• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.973-978
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• 1997

The toughness and morphology of epoxy resin based on diglycidyl ether of bisphenol A(DGEBA) cured with of tris (dimethylaminomethy]) phenol(DMP-30) and castor oil (CO) as a toughening modifier have been studied. Mixtures of CO and an epoxy resin showed a higher miscibility than the classical CTBN modified epoxy resin. The glass transition temperature($T_g$) was decreased with the CO content and the cure temperature. It is interpreted that the networks of epoxy matrix obtained at high temperature are apparently looser and more flexible due to the lower crosslinking density. The toughness was slightly increased with the CO content at $40^{\circ}C$ of curing temperature. The toughness increased with increasing the cure temperature and CO content.

• Macromolecular Research
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• v.10 no.3
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• pp.135-139
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• 2002

Blends of the linear bisphenol-A polycarbonate (L-PC) and randomly branched bisphenol-A polycarbonate (Br-PC), prepared by co-rotating twin screw extrusion, were investigated using differential scanning calorimetry (DSC), sag resistance time tester, extensional rheometry, and advanced rheometric expansion system (ARES). From the DSC results, the glass transition temperature (T$_{g}$) of the L-PC/Br-PC blend was increased with the increase of Br-PC in the blend, and the blend showed a single T$_{g}$, which suggests a miscible blend. The sag resistance time of the L-PC/Br-PC blend was increased with the increase of Br-PC in the blends. From the results of rheological measurements of the L-PC/Br-PC blends, the extensional viscosity and the complex viscosity of the blends were found to increase with the increase of Br-PC in the blends. The increase of extensional viscosity and complex viscosity was related with the increase of sag resistance time with the Br-PC in the L-PC/Br-PC blends.nds.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.55-59
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• 2009

The epoxy resin without hardener can harden by a ring-opening reaction in the presence of the alkalies produced by the hydration of cement in epoxy-modified mortars and concretes. This paper investigates the effect of curing conditions on the strength improvement of polymer-modified mortars using bisphenol A-type epoxy resin without hardener. The polymer-modified mortars using epoxy resin are prepared with various polymer-cement ratios, and subjected to ideal, water, dry and heat cures. In the heat cure, the epoxy-modified mortars are sealed or unsealed with a PVDC (polyvinylidene chloride) film. The epoxy-modified mortars are tested for flexural and compressive strengths at desired curing methods. The microstructures of the epoxy-modified mortars are also observed by scanning electron microscope. The effects of curing conditions on the strength development of the epoxy-modified mortars are examined. From the test results, the marked effectiveness of the heat cure under the PVDC film sealing against the development of the strength of the epoxy-modified mortar without the hardener is recognized. The flexural and compressive strengths of 7-day-90℃ heat-cured, PVDC film-sealed epoxy-modified mortars without hardener reach 7 to 17MPa and 24 to 44MPa respectively, and are two to three times of Unmodified mortar. Such high strength development of the epoxy-modified mortars may be achieved by the dense microstructure formation by cement hydrates and the hardening of the epoxy resin in the mortars.

• Korean Journal of Materials Research
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• v.3 no.2
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• pp.140-144
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• 1993

Abstract To modify brittleness among the properties of thermosetting epoxy resin, a reactive additive. succinonitrile(SN) was introduced to Diglycidyl ether of bisphenol A(DGEBA)-4, 4'-methylene dianiline (MDA) system. Fracture behavior was microscopically studied during breaking of composite materials. As a result, post debond friction energy was the most significant for breaking the composite having glass fibres, pull-out energy was the next significant and debonding energy was the last. It was observed that shear stress between glass fibre and epoxy matrix was main factor for fracture behavior. Reactive additive, SN made shear stress deteriorated.

• Applied Chemistry for Engineering
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• v.17 no.2
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• pp.144-149
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• 2006

Non-halogen flame retardants have been the focus of extensive research because of environmental problems. Hexakisp-henoxycyclotriphosphazene was synthesized in order to use as the flame retardant of ABS resin. And using bisphenol A, the polymers containing a cyclotriphosphazene structure were synthesized in order to also use as the flame retardant of ABS resin. All of the synthesized polymers themselves had the excellent flame retardancy. And as their molecular weight and crosslinking density were increased, the thermal stability was increased. But when the synthesized compounds were used as the flame retardant for ABS resin, the lower molecular weight compound in these compounds showed the better flame retardancy and the better physical properties of ABS resin.

• Polymer(Korea)
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• v.25 no.2
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• pp.208-217
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• 2001

PET/BPA copolymer of terephthalic acid, bisphenol-A and ethylene glycol was melt-pressed and quenched in ice water. This copolymer film was drawn by capillary rheometer. Shrinkage, crystallinity, morphology, thermal, dynamic mechanical, and mechanical properties of these copolymer films were investigated. The PET/BPA copolymer film exhibited T$_{m}$ lower than that of PET film. The crystallinity and density of these drawn copolymer films increased with draw ratio and draw rate but decreased with draw temperature. The tensile strength and tensile modulus of the copolymer films increased with draw ratio but decreased with draw temperature. Shrinkage of the drawn copolymer film decreased with draw ratio and draw rate.e.

• Polymer(Korea)
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• v.37 no.1
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• pp.41-46
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• 2013

The glass transition temperature ($T_g$) and conversion (${\alpha}$) were measured for a diglycidyl ether of bisphenol A (DGEBA) epoxy/aromatic amine system incorporated with an organic-inorganic hybrid molecule, polyhedral oligomeric silsesquioxane (POSS). Samples isothermally cured at varying cure temperatures and times were analyzed by differential scanning calorimetry (DSC). $T_g$ vs. ln (time) data at an arbitrary reference were superposed by time-temperature shifts for the kinetically controlled reaction, and the shift factors were used to calculate an Arrhenius activation energy. Influence of POSS was investigated from $T_g$ vs. ${\alpha}$ data, which in turn were fitted with DiBenedetto equation.

• 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.

• Macromolecular Research
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• v.10 no.6
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• pp.332-338
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• 2002

The effect of an electron beam and ${\gamma}$-ray irradiation on the curing of epoxy resins was investigated. Diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) as epoxy resin were used. The epoxy resins containing 1.0-3.() wt% of triarylsulphonium hexafluoroantimonate(TASHFA) and triarylsulphonium hexafluorophosphate(TASHFP) as initiator were irradiated under nitrogen at room temperature with different dosage of EB and ${\gamma}$-rays from a Co$^{60}$ u source. The chemical and mechanical characteristics of irradiated epoxy resins were compared after curing of EB and ${\gamma}$-ray irradiation. The thermal properties of cured epoxy were investigated using dynamic mechanical thermal analysis. The chemical structures of cured epoxy were characterized using near infrared spectroscopy. Mechanical properties such as flexural strength, modulus were measured. The gel fraction of DGEBA with ${\gamma}$-ray was higher than that of the epoxy with EB at the same dose. Young's modulus of the sample irradiated by ${\gamma}$-ray is higher than that of sample cured by EB. From the result of strain at yield, it was found that the epoxy cured by ${\gamma}$-ray had a higher stiff property compared with the irradiated by EB.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.11b
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• pp.162-162
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• 2002

There has been many findings of natural, environmental or manufactered nonsteroidal substances shown to have estrogenic activity. Since estrogens affect reproduction and cellular development to cause disease in people or animals, chronic exposure may have a major impact on health.(omitted)