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Characteristics of phenolic adhesives reinforced with graphenes
백건욱,공민선,강연호,한윤수 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Phenolic resins are oligomers synthesized by repeatedly linking phenolic monomers with formaldehydes. The primary use of phenolic resin is as a bonding agent. Phenolic resin easily penetrates and adheres to the surface of various substrates or organic/inorganic fillers and reinforcements, which makes it an ideal candidate for various end uses. In this study, adhesion strength of phenolic adhesives was evaluated with contents of crosslinker, temperature of heat treatment and processing pressure. Effects of graphene as a filler on the adhesion strength were also investigated.
백건욱,김영진,정경혜,한윤수 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.73 No.-
Polyacrylonitrile (PAN) was adsorbed onto the TiO2 surface, and the resulting photoelectrodes wereapplied in dye-sensitized solar cells (DSSCs). The DSSC with the PAN-modified TiO2 showed an increase inits short-circuit current (Jsc) and a decrease in its open-circuit voltage (Voc), resulting in a 17%enhancement of its photovoltaic performance when compared to the reference cell. By incorporating PANonto the surface of the TiO2, a surface dipole was formed, which induced a conduction band edge shift ofthe TiO2 in a positive direction. This shift led to a considerable improvement in the electron injectionefficiency, and hence the Jsc.
Physical properties of UV-cured films prepared from mixed oligomers of urethane and epoxy acrylate
백건욱,신동원,김욱현,강천수,한윤수 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
UV-curable resins consisting of an urethane acrylate oligomer, an epoxy acrylate oligomer, an acrylate monomer, an acrylate cross-linker, and a photoinitiator were prepared, and they were cured by UV light of 365 nm to prepare crosslinked films. Physical properties of the films such as hardness, swelling ratio in various solvent, cross-linking density, and average molecular weight between cross-linking points were investigated. Thermal properties of them were also measured.
Swelling ratio and crosslinking density of UV-cured films prepared from urethane acrylate oligomer
백건욱,신동원,이상주,강천수,한윤수 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
UV-curable resins with good film-forming capability were prepared, and their thermal and physical properties were investigated. The relative photosensitivity determined by the gray scale method showed that DTMPTA was the most suitable cross-linker for the photo-curable resins. The swelling ratios of the UV-cured films in methylene chloride, chloroform and dimethyl acetate were higher than those of other organic solvents. By increasing the cross-linker content in the UV-curable resins, the cross-linking density of UV-cured films was increased, and the swelling ratio and average molecular weight between the crosslinking points were decreased.
Effects of additives on the adhesion strength of phenolic adhesives based on a novolac resin
백건욱,신중현,이동원,한윤수 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Phenol formaldehyde resins or phenolic resins are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde, and there are two types of phenolic resins, i.e, novolac and resol. They have been widely used as coatings and adhesives. Phenolic resin easily penetrates and adheres to the surface of various substrates or organic/inorganic fillers and reinforcements, which makes it an ideal candidate for various end uses. In this study, phenolic adhesives based on the novolac were prepared, and crosslinking conditions such as contents of crosslinker, temperature of heat treatment and processing pressure were optimized. Effects of additives on the adhesion strength of novolac-based adhesives was also evaluated. In addition, to improve the adhesion strength, primers were introduced between the adhesives and an adherend.
Preparation and characteristics of polymer composites with methacrylated graphenes
백건욱,류형석,이상미,강연호,한윤수 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
To secure efficient interactions between polymer matrices and graphenes, as-received graphenes were functionalized to create surface methacrylate groups, which could be crosslinked with matrix polymers in the existence of radical generators. Graphens were reacted with a silane coupling agent in a solution of ethanol, water and acetic acid to functionalize the surface of them. Radiation curable resins composed of oligomers, a monomer, a photoinitiator and a crosslinker were prepared, and then cured by exposure to 365-nm irradiation. Thermal and mechanical properties of the cured films were evaluated, and the swelling ratio, cross-linking density and average molecular weight between cross-linking points in the films were also quantified. In addition, the radiation-cured films reinforced with the methacrylated graphenes or as-received non-functionalized graphens were also prepared, and their physical properties were compared.
백건욱 ( Baek Geon Wook ),한윤수 ( Han Yoon Soo ) 대구가톨릭대학교 자연과학연구소 2019 자연과학연구논문집 Vol.17 No.1
For successful fabrication of graphene-reinforced adhesives, the specific surface modification of graphene was key issues to provide better dispersion of graphene and to obtain a higher adhesion by chemical bonding between the polymer matrix and the graphene particles. The surface hydroxyl groups of the as-received graphenes were modified via hydrolysis of N- (3-trimethoxysilyl propyl) - 4 - hydroxy butylamide as a surface modifier to create reactive methylol groups on the surface of graphene. Resol-type adhesives reinforced with methylolated graphenes were prepared and evaluated. As a result, the methylolated graphene was found to be effective in providing a higher adhesion strength and thermal stability of the adhesives, due to chemical grafting to resol resin.