in a nitrogen atmosphere using dynamic thermogravimetry. The char yield was highest in case of resins cured using mixture of DDS : PS (0.25 : 0.75; EPS-3), DDS : PM (0.25 : 0.75; EPM-3), and DDS : PE (0.75 : 0.25; EPE-1). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3502–3510, 2006
Curing kinetics and thermal stability of diglycidyl ether of bisphenol
Journal of Thermal Analysis and Calorimetry, 2008
Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of varying molar ratios of aromatic imide-amines and 4,4′-diaminodiphenylsulfone (DDS) were investigated by the dynamic differential scanning calorimetry. The imide-amines were prepared by reacting 1 mole of benzophenone 3,3′,4,4′-tetracarboxylic acid dianhydride (B) with 2.5 moles of 4,4′-diaminodiphenyl ether (E)/ or 4,4′-diaminodiphenyl methane (M)/ or 4,4′-diaminodiphenylsulfone (S) and designated as BE/ or BM/ or BS. The mixture of imide-amines and DDS at ratio of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 were used to investigate the curing behaviour of DGEBA. The multiple heating rate method (5, 10, 15 and 20°C min−1) was used to study the curing kinetics of epoxy resins. The peak exotherm temperature was found to be dependent on the heating rate, structure of imide-amines as well as on the ratio of imide-amine: DDS used. A broad exotherm was observed in the temperature range of 180–230°C on curing with mixture of imide-amines and DDS. Curing of DGEBA with mixture of imide-amines and/or DDS resulted in a decrease in characteristic curing temperatures. Activation energy of curing reaction as determined in accordance to the Ozawa’s method was found to be dependent on the structure of amine. The thermal stability of the isothermally cured resins was also evaluated using dynamic thermogravimetry in a nitrogen atmosphere. The char yield was highest in case of resins cured using mixture of DDS: BS (0.25:0.75; EBS-3), DDS: BM (0.5: 0.5; EBM-2) and DDS: BE (0.5: 0.5; EBE-2).
Curing and thermal behavior of DGEBA in presence of dianhydrides and aromatic diamine
Journal of Applied Polymer Science, 2007
The article describes the curing behavior of diglycidyl ether of bisphenol-A using benzophenone 3,3 0 , 4,4 0-tetracarboxylic acid dianhydride (BTDA)/naphthalene 1,4,5,8-tetracarboxylic dianhydride (NTDA)/or mixture of BTDA and 4,4 0-diaminodiphenyl sulfone (DDS)/ or NTDA and DDS in varying molar ratio as curing agent. Differential scanning calorimetry was used to investigate the cure kinetics by recording DSC scans at heating rates of 5, 10, 15, and 20 8C/min. The peak exotherm temperature was found to be dependent on the heating rate, structure of the dianhydride as well as on the DDS/dianhydride molar ratio. Activation energy of curing reaction as determined in accordance to Ozawa's method was found to be dependent on the structure of anhydride as well as on the ratio of anhydride to amine. Thermal stability of the isothermally cured resins was evaluated using dynamic thermogravimetry in nitrogen atmosphere. The char yield was highest in case of resins cured using DDS/BTDA mixture or DDS/ NTDA one (0.75 : 0.25; sample EB-1/or EN-1).
Polymer International, 2003
The curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) was investigated by differential scanning calorimetry using bis(4-carboxyphenyl) dimethyl silane (CPA) as a crosslinking agent and imidazole as a catalyst. Two exotherms were observed in the absence of catalyst in the temperature range 166-328 • C. A significant decrease in the curing temperature was observed when 0.1% imidazole was used as catalyst. Further increase in the concentration of imidazole resulted in a decrease in the peak exotherm temperature. The effect of stoichiometry of functional groups on the curing behaviour of DGEBA was investigated by taking varying mole ratios of CPA, ranging from 1 to 2.5, keeping the concentration of imidazole as 0.1% w/w. The heat of polymerization ( H) was found to be maximum at a molar ratio of 1:1.75 (DGEBA:CPA). Mixtures of diaminodiphenyl sulfone (DDS and CPA or phthalic anhydride (PA) and CPA in ratios of 1:0, 0.25:0.75, 0.5:0.5, 0.75:0.25) were also used to investigate the curing behaviour of DGEBA. A significant decrease in curing temperature of DGEBA/DDS was observed on partially replacing DDS with CPA, whereas marginal change in the curing temperatures was observed on replacing phthalic anhydride with CPA. The thermal stability of epoxy resin, cured isothermally, was evaluated by recording thermogravimetry/dynamic thermogravimetry traces in nitrogen atmosphere. The percentage char yield was highest for the sample cured using 1.75 mole of CPA.
Journal of Applied Polymer Science, 2008
The curing behavior of diglycidyl ether of bisphenol-A (DGEBA) with aromatic imide–amines having aryl ether, sulfone, and methylene linkages was studied using differential scanning calorimetry (DSC). Six imide–amines of varying structure were synthesized by reacting 1 mol of naphthalene 1,4,5,8-tetracarboxylic dianhydride (N) or 4,4′-oxodiphthalic anhydride (O) with excess (>2 mol) of 4,4′-diaminodiphenylether [E] or 4,4′-diaminodiphenyl methane [M] or 4,4′-diaminodiphenyl sulfone [S]. The imide–amines prepared by reacting O or N with S, M, and E have been designated as OS/NS; OM/NM, and OE/NE, respectively. Structural characterization of imide–amines was done using FTIR, 1H NMR, 13C NMR, and elemental analysis. The curing behavior of DGEBA in the presence of stoichiometric amount of imide–amines was investigated by recording DSC scans. A broad exothermic transition was observed and the peak exotherm temperature was found to be dependent on the structure of imide–amines. The peak exotherm temperature (Tp) was lowest in case of imide–amines OE and highest in case of imide–amines NS/OS. Thermal stability of isothermally cured DGEBA in the presence of imide–amines was evaluated by dynamic thermogravimetry. The char yield was highest for resin cured with imide–amines NE. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Journal of Applied Polymer Science, 2007
The curing behaviour of DGEBA was investigated by differential scanning calorimetry in the presence of varying amounts of PMDA. The molar ratio of DGEBA : PMDA was varied as 1 : 0.8, 1 : 1, 1 : 1.5, 1 : 2.0, and 1 : 2.5. The heat of polymerization (DH) was found to be maximum at a molar ratio of 1 : 0.8 (DGEBA : PMDA). To study the effect of imidazole content on the curing behaviour, varying amounts of imidazole, i.e., 0.1, 0.15, 0.2, and 0.3% (w/w) were used keeping the ratio of DGEBA : PMDA (1 : 0.8) constant. A broad exotherm was observed in all the samples. A significant decrease in the peak exotherm was observed when 0.1% imidazole was used. Further increase in the imidazole concentration up to 0.2% resulted in a marginal decrease in the peak exotherm temperature. Thermal stability of epoxy resin, cured isothermally, was evaluated by recording thermogravimetric traces in nitrogen atmosphere. The percent char yield was highest in case of resin sample, IP1-30 (i.e., DGEBA (1 mole) cured using 0.8 mole of PMDA in the presence of 0.3 (w/w) of imidazole).
2006
An investigation is conducted into the non-isothermal kinetics of the curing reaction of diglycidyl ether of bisphenol A (DGEBA) epoxy resin with two novel aromatic diamines, 4,4´-diaminostilbene (DAS) and 4,4´-diaminoazobenzene (DAAB), as curing agents. Kinetics analysis of the curing reaction of DGEBA with two different concentrations (29 wt% =0.13 mol% and 19 wt%=0.09 mol%) of the curing agents was studied using non-isothermal differential scanning calorimetry (DSC) technique. Two methods (Ozawa and Kissinger) for analysis of the scanning DSC data were applied to calculate the kinetic parameters and compared with kinetic parameters obtained from isothermal DSC tests using Kamal method. Activation energies in the range of 52.5-59.5 kJ/mol were obtained for both DGEBA/curing agent systems. The water absorption and resistance of the cured products against solutions of H 2 SO 4 and NaOH were also studied. Water uptake curves for both systems are similar. Weight loss for the cured pro...
Effect of structure on thermal behaviour of epoxy resins
European Polymer Journal, 2003
The paper deals with the curing behaviour of diglycidyl ether of bisphenol-A (DGEBA) using three novel multifunctional aromatic amines having phosphine oxide and amide-acid linkages. The amines were prepared by reacting tris(3-aminophenyl)phosphine oxide (TAP) with 1,2,4,5-benzenetetracarboxylic acid anhydride (P)/4,4 0-(hexafluoroisopropylidene)diphthalic acid anhydride (F)/3,3 0 ,4,4 0-benzophenonetetracarboxylic acid dianhydride (B). Amide-acid linkage in these amines is converted to thermally stable imide linkage during curing reaction. Curing temperatures of DGEBA were higher with phosphorylated amines than the conventional amine 4,4 0-diamino diphenyl sulphone (D). A decrease in initial decomposition temperature and higher char yields were observed when phosphorus containing amide-acid amines were used as curing agents for DGEBA.
Study of the Curing Process of DGEBA Epoxy Resin Through Structural Investigation
Macromolecular Chemistry and Physics, 2015
In this work, a multi-scale approach with different analytical methods is applied to study the curing process and the structural properties of a diglycidyl ether of bisphenol A (DGEBA) epoxy resin. This monomer, thermally cured using 4,4′-diaminodiphenilsulfone (DDS) as hardener, is analyzed after 10, 45, 90, and 120 min of reaction time at 180 °C to obtain information on samples with different cross-linking densities. Samples are also characterized after extraction in acetone in order to obtain structural information on the insoluble parts. For this purpose, differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), solid-state nuclear magnetic resonance (ss-NMR), and positron annihilation lifetime spectroscopy (PALS) are employed. The importance of this multi-method approach lies in the possibility to obtain a more complete knowledge of the investigated system, overcoming the limits inherent to the use of a single technique, through the correlation among results obtained from different structural investigation methodologies.