• Elastomers and Composites
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• v.38 no.1
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• pp.38-50
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• 2003

This paper describes recent advances in ultrasonic devulcanization technology and the in.Situ ultrasonic compatibilization of the blends of the immiscible polymers by making copolymers at the interfaus and their vicinities and our understanding of the mechanism of these processes.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.622-628
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• 2013

Due to the development of compounding technology, there is a considerable increase in the number of high performance rubbers in the world. Accordingly, there are rapid growing requests about high performance tires such as UHP tire and Run-flat tire. However, it is extremely difficult to investigate the friction coefficient of tire tread rubbers. An alternative solution must be developed with the reliability of high-speed linear friction test machines. The use of friction test machines can be expected to improve rubber friction researches. In this paper, we propose a new kind of high-speed linear friction test machine. We have designed and manufactured various mechanisms for friction tests. The final goals are to design and manufacture friction test machines that can investigate friction coefficients efficiently and rapidly. The performance of the proposed high-speed linear friction test machine is evaluated experimentally; however additional study should be necessary for safer and more reliable experimentation.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.427-431
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• 2017

Recently, complaints of floor noise have been growing up with the rapid increase of the residential buildings. This demands the effective floor noise isolation system. Since the construction of high-rise the residential buildings will be increased even more in future, the noise isolation is a more important technology in the market. In this study, a new floor noise isolation panel (FNIP) was designed and manufactured using waste rubbers. The noise isolation was investigated at both laboratory and field conditions. Light and heavy weight shock wave showed 52 dB and 48 dB in the field test, respectively. The new system could reduce the total floor thickness by 22~42 mm.

• Elastomers and Composites
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• v.31 no.5
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• pp.335-340
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• 1996

In order to look into the internal structure and the properties in the silicone rubbers added reinforcing fillers; silica $additives(O{\sim}140phr)$, and to examine the behavior of charged particles, the properties of thermally stimulated current(TSC) and X-Ray diffraction are investigated, respectively. And then, from the TSC which are formed by applying the electric field of $2{\sim}5kV/mm$ to specimen at the temperature range from -150 to $260^{\circ}C$, the results are as follwing: In the case of non-filled specimen, four peaks of ${\delta},\;{\gamma},\;{\beta}\;and\;{\alpha}$ are obtained at the temperature of $-120^{\circ}C,\;-60^{\circ}C,\;20^{\circ}C\;and\;130^{\circ}C$, respectively and the case of filled specimen, three peaks of ${\delta},\;{\alpha}_2\;and\;{\alpha}_1$ are observed at the temperature of $-120^{\circ}C,\;80^{\circ}C\;and\;130^{\circ}C$, respectively. The origins of these peaks are that, the ${\delta}$ peak seems to the result from the contribution of side chain methyl radical, and the ${\gamma}$ peak from the depolarization of space charge polarization owing to be added impurity during manufacturing specimens, and the ${\beta}$ peak from the orientation of $Si-CH_3$ dipole, and the ${\alpha}_2$ near the temperature of $80^{\circ}C$ from hydroxyl in carboxylic radical, and finally, the ${\alpha}_1$ peak near the temperature of $130^{\circ}C$ from carboxyl acid that is formed by the thermal oxidation of high temperature.

• Journal of ILASS-Korea
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• v.12 no.2
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• pp.94-100
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• 2007

The liquid phase LPG injection (LPLi) system (the third generation technology) has been considered as one of the next generation fuel supply systems for LPG vehicles, since it has a very strong potential to accomplish the higher power, higher efficiency, and lower emission characteristics than the mixer type (the second generation technology) fuel supply system. To investigate the characteristics of LPG residue in liquid phase LPG injection system, various rubbers in LPG fuel system were reacted with LPG fuels during 3 months. The experimental results showed that the residue of a cover rubber in a fuel pump after test increased 10 times higher than that before test. Furthermore, the amount of sulfur, nitrogen species which are considered as main sources in deposit formation in the LPLi fuel injector were also found to be higher than that in original LPG fuel. And rubber properties of fuel pump cover were decreased after reaction test compared with those of the original rubber. Therefore, the rubber for fuel pump cover is not suitable for a proper material in LPLi fuel system. And these results can provide more information if a motor company shares the data of core rubber parts in field test LPLi vehicles.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2345-2350
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• 2011

Variable temperature high-resolution $^{19}F$ magic angle spinning (MAS) solid-state NMR spectroscopy was used to characterize fluorocarbon (FKM) rubbers. The high-resolution spectra of copolymers made from two monomers, vinylidene fluoride and hexafluoropropene, and terpolymers composed of vinylidene fluoride, hexafluoropropene, and tetrafluoroethylene, were obtained using MAS speeds of up to 18 kHz combined with high temperatures of up to 200 $^{\circ}C$ at a magnetic field strength of 9.4 Tesla. From these high resolution solid-state NMR spectra, we were able to assign the spectral peaks and differentiate the copolymer FKM from the terpolymer FKM. We also determined quantitatively the monomer compositions of each FKM rubber.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.123-133
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• 2000

The kinetic analysis was carried out for commercial rubbers such as NR, IR, BR, SBR 1500, and SBR 1700. Kinetic analysis for the commercial rubbers was performed using the thermogravimetric method, with which the activation energies of NR obtained by Kissinger, Friedman, and Ozawa's method were 195.0, 198.3 and 186.3kJ/mol, whereas that of SBR 1500 were 246.4, 247.5 and 254.8kJ/mol, respectively. It was shown that the yield of pyrolytic oil was generally increased with final temperature increasing, yet slightly decreased or increased over $700^{\circ}C$. Considering the effect of heating rate, it was found that the yield of pyrolytic oil was not consistent for each sample. The number average molecular weight of SBR 1500 was in the range of 740~2486. The calorific value of SBR 1500 was 39~40kJ/g, which were made comparative study of the conventional fuel such as kerosene, diesel, light fuel, and heavy fuel. Therefore it was essential that the selection of the suitable kinetic model and the mathematical solution because of the difference in parameters obtained from each method. It was proposed that the range of $600~700^{\circ}C$ in final temperature and high heating rate due to short run time. It was suggested that the pyrolytic oil be available to use to the fuel.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1227-1234
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• 2006

Up to now, several mathematical theories based on strain energy functions have been developed for rubber materials. These theories, coupled with the finite element method, can be used very effectively by engineers to analyze and design rubber components. However, due to the complexities of the mathematical formulations and the lack of general guidelines available fur the analysis of rubber components, it is a formidable task for an engineer to analyze rubber components. In this paper a method for predicting strain energy functions - Neo-Hookean model and Mooney-Rivlin model - from the hardness using the empirical equation without any experiment is discussed. First based on the elasticity theories of rubber, the relation between stress and strain is defined. Then for the butyl rubbers, the model constants of Neo-Hookean model and Mooney-Rivlin model are calculated from uniaxial tension tests. From the results, the usefulness of the empirical equation to estimate elastic modulus from hardness is confirmed and, fur Mooney-Rivlin model, the predicted and the experimental model constants are compared and discussed.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.377-380
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• 2002

Acoustic Characteristics of Nitrile Butadiene Rubber with Carbon Black ContentAcoustic and mechanical properties of Nitrile Butadiene Rubbers (NBR) with the variation of the carbon black content were investigated. NBR where the acrylonitrile content is $33\%$ based on the mole percent has been prepared with fixed sulfur content for vulcanization. Acoustic measurement of the prepared rubbers were peformed in the frequency region of $300\;\~\;1000\;kHz$. Their mechanical properties such as density, hardness were also measured. Increase of the carbon black content in the rubber resulted in enhancement of the mechanical property and linear increase of the sound speed as function of the carbon black content. Interestingly, attenuation of the sound speed was only affected by the existence of the carbon black and not by the amount of carbon black in the experiment range of this article. In this study, it was found that the amount of carbon black content in the NBR was correlated with the acoustic properties and can be estimated nondestructively by the measurement of the specific acoustic property.

• Journal of the Korean Society of Safety
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• v.11 no.2
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• pp.60-66
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• 1996

In order to look into the internal structure and electrical properties of insulating Silicone rubbers added reinforcing fillers ; Silica(0-140 phr ), and to examine the behavior of charged particles, and the properties of thermally stimulated current (TSC) are investigated, respectively. From the TSC which are formed by applying the electric field of 2~5 ㎸/mm to specimen at temperature range from -150 to $270^{\circ}C$, the results arp as following. In the case of non-filled specimen, four peaks of $\delta$, $\gamma$ , $\beta$ and u are obtained at the temperature of $-120^{\circ}C$, $-60^{\circ}C$, $20^{\circ}C$ and $130^{\circ}C$, respectively and the case of filled specimen, three peaks of $\delta$, ${\alpha}_2$ and ${\alpha}_1$ are observed at the temperature of of $-120^{\circ}C$, $80^{\circ}C$ and $130^{\circ}C$, respectively. The origins of these peaks are that, the $\delta$ peak seems to the result from the contribution of side chain methyl radical, and the $\beta$ peak from the depolarization of space charge polarization owing to added imputity during during manufacturing specimens, and the $\beta$ peak from the orientation of $Si-CH_3$dipole, and the ${\alpha}_2$ near the temperature of $130^{\circ}C$ from carboxyl acid that is formed by the thermal oxidation of high temperature.