• Transactions of Materials Processing
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• v.31 no.5
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• pp.290-295
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• 2022

Recently, the use of high-tech ceramic parts in functional electronic parts, automobile parts and semiconductor equipment parts is increasing. These ceramics materials are required to have high reproducibility, reliability, large size and complex shapes. The researchers initiated the work to develop a new shaping method called gel casting, which allows high performance ceramic materials with a complex shape to be produced. The manufacturing process parameters of gel casting include uniform mixing of the initiator, bubble removal, and slip injection. In this study, we analyzed the dispersion and gelation characteristics according to the change in the additive content of the alumina slurry in the gel casting process. The alumina slurry for gel casting was prepared by mixing a solvent, a monomer and a dispersant through a ball mill. Alumina powder and a gelation initiator were added to the mixed solution, and ball milling was performed for 24 hours. A viscosity of 6,435 cps and a stable zeta potential value were obtained under the conditions of alumina powder content of 55 vol% and dispersant 2.0 wt%. After curing for 12 hours by adding aps 0.1wt%, TEMED 0.2wt%, and Monomer 3, 5wt%, it was possible to separate from the molding cup, confirming that the gelation was completed.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.556-560
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• 2009

Aggregation behavior of three kinds of benzindocarbocyanine dyes in aqueous methanol solution was studied by UV-Vis absorption spectrum. The results indicated that the three dyes all existed monomer-dimer equilibrium in aqueous methanol solution (concentration range $10^{−5}\;to\;10^{−6}$ M) at 25.0$\sim$41.0 ${^{\circ}C}$ for Dye 1, 28.0$\sim$49.0 ${^{\circ}C}$ for Dye 2 and 26.0$\sim$47.0 ${^{\circ}C}$ for Dye 3. The fundamental property of the three dyes as the dimeric association constant KD, the dimeric free energy ${\Delta$}G_D, the dimeric entropy ${\Delta$}S_D, and the dimeric enthalpy ${\Delta$}H_D were determined. The ${\Delta$}H_D of three dyes: Dye 1, Dye 2 and Dye 3 was -42.5, -15.1 and -18.9 kJ/mol, respectively. The experimental observations were the subject of a theoretical study including the ground-state geometries which were fully optimized using DFT at B3LYP/6-31G level. The effect of dye molecule structure on ${\Delta$}H_D was discussed by theoretical calculations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.76-85
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• 2019

Recently, various investigation of vegetable oil which is extracted from natural resources is being progressed because of its low cost and environmental aspect. However, double bonds in vegetable oil should be substituted to other high reactive functional group due to its low reactivity for synthesizing bio-polymeric materials. ${\alpha}$-eleostearic acid, which is consist of conjugated triene, is the main component of tung oil, and the conjugated triene allows tung oil to have higher reactivity than other vegetable oil. In this study, tung oil is copolymerized with styrene and divinylbenzene to make thermoset resin without any substitution of functional group. Thermal and mechanical properties are measured to investigate the effects of the composition of each monomer on the synthesized thermoset resin. The result shows that the products have only one Tg, which means the synthesized thermoset resins are homogeneous in molecular level. Mechanical properties show that tung oil act as soft segment in the copolymer and make more elastic product. On the other hand, divinylbenzene acts as hard segment and makes more brittle product.

• Journal of the Korean Applied Science and Technology
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• v.24 no.3
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• pp.287-295
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• 2007

Three phosphorus functional groups were introduced in one structural unit of polymer backbone to enhance the flame retardancy of PU coatings. In the first step, we synthesized tetramethylene bis(orthophosphate) (TBOP) that contained two phosphorus functional groups in one structural unit. In the next step, we synthesized modified polyesters (ATBTP-10C, -20C, -30C) that contained triphosphorus group using TBOP, 1,4-butanediol, trimethylolpropane, adipic acid, and another functional monomer, phenylphosphonic acid (PPA). The amount of PPA in ATBTPs was adjusted from 10 wt% to 30 wt%. The structure and characteristics of ATBTPs were examined using FT-IR, NMR, GPC, and TGA analysis. From the thermo-behavior test of diphosphorus modified polyester (ATBT) and ATBTPs, the afterglow of ATBT, ATBTP-10C, ATBTP-20C, and ATBTP-30C were 24.7, 27.1, 29.0, and 31.7%, respectively. It was found from this result that the afterglow increased with the amount of PPA component.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.209-213
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• 2006

Relationship between printability and rheological properties of UV flexographic (flexo) inks were investigated. UV flexo suspensions of carbon black in liquid medium having various binding materials such as acylate pre-polymer, di/multi-functional monomer, and diluents, were used as sample inks. Inks were characterized on a rheometer in terms of steady and dynamic behaviors. To understand the rheological properties of UV flexo inks, we must determine the specific rheological properties of chemical and/or physical interactions of their components (pigments, functional monomers, and pre-polymers). In particular, we discussed the influence of multi-functional monomers and the relationship between the rheological properties and transient networks formed by carbon black. In this study, we investigated the interrelationships between rheological properties of UV flexo inks and chemical and/or physical interactions of their components. To investigate correlations between the printability and the rheological behaviors induced by interfacial interactions between ink compositions, we carried out rheological tests of UV ink suspensions. The results were compared with printing tests so as to find out the relationship between printability and rheological properties of ink.

• Journal of Adhesion and Interface
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• v.2 no.3
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• pp.25-32
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• 2001

Ethyl cyanoacrylate (ECA) is used as an instant adhesive, and it can be readily polymerized by moisture in air without any initiator and applied for industrial products and ohome use. However, pure ECA monomer is low-viscosity liquid at room temperature that flows into substrate surface. To thicken the instant adhesive, poly(methyl methacylate)(PMMA) is often added in it commercially. Another disadvantage of instant adhesive polymer is its brittleness In this study, functional polymers including PMMA for an additive of ECA were prepared to increase viscosity of the monomer and flexibility of the adhesive atthe same time The additives, P(MMA-VAc-EVE), were synthesized by radical copolymerization of MMA with VAc and EVE having low glass transition temperature (Tg). The additives were added to ECA to get functional instant adhesives. The chemical structures of the additives and ECA polymers were confirmed by $^1H$ NMR and FTIR, and their physical and mechanical properites were also evaluated. The Tg of the obtained additives decreased with increasing the content of VAc or VAc-EVE, indicating more improved flexibility. In addition, functional instant adhesive containing the additives showed higher bonding strength than that of the existing one.

• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.805-810
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• 2007

Molecular recognition for a specific cation depending on the change of the oxidation state of the metal catalyst component contained in the hydrogel network has been studied in a self-oscillating hydrogel. The selfoscillating hydrogels are synthesized by the copolymerization of N-isopropylacrylamide (NIPAAm), lead methacrylic acid (Pb(MAA)2), and Ru(bpy)3 2+ monomer as a metal catalyst component. The recognition for a specific cation (in this study, Ca2+ has been used) is characterized by the adsorbed amount of Ca2+ into the gel. The recognition of the gels for Ca2+ is higher at the temperature below the LCST, and also higher at the oxidized state than at reduced state of the metal catalyst component which corresponds to a more swollen state. Moreover, a propagating wave induced by a periodic change of the oxidation state with the diffusion phenomena in the oscillating hydrogel shows a possibility for temporal and site-specific molecular recognition due to the local swelling of the gel.

• Journal of Adhesion and Interface
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• v.10 no.1
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• pp.1-10
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• 2009

The waterborne acrylic pressure-sensitive adhesive in the basis of butylacylate (BA) and 2-Ethylhexylacrylate (2-EHA) was synthesized and the methyl methacrylate (MMA) have been used to give the rigidity perfroamce. The polymreric latex was synthesized using butyl acrylate (BA), 2-ethylhexyl acrylate (EHA), methyl methacrylate (MMA) and each 1, 2, 3% of various functional monomers. The dimethyl-2-imidazlidon acrylate and 2-acrylamido-2-methyl-1-propanesulfonate was used in order to increase the wetting properties of acrylic emulsion. To study of properties of functional monomer, The polymreric latex was synthesized various functional monomers each 1, 2, 3%. The 2-acrylamido-2-methyl-1-propanesulfonate showed the best properties. Latex with acrylic acid and dimethyl-2-imidazlidon acrylate had good peel strength, holding power, but it showed that they didn't separate from adhered cleanly by weak cohesion strength. The adhesion performance was increased by increasing amount of 2-acrylamido-2-methyl-1-propanesulfonate however latexes with upper 7% 2-acrylamido-2-methyl-1-propanesulfonate showed that the properties of PSA decreased.

• Journal of Sensor Science and Technology
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• v.21 no.5
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• pp.345-351
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• 2012

Biomimetic terpene sensors which have high sensitivity and stability have been fabricated using moleculary imprinted polymer (MIP) technology. Since it is impossible to make a resistive type sensor due to the high resistance of MIP, we improved the sensor by adding conductive polymers. We investigated the sensitivity of resistive type sensors with nano particles depending on the amount of conductive polymers. The MIP membrane contained the methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross linker, which formed specific cavities originated by the target terpene molecules. The mixture of MIP and the conductive polymer was coated on the patterns of interdigit electrodes on the alumina substrate. The fabricated sensors showed their highest specific sensitivities exposed to 500 ppm target gases : limonene 0.055 at 40% of amount of conductive polymers and geraniol $5.84{\times}10^{-4}$ at 20% of amount of conductive polymers. In conclusion, we found that the terpene sensors are affected by the target molecules, functional monomers and the conductive polymers.

• Textile Coloration and Finishing
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• v.22 no.4
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• pp.293-299
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• 2010

A methacrylate monomer having phospholipid polar group and cell membrane structure is known as highly biocompatible. Based on these properties, new biocompatible multi-functional textile finishing agent was developed using phospolipid copolymer. 2-Methacryloyloxyethyl phosphorylcholine (MPCE) was synthesized using 2-hydroxyethyl methacrylate (HEMA), 2-chloro-2-oxo-1,3,2-dioxaphospholane (COP) and triethylamine (TEA), and then polymerized to prepare MPCE copolymer by radical polymerization using azobisisobutyronitrile(AIBN). The structures of MPCE was characterized by FT-IR and 1H NMR and will be evaluated as textile finishing agent in further study.