• 대한기계학회논문집A
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• 제33권4호
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• pp.321-328
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• 2009

Shock absorption performances of various rubbers were investigated by using drop impact test. Several types of rubber such as NR, NBR, EPDM, SR and PUR with three respective levels of shore hardness were used for the test. As in the cases, the absorbed impact energies in rubbers were measured under seven different loads against impact energy between 5-80J. The impact absorption efficiencies of the rubbers then were evaluated by means of both single impact energy condition and summation of all impact energy applied condition. As shown in the results, PUR and EPDM have better shock absorption performances than other rubbers. Further analysis was extended to determine a shear modulus of SR through the finite element implementation with Blatz-Ko model. As can be seen, relatively higher level of absorption energy results in a decreasing shear modulus.

• 한국산학기술학회논문지
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• 제11권4호
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• pp.1197-1202
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• 2010

우리는 자동차 엔진을 지지하기 위한 고무에 대한 마찰특성을 연구하였다. 본 논문은 실험실에서 개발된 테스트 장비를 사용하여 여러 고무의 마찰 마모 특성을 실험적 연구에 의해 분석하였다. 마찰특성은 하중과 온도, 속도 등과 같은 여러 가지 조건 하에서의 마찰력과 수직하중으로부터 측정되었다. 따라서 자동차는 물론 각종 구조용으로 사용되어 지고 있는 고무는 여러 조건에 따라 마찰특성의 관계를 연구하였다.

• Korea-Australia Rheology Journal
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• 제11권4호
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• pp.293-304
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• 1999

Refinements of classical theories for entangled or crosslinked polymeric systems have led to incommensurable models for rubber networks and polymer melts, contrary to experimental evidence, which suggests a great deal of similarity. Uniaxial elongation and compression data of linear and branched polymer melts as well as of crosslinked rubbers were analyzed with respect to their nonlinear strain measure. This was found to be the result of two contributions: (1) affine orientation of network strands, and (2) isotropic strand extension. Network strand extension is caused by an increasing restriction of lateral movement of polymer chains due to deformation, and is modelled by a molecular stress function which in the tube concept of Doi and Edwards is the inverse of the relative tube diameter. Up to moderate strains, $f^2$ is found to be linear in the average stretch for melts as well as for rubbers, which corresponds to a constant tube volume. At large strains, rubbers show maximum extensibility, while melts show maximum molecular tension. This maximum value of the molecular stress function governs the ultimate magnitude of the strain-hardening effect of linear and long-chain branched polymer melts in extensional flows.

• 한국안전학회지
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• 제15권4호
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• pp.41-46
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• 2000

Silicone rubbers are elastomeric materials and organic copolymers, of which backbone is siloxane with high bonding strength. Silicone rubbers have been used as an power insulator because they are well weather proof, ozone proof and have excellent electric characteristics, thermal stability, cold resistance and low surface energy. Especially, it is known that they have very excellent characteristics at 200[$^{\circ}C$]. For this study, we made silicone rubbers as specimens and measured volume resistivity due to applied voltage and a variation of temperature 25[$^{\circ}C$] to 180[$^{\circ}C$]. Also we measured dielectric loss tangent due to applied voltage at temperature range 25[$^{\circ}C$] to 180[$^{\circ}C$] and frequency range 20[Hz] to 1${\times}10^6$[Hz].

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.779-782
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• 2000

Silicone rubbers are first silicone polymers and has named silicone from existence of Si-O bond similar to Keton. Silicon in organic compound has been called silicone, and linear or network polymers. Silicone rubbers have been used as an power insulator because they are well weather proof, ozone proof and have excellent electric characteristics, thermal stability, cold resistance and low surface energy. Especially, it is known that they have very excellent characteristics at 200[$^{\circ}C$]. For this study, we made silicone rubbers as specimens and we measured dielectric loss tangent due to applied voltage at temperature range 25[$^{\circ}C$] to 180[$^{\circ}C$] and frequency range 20[Hz] to 1${\times}$10$\^$6/[Hz] to examine dielectric properties. We measured dielectric loss tangent to study the insulation performance of silicone rubbers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.503-506
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• 2004

In this paper we investigated the changes of surface hydrophobic characteristics on silicone rubbers by corona discharge treatment and also investigated the distribution and the behavior of low molecular weight(LMW) silicone fluid which was extracted by solvent-extraction with gel permeation chromatography(GPC). It was shown that contact angle was $110.5^{\circ}$ on initial sample but contact angle was approximately decreased to $10^{\circ}$ after 45 minutes. However the surface hydrophobic characteristic on silicone rubbers which were removed from corona discharge was recovered within 5 hours. It was shown that corona discharge insured the increase of diffusible LMW chains, which could lead to recover the surface hydrophobicity. The surface hydrophobic characteristics on silicone rubbers and the recovery mechanism based on our results were discussed.

• Elastomers and Composites
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• 제34권2호
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• pp.177-182
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• 1999

SBS thermoplastic elastomers offer an inexpensive alternative to vulcanised rubbers for many undemanding applications. They are, however, particularly susceptible to attack from atmospheric ozone leading to cracking as soon as any strain is applied. In most rubber applications some strain is unavoidable. In this paper a compounding approach to protecting SBS thermoplastic rubbers against ozone is described. An explanation is offered for why a protective effect Is observed only when certain combinations of additive are used. SBS elastomers are the most affordable class of thermoplastic rubbers. To achieve finished products resistant to ozone and without compromising the light colours often demanded, recourse must be made to blending with other saturated elastomers or replacement by hydrogenated (SEBS) types. The latter is a significantly more expensive alternative. Under laboratory conditions where the rate of ozone attack is increased by several decades, unprotected SBS begins to crack within a few hours. Several different protective agents are examined here, the best of which, a cyclic enol ether, $Vulkazon^{(R)}$ AFD, can extend the resistance to any cracking to several weeks by the use of a few percent by weight of additive. The systems reported neither discolour the polymer nor stain other materials with which it may be in contact. Use of the protective systems described here could enable SBS elastomers to compete in many applications with the more expensive SEBS polymers.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.152-162
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• 2005

Coolant rubber hoses for automobile radiators can be degraded and thus failed due to the influence of contacting stresses of air and coolant liquid under the thermal and mechanical loadings. In this study, test analysis was carried out for evaluating the degradation and failure mechanisms of coolant hose materials. Two kinds of EPDM rubber materials applicable to the hoses were adopted: commonly-used ethylene-propylene diene monomer(EPDM) rubbers and EPDM rubbers with high resistance against electro-chemical degradation (ECD). An increase of surface hardness and a large reduction of failure strain were shown due to the formation of oxidation layer for the specimens which had been kept in a high temperature air chamber. Coolant ageing effects took place only by an amount of pure thermal degradation. The specimens degraded by ECD test showed a swelling behavior and a considerable increase in weight on account of the penetration of coolant liquid into the skin and interior of the rubber specimens. The ECD induced material softening as well as drastic reduction in strength and failure strain. However EPDM rubbers designed for high resistance against ECD revealed a large improvement in reduction of failure strain and weight. This study finally established a procedure for reliability analysis and evaluation of the degradation and failure mechanisms of EPDM rubbers used in coolant hoses for automobile radiators.

• 한국염색가공학회지
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• 제35권1호
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• pp.8-19
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• 2023

Silicone rubber is widely used in most industries due to diverse advantages like heat stability, UV stability, durability, chemical resistance, environment friendliness, inertness and so on. But there is limitation to expand applications due to relatively weak rubber strengths such as tensile strength and tear strength, especially in fabric coating applications. The purpose of this study is to find influence of coating agent on performances of rubber and coated fabrics and their correlation according to different crosslinking densities of silicone rubbers. Addition cure type of silicones were formulated using crosslinked MQ-type silicone resin consisting of M (R₃SiO_1/2) and Q (SiO_4/2) and linear polymers. Raw materials used were; 1) linear vinyl endblocked polymers and vinyl functional MQ resin as main polymers, 2) linear silicone hydride polymers as crosslinkers, 3) platinum catalyst and 4) inhibitor to control curing speed. Rubber specimens were prepared to check mechanical strength using universal testing machine (UTM). Crosslinking density was calculated using Flory-Rhener equation using solvent swelling method. Differential scanning calorimetry (DSC) and scanning electron microscope (SEM-EDS) were used to characterize rubbers. Consequently, it was found that physical properties of silicone rubbers and coated fabrics can be expected by crosslinking density of rubbers. Silicone rubber formulations that contain 20 ~ 30 wt% of vinyl MQ resin showed strongest balanced performances.

• 한국자동차공학회논문집
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• 제10권3호
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• pp.166-175
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• 2002

Tank track rubbers, which undergo dynamic stresses and strains under various road conditions, leads to a result of considerable internal temperature rise due to the heat generation. Since rubber materials are not fully elastic, a part of the mechanical energy is converted into heat because of the hysteresis loss. Heat generation without adequate heat dissipation leads to heat build-up, i.e. internal temperature rise which, if excessive, exerts a bad influence upon the performance and the life of the tank track rubbers. The purpose of this paper is to predict temperature distributions of the rubber components off tank track subjected to complex dynamic loads under various read conditions. In steady state analysis temperature fields are displayed in contour shapes, and in unsteady analysis the temperature variations of some important nodes are represented graphically with respect to the running time of the tank.