• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.395-399
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• 2011

Material of the gasket for lithium ion battery requires the chemical resistance, the electrical insulting property, the compression set, the anti-contamination level and the low temperature resistance. We compounded ethylene propylene diene monomer (EPDM), which showed widely different solubility parameter index, with adjusting the amount of metal oxide as an activator. We did long-term test and compression set against an electrolyte with consideration for operating conditions in lithium-ion battery. In these tests, we checked the physical, chemical characteristics and the effect to lithium ion battery with different kinds of activators. In case of rubber with ZnO as an activator, through 1000 h depositing test in propylene carbonate which is one of representative solvents, we could get the satisfying characteristics and result. However, $Zn^{2+}$ had eluted in the ion elution test. So, ZnO should be limited in EPDM compound for the gasket material in lithium-ion battery.

• Elastomers and Composites
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• v.35 no.4
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• pp.261-271
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• 2000

Physical properties of NR vulcanizates cured by both sulfur and resole were studied. Cure characteristics of the compounds were also investigated. Two types of resoles with different molecular weight distributions were employed. The scorch time of the NR compound containing the resole with a low molecular weight distribution was shorter than that of the compound containing the resole with a high one. Crosslink densities of the NR vulcanizates with a high resole content after the thermal aging at $95^{\circ}C$ decreased, while that of the vulcanizate without resole after the thermal aging at $95^{\circ}C$ increased. Though crosslink densities of the NR vulcanizates with a high resole content decreased with increasing the aging time, the moduli increased while the tensile strength and tear strength decreased.

• Elastomers and Composites
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• v.50 no.3
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• pp.167-174
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• 2015

Anionic epoxy compound was synthesized and added to asphalt aiming to prepare self-healing asphalt. Epoxy-modified asphalt showed excellent modification effect and healing effect as well. The results revealed that with 5% addition of polymer the tensile strength, impact strength and complex shear modulus of the polymer-modified asphalt increased by 65%. 64% and 35%, respectively. It seems that high interaction occurs between polymer and asphalt matrix. Self-healing efficiency of the polymer-modified asphalt based on tensile strength showed 100%, comparing to 79% of straight asphalt. In impact experiment the polymer-modified asphalt showed 99% of healing efficiency, comparing to 77% of straight asphalt. In rheological experiment the polymer-modified asphalt showed 103% of healing efficiency, comparing to 72% of straight asphalt. It appears that the ionic bonding existing in epoxy polymers contributed to high values of self-healing efficiency. The polymer which has high intermolecular force fills the crack of the asphalt, pulling the opponent side each other, and so the original properties were restored.

• Elastomers and Composites
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• v.41 no.1
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• pp.10-18
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• 2006

Influence of low molecular weight polybutadiene (liquid PB) treated with maleic anhydride on properties of a silica-filled SBR compounds was studied. Silica dispersion was improved by adding liquid PB. The liquid PB treated with maleic anhydride (liquid MAPB) was found to be more effective for the improvement of silica dispersion than the liquid PB without maleic anhydride (liquid NPB). Viscosity of the SBR compound decreased by adding the liquid PB. The crosslink density decreased with increase of the liquid PB content and the cure rate became slower with increasing the liquid PB content. Considering the experimental results, it was believed that addition of small amount of the liquid PB (less than 5 phr) was desirable to improve properties of silica-filled SBR compounds.

• Elastomers and Composites
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• v.36 no.1
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• pp.44-51
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• 2001

To see the effect of chemical surface modification, the carbon black surfaces were treated with three types of chemicals (KOH, $H_3PO_4$, and benzene). Vulcanization and mechanical properties of a styrene-butadiene rubber (SBR) were investigated depending on the chemical treatments. The surface free energy increased considerably with the treatments by both the acid (HCB) and base (KCB), but only a slight increase was observed for benzene treatment(BCB). The BCB showed the highest level of the London dispersive component. The vulcanization reaction was found to be faster in the order of KCB-SBR> BCB-SBR> VCB-SBR(virgin) > HCB-SBR. The difference in minimum and maximum torque of rheocurve, representing the degree of crosslinking, was found to be higher for the BCB-SBR compared to those of VCB-SBR, KCB-SBR, and HCB-SBR. The BCB-SBR and KCB-SBR showed the improved tensile and dynamic mechanical properties. A linear relationship was found to exist between the London dispersive component of surface free energy and mechanical properties.

• Elastomers and Composites
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• v.21 no.1
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• pp.13-19
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• 1986

The effects of several vulcanizing accelerators on the determination of kinetic parameters of natural rubber vulcanizate was studied by DSC. Kinetic parameters were determined by means of the calculation procedures of Borchardt-Daniels and Oscillating Disk Rheometer (ODR) cure curve analysis, using both DSC exothermal thermogram and ODR cure curve. In order to examine the credibility in the DSC method the same compound which was und for DSC method was used for the comparison with the results of ODR data. Upon this method, kinetic rate constant (k), and Arrehenius parameter (Ea, ko, n) have been determined for rubber compounds via a new method using DSC thermogram and ODR cure curve. In the comparison of DSC and ODR results, kinetic parameters has shown good agreements between two results. Consequently, from the present studies, it is shown that the DSC thermoanalytical method can provide an alternate new method of kinetic study of rubber vulcanization.

• Journal of the Korean Society of Radiology
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• v.12 no.6
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• pp.777-783
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• 2018

The purpose of this study was to investigate the degree of tearing of the rubber when the spike of the syringe connector was connected to the bottle of the contrast medium composed of the rubber compound type and to investigate the presence of the synthetic rubber due to tearing and grinding and the size of the pulverized product when the pulverized matters rubber was detected. As a result, in the case of tearing degree, the front side of the first contact with the end of the syringe connector was torn more than the back side by about $3.14{\pm}0.04mm$, and the pulverized matters was detected on average 7 to 15 on the 10 contrast mediums. The average particle size was measured to be about $7.89{\pm}0.31{\mu}m$. In addition, it is necessary to develop a micro_filter type automatic injection system for blocking off the pulverized matters as well as additional experiments through various experiments and analysis methods, and it is considered that interest of related organizations will be needed in preparation of fatal accidents when pulverized matters is introduced.

• Polymer(Korea)
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• v.35 no.3
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• pp.228-231
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• 2011

The rate of vulcanization of nonpolar ethylene-propylene-diene terpolymer(EPDM)/carbon black compounds was investigated by using hot air and microwave as a heating source. The present study parameters such as heating source, sample thickness, and loading of an additive. The compound thickness was the main factor in the hot air vulcanization. It was due to the poor thermal conductivity of EPDM; that is, the thicker thickness, the lower vulcanization rate. For 100% vulcanization, the compound with 3 mm thickness required 7 min at $250^{\circ}C$ in the hot air system. However, the vulcanization of EPDM compounds by microwave system was not affected by the thickness while strongly dependent on the amount of a polar additive, carbon black. A compound with 80 phr of carbon black was perfectly vulcanized within 30 sec. These results suggest that the use of microwave as a heating source is an effective method for the vulcanization of compounds including a polar component.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.419-426
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• 1999

In this study, the reaction rate constant, activation energy, total crosslinking density, elastic constant, cure properties ($t_5,\;t_{90}$), modulus, and abrasion resistance of rubber compounds were investigated as a function of cure temperatures, cure systems and reinforcing filler loadings. Reaction rate constants showed strong dependence on thc carbon black loading, cure temperature and cure system, and increased sharply with increasing the reaction temperatures. The lowest activation energy was obtained in the efficient cure (EC) system which corresponds to the high level of sulfur to accelerator ratio, and the activation energy was decreased with decreasing the carbon black loadings. The change of carbon black loadings directly affects the modulus and abrasion resistance, but the change of cure system showed various effects on the rubber compounds. Increased carbon black loadings showed the high modulus, improved abrasion resistance and short scorch time but decrease in crosslinking density and elastic constant. Higher crosslinking density and elastic constant were shown in the EC cure system regardless of carbon black loadings, but scorch timc ($t_5$) was not affected by the change of the ratio of sulfur to accelerator. Rapid optimum cure time ($t_{90}$) were showen in the EC cure system. Also, the equivalent cure curve coefficient of rubber compound was 0.96 for conventional cure (CC) system, and 0.94 for semi-efficient cure (SEC) and EC system regardless carbon black loadings. As regarding the abrasion resistance, wear volume showed the logarithmic increase for the loaded weight.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.3
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• pp.211-218
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• 1991

The effects of dietary fiber on true digestibility of amino acids by growing pigs were studied, using semi-purified diets formulated from alfalfa meal, cassava leaf meal, rubber seed meal and leucacna meal at 20% level. A protein-free diet including 5% cellulose was formulated for correcting the endogenous amino acid loss. Across all the diets, arginine was the most digestible while the least at ileal level was threonine; methionine and/or histidine at fecal level respectively. The true digestibility value of amino acids at ileal level were higher than at fecal level except control diet (cellulose). The true digestibility values at ileal level were similar for all diets but differed at fecal level in different magnitude. These results indicate that undigestible compound in individual feedstuff might confound. True digestibility should be studied together for accurate diet formulation as apparent digestibility decreased when their amino acid concentration in the diet was reduced.