• Journal of Adhesion and Interface
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• v.4 no.3
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• pp.33-40
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• 2003

In this work, diglycidyl ether of bisphenol A (DGEBA)/polyetherimide (PEI) blends were cured using 4,4-diaminodiphenyl methane (DDM). And the effects of addition of different PEI contents to neat DGEBA were investigated in the thermal properties and fracture toughness of the blends. The contents of contents of containing PEI were varied in 0, 2.5, 5, 7.5, and 10 phr. The cure activation energies ($E_a$) of the cured specimens were determined by Kissinger equation and the mechanical interfacial properties of the specimens were performed by critical stress intensity factor ($K_{IC}$). Also their surfaces were examined by using a scanning electron microscope (SEM) and the surface energetics of blends was determined by contact angles. As a result, $E_a$ and $K_{IC}$ showed maximum values in the 7.5 phr PEI. This result was interpreted in the increment of the network structure of DGEBA/PEI blends. Also, the surface energetics of the DGEBA/PEI blends showed a similar behavior with the results of $K_{IC}$. This was probably due to the improving of specific or polor component of the surface free energy of DGEBA/PEI blends, resulting in increasing the hydrogen bonding of the hydroxyl and imide groups of the blends.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2643-2646
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• 2009

In this study, a novel phosphorus-containing flame retardant copolymer of spirocyclic pentaerythritol di(phosphate monochloride) and bisphenol S (SPD-BS) was successfully synthesized and used as a flame retardant in diglycidyl ether of bisphenol A (DGEBA) epoxy resins. The chemical structure of the SPD-BS was characterized using FT-IR and $^1H$ NMR spectra. The thermal properties were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The effects of SPD-BS and nano-$CaCO_3$ on the flame-retardant properties of DGEBA/SPD-BS systems were evaluated by measurement of the burning rate. As a result, the thermal stabilities of the DGEBA/SPD-BS systems were decreased with increasing SPD-BS content. The flame-retardant properties and char yields of the systems were significantly increased when SPD-BS content increased. The synergism of nano-$CaCO_3$ incorporation on flame retardancy was found for the DGEBA/SPD-BS systems.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.373-377
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• 1999

The cure mechanicsm and cure kinetics of diglycidyl ether of bisphenol A(DGEBA)/4,4'-methylene dianiline(MDA)/nitrile(MN, SN, GN) systems were studied by FT-IR and DSC to develop new applications in the biomedical polymer fields. The network structure of the DGEBA/MDA system was changed to the chain-extended network structure by the addition of nitriles. The reactions contributed to the chain extension were the primary amine-nitrile and hydroxyl-nitrile reactions. The chain-extended network structure could be indirectly proved by the decrement of T\ulcorner and the increment of impact strength with the increasing nitrile content. The cure rate of DGEBA/MDA/nitrile system was lower than that of DGEBA/MDA system due to the disturbance of nitrile group in the reaction of primary amine and epoxide groups.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.389-392
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• 1997

Glutaronitrile(GN) was introduced to diglycidyl ether of bisphenol A(DGEBA)/ 4,4'-methylene dianiline(MDA) system to improve toughness. Effects of GN contents on thermal decomposition of epoxy resin system were investigated. To study the characteristics of thermal decomposition, thermo-gravimetric analysis(TGA) and Kissinger equation were used. Thermal degradation temperatures were about 365$^{\circ}C$ regardless of GN contents. Activation energies of thermal decomposition in epoxy resin system were almost constant below 10 phr and decreased above 15 phr.

• 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.

• Macromolecular Research
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• v.16 no.6
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• pp.532-538
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• 2008

Epoxy-based azopolymers were synthesized by the reaction of the diglycidyl ether of bisphenol A (DGEBA) or N,N-diglycidyl aniline (DGA) with disperse orange 3 (DO3) to give poly(DGEBA-co-DO3) or poly(DGA-co-DO3), respectively. Aniline-based azopolymers prepared from poly(DGA-co-An) precursors, synthesized by the reaction of DGA with aniline, were produced by the post-azo coupling reaction with diazonium salts containing various substituents. Holographic gratings were carried out to measure the diffractive efficiencies (DE) for the interference patterns of the $Ar^+$ laser from 50 to $300\;mW/cm^2$ intensity. The shorter repeating unit with higher chromophore density induced deeper surface relief gratings (SRG). Large surface gratings were observed for the aniline-based azopolymers with -COOH substituents, as compared with those for epoxy-based azopolymers. The aniline-based azopolymers with dimerized chromophores and various substituents were also synthesized to observe the effect of chromophore substituents and dimerization on the holography. The dimerized chromophores were more sensitively photoisomerized by the $Ar^+$ laser beam, and demonstrated a larger grating than that with one azo bond.

• Textile Coloration and Finishing
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• v.30 no.3
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• pp.180-189
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• 2018

To study the effect of stereoisomeric structures of curing agents on curing behaviors, thermal and mechanical properties of epoxy resins, DGEBA(diglycidyl ether of bisphenol A) epoxy resin and 3,3'- and 4,4'-DDS(diaminodiphenyl sulfone) curing agents were selected. The curing initiation temperature and activation energy of DGEBA/3,3'-DDS was lower than DGEBA/4,4'-DDS. DGEBA/3,3'-DDS has a faster curing rate and higher degree of cure than DGEBA/4,4'-DDS, suggesting that 3,3'-DDS has higher reactivity than 4,4'-DDS. Tensile strength and fracture toughness of DGEBA/3,3'-DDS was lower than those of DGEBA/4,4'-DDS, indicating that mechanical properties of the epoxy resin can be different only by the stereoisomeric difference in chemical structure of the curing agent.

• Textile Coloration and Finishing
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• v.31 no.2
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• pp.118-126
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• 2019

This study aims to investigate the effect of polytriazolesulfone(PTS) addition on fracture toughness of diglycidyl ether of bisphenol A(DGEBA) and 4,4'-diaminodiphenylsulfone(DDS). Various amounts of PTS were added to DGEBA/4,4'-DDS in diazide and dialkyne monomer forms and polymerized during the epoxy curing process. Fracture toughness(K1C), tensile properties and thermal stability of the PTS added epoxy resin were evaluated and compared with those of PES, the conventional high Tg toughening agent, added epoxy resin. Fracture toughness of the PTS added epoxy resin was dramatically improved up to 133%, as the amount of PTS added increased, whereas that of the PES added epoxy resin was improved by only 67%. The tensile strength of PTS added DGEBA/4,4'-DDS was similar to the epoxy resin without PTS and tensile modulus was improved by 20%. And thermal stability of the PTS added epoxy resin was improved up to 14%. Therefore, PTS addition to DGEBA/4,4'-DDS, as a toughening agent, is very effective way to improve its fracture toughness without any lowering in other properties.

• Polymer(Korea)
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• v.24 no.4
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• pp.571-577
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• 2000

A new type of filler for epoxy-clay nanocomposites has been prepared by the reaction of octadecyltrimethylammonium bromide and layered sodium montmorillonite (MMT) via an ion-exchange reaction. The gallery space was further modified by grafting the aminopropyl groups via a reaction between a octadecyltrimethylammonium-MMT and 3-aminopropyltriethoxysilane (APS). The interlayer modification of MMT was confirmed by XRD, IR, and solid-state $^{29}$ Si CP/MAS NMR. Furthermore, clay-polymer nanocomposites have been synthesized by the polymerization of diglycidyl ether of bisphenol A(DGEBA) and $C_{18}$ H$_{37}$ N($CH_3$)$_3$-APS-MMT. The resulting hybrid nanocomposites were characterized by XRD, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results proved that the organomontmorillonite could be exfoliated and uniformly dispersed in the epoxy matrix.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.73-76
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• 1999

Near infrared spectroscopy techniques were used to study the cure reactions of epoxy resin system based on diglycidyl ether of bisphenol A(DGEBA) resins cured with 4, 4' diaminodiphenyl sulfone (DDS) hardner. Stoichiometric DGEBA/DDS resin formulation was involved in this study. The infrared absorption spectra of the prepared formulation were obtained on an FTIR spectrometer operating in the region of 11000 to 4000$cm^{-l}$. The chemical group peaks of interest in a DFEBA/DDS spectrum were identified by a comparative study with individual spectra of DGEBA and DDS monomers. Where necessary, special model compounds were used to identify unknown bands, such as the primary amine band at 4535$cm^{-l}$. The absorption bands of interest were integrated to quantify the areas and then converted to molar concentrations. This series of quantitative analyses of the major chemical groups led us to understand not only the reaction mechanism but also the cure kinetics. In this paper, the reaction mechanisms observed in stoichiometric DGEBA/DDS resin formulation and the various properties of the resin system as a function of cure temperature are described.