• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1115-1120
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• 2000

The purpose of this study is to investigate toughening of unsaturated polyester resin by addition of liquid rubber. In general, unsaturated polyester liquid has strong brittleness in spite of if high strength Therefore; it is difficult use polyurethane liquid rubber for the place where impact resistance is demanded. In this study, it was evaluated strength, impact resistance and fracture toughness by adding to polyurethane liquid rubber(0~25%). As a result, it was found that a tendency to be increase bearing impact and fracture toughness as polyurethane liquid rubber increased but strength was decreased.

• Journal of Environmental Science International
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• v.19 no.3
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• pp.365-370
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• 2010

In this study, we carried out the evaluation of EPDM(Ethylene Propylene Diene Monomer) reclaimed rubber mixing with natural rubber at various mixing ratio to reuse as rubber filler. The scorch time and moony viscosity was analyzed to evaluate the effect of cure behavior. And also, we analyzed the tensile strength, the elongation at break and cure time to evaluate the variation of cure behavior. As the results, the scorch time and optimal cure time was decreased according to the increasing of EPDM reclaimed rubber. However, the moony viscosity was increased at each mixing ratio. In case of the added EPDM reclaimed rubber was 20 phr(parts by weight per 100 parts by weight of rubber), the hardness and specific gravity was increased a little. The hardness and specific gravity was increased in rapidly under 40 phr of the added EPEM reclaimed rubber. The tensile strength and elongation at break of the compound of natural and EPDM reclaimed rubber was rapidly decreased compared with its natural rubber when the ratio of adding EPDM reclaimed rubber was over 40 phr.

• Elastomers and Composites
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• v.29 no.3
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• pp.226-233
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• 1994

The properties of the mixed prepolymer-urethane in the range of 10-40 phr were observed. LBR and LCR have same functional group but different in structure of molecular. The viscosity of mixture depending on content of rubber, adhesive strength, thermal property and compatibility with a diluted solvent are as follows: 1. The viscosity of the mixture was influenced by solubility of the diluent for urethane resin and liquid rubber. 2. Adhesive strength showed the highest value at 30phr rubber, decreased gradually at above 30phr rubber. And LBR revealed better physical property than that of LCR. 3. The most effective factors affecting adhesive strength are molecular structure of rubber, the type of solvent, and volatility. 4. Urethane resin containing LBR showed better compatibility for solvent and faster drying velocity. 5. LBR showed more favorable compatibility and dispersion state than those of LCR by analyzing the results of SEM.

• Elastomers and Composites
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• v.25 no.3
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• pp.195-202
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• 1990

Rubber-modified polyurethane resin which was prepolymer type terminated with NCO, was synthesized by reacting isocyanate groups[NCO] and hydroxyl groups[OH]. Polybutadiene rubbers which had OH groups in the side of rubber chains, were charged at ratio $0%{\sim}40%$ of solid component in reactants. For products, physical properties were investigated experimentally. The results abtained in experiment were as follows. 1. Liquid resin and dried film was good solubility and clearity at less than 25%, 20% of rubber without being related to sort. 2. G-1000 showed better properties than R-45HT in solubility, dring time and adhesive strength. 3. Dring time and adhesive strength were considerably influenced by molecular weigh and structure of rubber. 4. In using 25% of mixed rubber(G-1000/R-45HT=50/50), It represented best properties in dring time(10 minute) and adhesive strength($23Kg/cm^2$).

• Elastomers and Composites
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• v.39 no.4
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• pp.294-300
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• 2004

Mechanical properties of the commingled waste plastics filled with ground rubber tire were studied. To improve adhesion at the interface, trans-octylene rubber(TOR) was added. With increasing the rubber level, first, due to their inherent incompatibility, the tensile and the compressive strength decreased but tensile strain and impact strength increased. Then, as TOR added, the samples showed still the same strain but the tensile, impact, and compressive strength as well increased markedly Variation of the properties by addition of TOR seemed to be attributed to the dual character of TOR.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.78-81
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• 2004

In this paper, the effect of adhesion properties of semiconductive-insulating interface layer of silicone rubber on electrical properties was investigated. Surface structure and adhesion of semiconductive silicon rubber by surface asperity was obtained from SEM and T-peel test. In addition, ac breakdown test was carried out for elucidating the change of electrical property by roughness treatment. From the results, Adhesive strength of semiconductive-insulation interface was increased with surface asperity. Dielectric breakdown strength by surface asperity decreased than initial Specimen, but increased from Sand Paper #1200. According to the adhesional strength data unevenness and void formed on the silicone rubber interface expand the surface area and result in improvement of adhesion. Before treatment Sand Paper #1200, dielectric breakdown strength was decreased by unevenness and void which are causing to have electric field mitigation small. After the treatment, the effect of adhesion increased dielectric breakdown strength. It is found that ac dielectric breakdown strength was increased with improving the adhesion between the semiconductive and insulating interface.

• Advances in concrete construction
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• v.9 no.3
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• pp.249-256
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• 2020

This paper aims at investigating the effect of crumb rubber size and content on compressive behaviors of concrete under axial compression. Concrete specimens are designed and produced by replacing natural aggregate with crumb rubber content of 0%, 5%, 10%, 15% and three different sized crumb rubbers (No. 20, No. 40, No. 80 crumb rubber). And the failure mode, compressive strength, elastic modulus, stress-strain curves, peak strain and ultimate strain are experimentally studied. Based on the test results, formulas have been presented to determine the compressive strength, elastic modulus, the relationship between prism compressive strength and cube compressive strength, stress-strain curves and peak strain of crumb rubber concrete (CRC). It is found that the proposed formulas agree well with the test result on the whole, which may be used to practical applications.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.878-888
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• 1994

In order to investigate the fracture behavior of ABS terpolymer under the tension and impact load, varing the content of rubber, molecular weight of SAN, content and kinds of lubricant, tension speed, the mechanical properties were measured and SEM pictures of fracture area were taken. Under the tension, the tensile strength increased as rubber content and lubricant content decreased, while molecular weight and tension speed increased. The deformation of area near fracture site did not occur as rubber content, tension speed and molecular weight decreased and liquid lubricant was used. And in the shape of fracture seemed phase seperation. Under the impact load, the notched izod impact strength increased as rubber content, molecular weight, ambient temperature and lubricant content increased. In the SEM picture, the strength was high white the fracture surface was small.

• Elastomers and Composites
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• v.53 no.2
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• pp.80-85
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• 2018

Chloro isobutylene isoprene rubber (CIIR) and ethylene propylene diene monomer (EPDM) compounded with other formulation chemicals, depending on the polymer blend, were prepared by mechanical mixing. After manufacturing the rubber vulcanizate by compression molding with a hot press, the mechanical and thermal properties including thermal conductivity, rebound resilience of the CIIR/EPDM blends were measured. As the EPDM rubber content increased, hardness and tension set showed a tendency to increase. Pure CIIR exhibited the lowest tensile strength; however, tensile strength increased with loading of EPDM rubber. On the other hand, in CIIR rubber, which is usually a low-rebound elastomer owing to a high damping effect, rebound resilience exhibited an increasing trend as the content of EPDM rubber increased. As the EPDM rubber content increased, thermal stability was improved due to reduction of decomposition rate in the rubber region of the blend vulcanizate.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.161-166
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• 2000

To save efforts for capping in the compressive strength tests of concrete, unbonded capping system has been standardized by ASTM C 1231 and AS 1012.9, respectively. These standards, however, do not sufficiently give a full detail of accessories such as steel retaining cap and rubber pad, especially hardness of rubber. Hence, without testing for sizes of steel retaining cap and rubber pad, tests for the quality control of rubber pads were conducted in detail according to Japanese studies. Based on tests, the range of hardness for rubber pad by the compressive strength(200~ 400kgf/$\textrm{cm}^2$) of concrete has been proposed and the guideline of reuses of a rubber pad is described.