• Korean Journal of Materials Research
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• v.5 no.6
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• pp.667-672
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• 1995

Cure kinetics of DGEBA(diglycidyl ether of bisphenol A)/MDA(4, 4'-methylene dianiline)/SN(succinonitrile) system and DGEBA/MDA/SN/HQ(hydroquinone) system was studied by Kissinger equation and Fractional life method through DSC in the temperature range of 85∼150$^{\circ}C$. As cure temperature was increased, reaction rate increased and reaction order was almost constant. The reaction rate of the system with HQ as a catalyst was more higher and activation energy of that was lower about 20% than those of the system without HQ. Starting temperature of cure reaction for DGEBA/MDA/SN/HQ system decreased about 30$^{\circ}C$ than that of DGEBA/MDA/SN system.

• Journal of the Semiconductor & Display Technology
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• v.13 no.4
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• pp.27-32
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• 2014

The cure properties of self-extinguishing epoxy resin systems with different charge transfer type latent catalysts were investigated, which are composed of YX4000H as a biphenyl epoxy resin, MEH-7800SS as a hardener, and charge transfer type latent catalysts. We designed and used five kinds of charge transfer type latent catalyst and compared to epoxy resin systems with Triphenylphosphine-Benzoquinone(TPP-BQ) as reference system. The cure kinetics of these systems were analyzed by differential scanning calorimetry with an isothermal approach, the kinetic parameters of all systems were reported in generalized kinetic equations with diffusion effects. The epoxy resin systems with Triphenylphosphine-Quinhydrone(TPP-QH), Triphenylphosphine-Benzanthrone(TPP-BT) and Triphenylphosphine-Anthrone(TPP-AT) as a charge transfer type latent catalyst showed a cure conversion rate of equal or higher rate than those with TPP-BQ. These systems with TPP-QH and Triphenylphosphine-Tetracyanoethylene(TPP-TCE) showed a critical cure reaction conversion of equal or higher conversion than those with TPP-BQ. The increases of cure conversion rates could be explained by the decrease of the activation energy of these epoxy resin systems. It can be considered that the increases of critical cure reaction conversion would be dependent on the crystallinity of the biphenyl epoxy resin systems.

• Polymer(Korea)
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• v.25 no.2
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• pp.199-207
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• 2001

In the present study the cure behavior of diglycidyl ether of bisphenol-A(DGEBA) using an anhydride-based hardener in the presence of N,N-dimethyl benzyl amine (BDMA) or 1-cyanoethyl-2-ethyl-4-methyl imidazole (2E4MZ-CN) as an accelerator has been monitored and interpreted from the viewpoint of photophysical properties by means of fluorescence spectroscopy. To do this, 1,3-bis-(1-pyrene)propane (BPP) was well incorporated in the epoxy resin system by mechanical blending. The BPP probe, which is very sensitive to conformational change of the molecule influenced by the surrounding medium, successfully formed intramolecular excimer fluorescence. It is susceptible to the micro-viscosity or local viscosity and molecular mobility according to the epoxy cure. The cure behavior was explained with monomer fluorescence intensity ($I_{M}$ ), excimer fluorescence intensity ($I_{E}$ ) and $I_{M}$ /$I_{E}$ ratio as a function of cure time, cure temperature and accelerator. The present work agreed with the previous report on the cure behavior of an epoxy-anhydride system studied using DSC or torsion pendulum method. This study also suggests that the use of fluorescence technique may provide information on cure behavior of a thermosetting resin in a low temperature region, which has not been well interpreted by other analytical methods.

• Korean Journal of Materials Research
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• v.11 no.9
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• pp.727-732
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• 2001

The cure kinetics of diglycidyl ether of bisphenol A (DGEBA)/4,4'- methylene dianiline (MDA) system with synthesized phenyl glycidyl ether-dimethylurea (PGE-DMU) was studied by Kissinger and Ozawa equations with DSC analysis in the temperature range of $20~300^{\circ}C$ To investigate the reaction mechanism between epoxy group of PGE and urea group of DMU, FT-lR spectroscopy analysis was used. The epoxide group of PGE reacted with the urea group of DMU and formed a hydroxyl group which acted as a catalyst on the cure reaction of other epoxide and amine groups. The activation energy of DGEBA/MDA system without PGE-DMU was 46.5 kJ/mol and those of the system with 5 and 10 phr of PGE- DMU were 43.4 and 37.0 kJ/mol, respectively. Ozawa method also showed the same tendency.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.963-969
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• 1996

Cure characteristics of DGEBA(diglycidyl ether of bisphenol A)/dicy(dicyandiamide) system containing diuron(3-(3,4-dichloro phenyl) -1,1-dimethylurea) as an accelerator was investigated. The system has shelf life of six months because dicy is insoluble in liquid/solid resins at room temperature. It is generally known that dicy is an adequate curing agent for one component adhesive due to its highly latent property. With increasing the amount of added dicy, reaction heat of DGEBA/dicy system increased and degree of conversion was not varied. For DGEBA/dicy/diuron system, cure temperature decreased about $40^{\circ}C$ and cure reaction became fast by the addition of diuron which activates dicy. $T_g$ of the mixed resin decreased with the amount of accelerator. which was interpreated with molecular structure forming loose chain. Cure kinetics of DGEBA/dicy and DGEBA/dicy/diuron system were explained using Kamal's autocatalytic reaction model. The effect of acceleration was confirmed with that reaction model.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.34-37
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• 2000

The effect of novel N-crotyl-N,N-dimethyl-4-methylanilinium hexafluroantimonate (CMH) curing agent on cure behavior and thermal properties of DGEBA epoxy cationic system was investigated. From DSC measurements of DGEBA/CMH system, it was shown that this system exhibits an excellent thermal latent characteristic in a given temperature and reveals complex cure behavior as indicated by multiple exotherms. The conversion and conversion rate of DGEBA/CMH system increased with increasing the concentration of initiator due to high activity of CMH. Viscoelastic properties during gel formation of DGEBA with CMH were investigated by rheological techniques under isothermal condition. The gel time obtained from the modulus crossover. point t(G')=G", was affected by high curing temperature and concentration of CMH, resulting in high degree of network formation in cationic polymerization. The thermal stabilities were discussed in terms of the activation energy for decomposition and thermal factors determined from TGA measurements.ents.

• Polymer(Korea)
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• v.24 no.1
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• pp.105-112
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• 2000

Using a commercial epoxy/carbon fiber composite prepreg (DMS 2224) as a model system, the cure kinetics of vitrifying thermoset system were analyzed by isothermal and dynamic-heating experiments. Focusing on the processing condition of high performance composite systems, a phenomenological kinetic model was developed by using differential scanning calorimetry (DSC) and reaction kinetics theories. The model system exhibited a limited degree of cure as a function of isothermal temperature seemingly due to the diffusion-controlled reaction rates. The diffusion-controlled cure reaction was incorporated in the development of the kinetic model, and the model parameters were determined from isothermal experiments. The first order reaction was confirmed from the characteristic shape of isothermal cure thermograms, and the activation energy wes 78.43 kJ/mol. Finally, the proposed model was used to predict a complex autoclave thermal condition, which was composed of several isothermal and dynamic-heating stages.

• Polymer(Korea)
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• v.24 no.1
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• pp.65-71
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• 2000

The latent properties and cure kinetics of an acid anhydride-cured epoxy resin have been investigated by a near-infrared (NIR) reflection spectroscopy. The assignments of the latent properties and cure behaviors were performed by the measurements of the NIR reflectance for epoxide and hydroxyl groups at different temperatures. A comprehensive analysis of the origin, location, and shifts during reaction of all major NIR absorption peaks in the spectral range from 4000 to 7100 $cm^{-1}$ / was provided. The extent of reaction was determined from NIR absorption band at the 4530 $cm^{-1}$ / depending on epoxide concentration and cure temperature.

• Elastomers and Composites
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• v.46 no.2
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• pp.144-151
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• 2011

Intermittent CSR testing was used to investigate the degradation of a hydrogenated NBR(HNBR) O-rings, and also the prediction of its life-time. The cure system of HNBR O-ring was controlled as sulfur cure and peroxide cure system. An intermittent CSR jig was designed taking into consideration the O-ring's environment under use. The testing allowed observation of the effects of friction, heat loss, and stress relaxation by the Mullins effect. Degradation of O-rings by thermal aging was observed between 100 and $120^{\circ}C$. In the temperature range of $100-120^{\circ}C$, O-rings showed linear degradation behavior and satisfied the Arrhenius relationship. The activation energy of HNBR-S was about 70.6 kJ/mol. From Arrhenius plots, predicted life-times of HNBR-S O-ring were 31.1 years and 33.7 years for 50% and 40% failure conditions, respectively. In case of HNBR-P, the activation energy was about 72.1kJ/mol, and predicted life-times were 34.0 years and 36.5 years for 50% and 40% failure conditions, respectively. The peroxide cure system showed slower degradation rate and higher activation energy than the sulfur cure system.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.74-77
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• 2015

The cure kinetics of a neat epoxy system and epoxy/silica composite were investigated by DSC analysis. A cycloaliphatic type epoxy resin was diglycidyl 1,2-cyclohexanedicarboxylate and curing agent was anhydride type. To estimate kinetic parameters, the Kissinger equation was used. The activation energy of the neat epoxy system was 88.9 kJ/mol and pre-exponential factor was 2.64×10¹² min⁻¹, while the activation energy and pre-exponential factor for epoxy/silica composite were 97.4 kJ/mol and 9.21×10¹² min⁻¹, respectively. These values showed that the silica particles have effects on the cure kinetics of the neat epoxy matrix.