• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.283-290
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• 2002

Generally polymer mortar and concrete using unsaturated polyester resin has high strengths and good chemical resistance. However it also has high brittleness and because of this reason, it is not used for the purpose that demands high resistance to impact. The purpose of this study is to improve the brittleness of unsaturated polyester mortar(UPE mortar) which could be used for the flooring material with recycled aggregates and UPE. Polyurethane liquid rubber(PU) and recycled aggregates were used to complement the brittleness and to recycle the resources respectively. The characteristics of mortar were investigated according to the molecular weight and substitution rate of PU. As the molecular weight and PU substitution rate were increased, the viscosity was increased, working life became fast and curing shrinkage was reduced. Compressive and flexural strengths were also reduced but tile brittleness was improved. Therefore, it is seemed that the improved WE mortar could be obtained by using polyurethane liquid rubber with the polyol of molecular weight 2000, 3000.

• Composites Research
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• v.36 no.1
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• pp.37-41
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• 2023

The treated water inside the ballast electrolytic cell creates a highly alkaline atmosphere due to hydroxide generated at the DSA(Dimension Stable Anode) electrode during electrolysis. In this study, a composite material that can replace the weakness of the PE-coated steel pipe used in the existing ballast pipe was prepared. The test samples are BRE(Basalt fiber reinforced epoxy), BRP(Basalt fiber reinforced unsaturated polyester), GRE(Glass fiber reinforced epoxy), and GRP(Glass fiber reinforced unsaturated polyester). And then it was immersed in NaOH for 720 hours. The friction test of each specimen was conducted. The Friction coefficient analysis according to material friction depth and interfacial adhesion behavior between resin and fiber were analyzed. As a result, the mechanism of interfacial separation between resin and fiber could be analyzed. In the case of the unsaturated polyester resin with low interfacial bonding strength the longer the immersion time in the alkaline solution, the faster the internal deterioration caused by the deterioration that started from the surface, resulting in a decrease in the friction coefficient. It is hoped that this study will help to understand the degradation behavior of composite materials immersed in various chemical solutions such as NaOH, acid, and sodium hypochlorite in the future.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.93-97
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• 1999

In order to lower the surface energy of unsaturated polyester(UPE) resin, small amount of siloxane-ester copolymers were incorporated. The copolymers were synthesized by a condensation polymerization using ethylene glycol and hydroxy termintated polydimethylsiloxane as diols and maleic anhydride and phthalic anhydride as dibasic acids. The modified UPE resin surface was characterized by dynamic contact angle (DCA), peel strength measurements of pressure sensitive adhesives and X-ray photoelectron spectroscopy(ESCA). As the copolymer content in the blend and PDMS content in the copolymer are increased, both advancing and receding contact angles against water are increased. The strength required to peel-off the pressure sensitive adhesive tape from the modified UPE resin decreased dramatically with the addition of the copolymer. ESCA results indicated that polydimethylsiloxane segments are predominated at the outer surface of the modified UPE resin.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.4
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• pp.719-741
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• 1997

This study was undertaken to compare by Atomic Force Microscope the effects of various finishing and polishing instruments on surface roughness of filling and veneering composite resins. Seven composite resins were studied : Silux Plus (3M Dental Products, U.S.A.), Charisma (Heraeus Kulzer, Germany), Prisma THP (L.D.Caulk, Dentsply, U.S.A.), Photoclearfil (Kuraray, Japan), Cesead (Kuraray, Japan), Thermoresin LC (GC, Japan), Artglass (Heraeus Kulzer, Germany). Samples were placed and polymerized in holes (2mm thick and 8.5mm in diameter) machined in Teflon mold under glass plate, ensuring excess of material and moulded to shape with polyester matrix strip. Except control group (Polyester matrix strip), all experimental groups were finished and polishied under manufacturer's instructions. The finishing and polishing procedure were : carbide bur (E.T carbide set 4159, Komet, Germany), diamond bur (composite resin polishing bur set, GC, Japan), aluminum-oxide disc (Sof-Lex Pop-On, 3M Dental Products, U.S.A.), diamond-particle disc (Dia-Finish, Renfert Germany), white stone bur & rubber point( composite finishing kit, EDENTA, Swiss), respectively. Each specimens were evaluated for the surface roughness with Atomic Force Microscope (AutoProbe CP, Park Scientific Instruments, U.S.A.) under contact mode and constant height mode. The results as follows : 1. Except Thermoresin LC, all experimental composite resin groups showed more rougher than control group after finishing and polishing(p<0.1). 2. A surface as smooth as control group was obtained by $Al_{2}O_{3}$ disc all filling composite resin groups except Charisma and all veneering composite resin groups except Thermoresin LC(p<0.05). 3. In case of Thermoresin LC, there were no statistically significant differences before and after finishing and polishing(p>0.1). 4. Carbide bur, diamond bur showed rough surfaces in all composite resin groups, so these were inappropriate for the final polishing instruments.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.324-327
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• 2004

In this paper, fundamental properties of Polymer Concrete made from unsaturated polyester resin based on recycled PET and recycled aggregate(RPC) were investigated. Resins based on recycled PET and recycled aggregate offer the possibility of low source cost for forming useful products, and would also help alleviate an environmental problem and save energy. The results of test for resin contents and recycled aggregate ratio are showed that the strength of RPC increases with resin contents relatively, however beyond a certain resin content the strength does not change appreciably, and the relationship between the compressive strength and aggregate contents at resin $9\%$ has a close correlation linearly whereas there is no correlation between the compressive strength and the flexural strength of RPC with recycled concrete aggregate.

• Textile Coloration and Finishing
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• v.16 no.3
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• pp.22-30
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• 2004

The polyester fabrics were treated with the chitosan with various solubility in optimized treatment condition. The treatment method was discussed to be a high functional finishing for the polyester fabric to obtain the high moisture absorption and anti-microorganism property by evaluating the effect of the chitosan purification method on the yield and anti-microorganism property of the chitosan. On the other hand, soluble polyurethane was added to the chitosan treatment solution and/or plasma pretreatment was done. The addition of soluble polyurethane give a high add-on ratio as well as a linen like effect of treated polyester fabric. The results were as follows: 1. In the treatment of polyester fabric by the chitosan solution, a soluble PU resin and low temperature plasma treatment were done to obtain high binding force between the fabrics and the chitosan. The add-on rate and the moisture absorption ratio of the fabrics treated with the chitosan-PU after treated with the plasma slightly increased more than those of the fabrics treated with the chitosan only. 2. Anti-static property of the fabrics treated with the chitosan decreased rapidly with increasing of the chitosan concentration. The washing fastness of the fabrics treated with the chitosan-PU after treated with the plasma was better than those of the fabrics treated with chitosan only. The wrinkle resistance of the treated fabrics decreased constantly with the concentration of the chitosan. The bending rigidity of the treated fabrics increased greatly. On the treatment of polyester fabric under optimum condition, the microorganism reduction rate kept above 90％ after 10times launderings. 3. As the polyester fabrics which has flat yam was used as a weft yams were treated with the chitosan-PU as give a functional finishing effects such as durability, moisture absorption, anti-static and anti- microorganism property. Treated polyester fabric showed a good functional finishing effect and a linen like property.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.330-335
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• 1998

This research was conducted to evaluate the adhesion in tension of the polymer mortars for cement concrete repair. Various polymer types, binder ratios, and wet/dry conditions of the surface were considered in this study. Styrene-butadiene rubber (SBR) and ethylen vinyl acetate (EVA) used for polymer cement mortars. Epoxy resin (EP), and unsaturated polyester resin (UP) were used for polymer mertars. Adhesion in tension for the dry condition of the substrate surface was higher than that for the wet condition of the substrate surface under the same binder ratio. Therefore, in repairing concrete, the dry surface condition was effective on adhesion.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.189-192
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• 2001

Resin transfer molding process has been widely used in the automobile industry, because the product with large area can be manufactured easily and the cost for the manufacturing is lower than that of compression molding and hand lay up method. Since RTM process is suitable for large bus housing panels, in this work, the composite housing panel was manufactured by RTM process and the mechanical properties, surface quality and the condition of manufacturing process were studied.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.04a
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• pp.1-4
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• 1990

This study was conducted to evaluate strength characteristics of various polymer concretes which were produced using materials available in Korea. Compressive strength, splitting tensile strength and flexural strength were evaluated in this study. Eight different polymer binders were used, including two types of epoxy resin, five types of unsaturated polyester resin, and a type of MMA monomer. The results of this study showed that the product made from PC-100 of SH company was the best performing concrete. However, since this result was based on strength and economics point of view, further study has to be conducted for comprehensive analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.292-295
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• 2004

Recently, polymer-clay hybrid materials have received considerable attention from both a fundamental research and application point of view. This organ-inorganic hybrid, which contains a nanoscale dispersion of the layered silicates, is a material with greatly improved thermal and mechanical characteristics. Two classes of nanocomposites were synthesized using an unsaturated polyester resin as the matrix and sodium montmorillonite as well as an organically modified montmorillonite as the reinforcing agents. X -ray diffraction pattern of the composites showed that the interlayer spacing of the modified montmorillonite were exfoliated in polymer matrix. The mechanical properties also supported these findings, since in general, tensile strength, modulus with modified montmorillonite were higher than the corresponding properties of the composites with unmodified montmorillonite. Adding organically modified clay improved the tensile strength of unsaturated polyester by $22\%$ and the tensile modulus of unsaturated polyester was also improved by $34\%$.