• Journal of the Korean Wood Science and Technology
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• v.32 no.6
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• pp.23-35
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• 2004

The goal of study was to investigate the influence of the acrylated urethane oligomer on mechanical properties, the chemical resistance and thermal resistance of the UV curable urethane acrylate coatings for fancy veneer overlayed plywood flooring. The pencil hardness and abrasion resistance of the coated fancy veneer overlayed plywood floorings increased with increasing the acrylate functionality of the acrylated urethane oligomer. In the case of the UV cured film containing hexa-functional acrylated aliphatic urethane oligomer, high discoloration of the coated fancy veneer overlayed plywood flooring was observed near the cracks at the beginning of the chemical treatment. In this study, it was found that the degradation of the UV cured film caused by an alkaline reagent was higher than that of the UV cured film caused by an acidic treatment.

• Elastomers and Composites
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• v.27 no.1
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• pp.20-26
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• 1992

Reactions between chlorinated or brominated poly(isobutylene-isoprene) (CIIR and BIIR, respectively) and 3-mercaptopropyltrimethoxysilane(MPS) were kinetically studied by gas chromatography in solution state. CIIR and BIIR were mixed with MPS and dibutyltin dilaurate as catalyst on roll mill and then the compounds were cured in hot water or atmosphere. From the gas chromatography, reaction order, activation energy, and frequency factor were determined. Crosslinking density and physical properties of moisture-cured CIIR and BIIR were measured. CIIR and BIIR were effectively moisture-cured and physical properties of these rubbers were comparatively good.

• Composites Research
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• v.32 no.6
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• pp.349-354
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• 2019

The Aluminum conductor composite core consists of fast-curing thermosetting epoxy used as reinforcements and carbon fiber and glass fiber used as matrix. In this study, we have investigated fast curing epoxy cured products used for composite core(Aluminum Conductor Composite Core, ACCC). Tetrafunctional epoxy(PA 806) was used as a multifunctional epoxy, along with two kinds of curing agents, MNAn(5-Methyl-5-norbornene-2,3-dicarboxylic anhydride) and HHPA(Hexahydrophthalic Anhydride), to make an epoxy cured product and their properties were evaluated. Optimum conditions are confirmed by varying the content of curing accelerator in the selected epoxy and curing agent.

• Elastomers and Composites
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• v.55 no.2
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• pp.95-102
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• 2020

Currently, peroxide cure is a widely used cure system for rubber materials. To improve its effectivity, co-agents are used to enhance the peroxide efficiency and mechanical properties of rubber materials. Co-agents are multifunctional organic compounds that are highly reactive towards free radicals. These co-agents provide higher cross-link densities for a given peroxide concentration and improve the mechanical properties of peroxide-cured rubber composites. In this study, trimethylolpropane trimethacrylate (TMPTMA) and high vinyl 1,2-polybutadiene (HVPBD) were used as co-agents. In order to obtain a concentration that achieves a favorable balance between mechanical properties and co-agent concentration, this research investigated the effects of co-agent content on the curing characteristics, chemical structures, and mechanical properties of HNBR composites. Additionally, the heat aging properties and compression sets of HNBR composites were investigated. Based on the results, we found that the HNBR composites with TMPTMA co-agents exhibited higher Shore A hardness and 10% modulus and better heat aging resistance and compression set than that of the HVPBD co-agent. The heat aging resistance and compression set deteriorated with increasing HVPBD content.

• Elastomers and Composites
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• v.32 no.1
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• pp.11-19
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• 1997

[ ${\gamm}-Glycidoxy$ ] propyl trimethoxy silane, CTBN rubber(carboxyl terminated butadiene acrylonitrile rubber) and GMA(glycidyl methacrylate) were reacted on the surface of silica one by one in existence of TEA(triethylamine) or BPO(benzoyl peroxide). The amount of reactant was $2.5{\sim}5.8%$ of treated silica weight. The treated silica was mixed with epoxy resin and MTHPA(methyl tetrahydro phthalic anhydride) in the range of $0{\sim}60%$(wt.%) of total component. The thermal properties were tested for cured products. By using silica treated with silane/rubber or silane/rubber/vinyl, comparing with 3% of rubber mixed directly, it had 13% higher $T_g$ and 10% lower thermal expansion coefficient at $35{\sim}55%$ of silica contents.

• Elastomers and Composites
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• v.26 no.2
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• pp.115-122
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• 1991

Polychloroprene rubber was moisture-cured after treating them with silane coupling agents such as 3-mercaptopropyltrimethoxysilane(MPS), 3-methacryloxypropyltrimethoxysilane(MAS) and vinyltriethoxysilane(VES), especially MPS. The cure reaction is composed of two steps. The first is the reaction between chlorine atoms of CR and silane coupling agents. The second is the formation of cross-links which are siloxane linkage. The linkage is formed by the condensation of silanol groups which are produced by the hydrolysis of alkoxysilyl groups. The first reaction was kinetically studied and the reactivity of CR to silane coupling agents was determined in previous literature. Crosslinking density and mechanical properties of the moisture-cured elastomer filled with silica or non-filled were studied and the feasibility of this cure system was discussed.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.169-179
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• 2007

This study was to compare the microshear bond strength $({\mu}SBS)$ of light- and chemically cured composites to enamel coupled with four 2-step self-etch adhesives and also to evaluate the incompatibility between 2-step self-etch adhesives and chemically cured composite resin. Crown segments of extracted human molars were cut mesiodistally, and a 1 mm thickness of specimen was made. They were assigned to four groups by adhesives used: SE group (Clearfil SE Bond) AdheSE group (AdheSE), Tyrian group (Tyrian SPE/One-Step Plus), and Contax group (Contax) Each adhesive was applied to a cut enamel surface as per the manufacturer's instruction. Light-cured (Filtek Z250) or chemically cured composite (Luxacore Smartmix Dual) was bonded to the enamel of each specimen using a Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to ${\mu}SBS$ testing with a crosshead speed of 1 mm/minute. The mean ${\mu}SBS$ (n=20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at 95% level. Also the interface of enamel and composite was evaluated under FE-SEM. The results of this study were as follows ; 1. The ${\mu}SBS$ of the SE Bond group to the enamel was significantly higher than that of the AdheSE group, the Tyrian group, and the Contax group in both the light-cured and the chemically cured composite resin (p < 0.05). 2. There was not a significant difference among the hdheSE group, the Tyrian group, and the Contax group in both the light-cured and the chemically cured composite resin. 3. The ${\mu}SBS$ of the light-cured composite resin was significantly higher than that of the chemically cured composite resin when same adhesive was applied to the enamel (p < 0.05). 4. The interface of enamel and all 2-step self-etch adhesives showed close adaptation, and so the incompatibility of the chemically cured composite resin did not show.

• Journal of Adhesion and Interface
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• v.12 no.4
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• pp.105-110
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• 2011

Polyester/melamine cured coatings had been used for pre-primed coatings and pre-coated metal coatings, because it has good mechanical,chemical properties, and mar resistance. But it has weak points such as stiffness and low formability for making automotive components. Polyester had been synthesized using polycarbonate diol of long alkyl chain which can improve flexibility and formability which is one of the important factors for pre-coated steel sheets (PCM). In this study, strain and tensile strength were examined by the tensile test and formability was examined by the drawing test. Also, Those polyester resins were also measured by DMA to verify flexibility of cured coatings.

• Journal of the Korean Wood Science and Technology
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• v.41 no.2
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• pp.134-140
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• 2013

UV curing was introduced via a chemical treatment by adding small amounts of a hexafunctional acrylic monomer and a photoinitiator to improve the mechanical properties of PLA. This study also employed a semi-interpenetrated structured polymer network through the process of UV-curing. The UV curing behaviors were investigated using FTIR-ATR spectroscopy and gel fraction determination. Also, the tensile strength was investigated with different hexafunctional acrylic monomer contents and UV doses. The results showed that the crosslinking of UV-induced chemically treated PLA started at a low content of hexafunctional acrylic monomer, resulting in a significant improvement of the mechanical properties compared to those of neat PLA due to crosslinking.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.124-132
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• 1990

In order to improve the mechanical properties and fracture toughness of HPT 1071/DDS system, poly(aryl etherimide) (PEI) was incorporated in the resin system. In HPT 1071/DDS system, mechanical properties of cured epoxy resins were not strongly dependent on the concentration of DDS curing agent strongly. In the case of HPT 1071/DDS/PEI system, the fracture toughness and flexural properties of epoxy resins increased with increasing the concentration of PEI. SEM micrographs of cured epoxy resin indicated that the phase separation occured at the low concentration of PEI in this system. In addition, investigation of the relationship between mechanical properties and the morphology of modified epoxy resin was undertaken in HPT 1071/DDS/PEI system.