• Macromolecular Research
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• v.14 no.2
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• pp.187-193
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• 2006

Organoclay, was applied as a filler, in place of carbon black and silica, to a natural rubber (NR)/butadiene rubber (BR) blend. A compounding method was used to disperse and separate the layered silicates. The effect of a coupling agent on the vulcanizates was evaluated using both the silica and organoclay filled compounds. After the compounding processes were completed, the XRD diffraction peaks disappeared, but then reappeared after vulcanization. The scorch times for the organoclay-filled compounds were very short compared to those for carbon black and silica-filled compounds. The organoclay-filled compounds showed high values of tensile strength, modulus, tear energy, and elongation at the break. When ranked by viscosity, the compounds appeared in the following order: silica > silica (Si-69) > organoclay > organoclay (Si-69) > carbon black. Fractional hysteresis, tensile set, and wear rates were very consistent with the viscosity of the vulcanizates. The Si 69 coupling agent increased reversion resistance, the maximum torque values in the ODR, modulus, and wear resistance, but decreased elongation at the break, fractional hysteresis, and tension set of the vulcanizates.

• Elastomers and Composites
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• v.33 no.3
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• pp.159-167
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• 1998

Rubber products are aged like human complexion by the attack of oxygen, ultra violet, ozone, etc.. Aging is very important and also very complicated phenomenon to understand. This may explain the rarity of papers on this subject. In this study, we tried to understand the aging behavior of EPDM compared to that of natural rubber. We also compared the sulfur vulcanized system to the peroxide vulcanized one. In our experiment, the peroxide vulcanizates were more advantageous in aging than the sulfur vulcanizates. The authors belived that this study about the high performance EPDM would be applicable to rubber industry.

• Elastomers and Composites
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• v.50 no.3
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• pp.196-204
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• 2015

Crosslink density of a rubber vulcanizate determines the chemical and physical properties, while bound rubber is an important factor to estimate reinforcement of a filled rubber compound. Extender oil is added to a raw rubber with very high molecular weight for improving processability of a rubber composite. Influence of extender oil on crosslink density, bound rubber formation, and physical properties of solution styrene-butadiene rubber (SSBR) composites with differing microstructures was investigated. Crosslink densities of non-oil-extended SSBR (NO-SSBR) vulcanizates were higher than those of oil-extended SSBR (OE-SSBR) ones. Bound rubber contents of NO-SSBR compounds were also greater than those of OE-SSBR ones. The experimental results could be explained by interfering of extender oil. The OE-SSBR vulcanizates had low modulus but long elongation at break, whereas the NO-SSBR ones had high modulus but short elongation at break. It was found that the crosslink densities affected the physical properties more than the bound rubber contents. The moduli increased with increase in the crosslink density irrespective of extender oil, while the elongation at break decreased. Each variation of the tensile strengths of NO-SSBR and OE-SSBR vulcanizates with the crosslink density showed a decreasing trend. Tear strength of the OE-SSBR vulcanizate increased with increase in the crosslink density, whereas variation of the tear strength of NO-SSBR vulcanizate with the crosslink density showed a weak decreasing trend.

• Elastomers and Composites
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• v.54 no.3
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• pp.209-219
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• 2019

It is important to analyze crosslink densities of rubber articles because the physical properties are dependent on the crosslink densities. In this paper, analytical techniques for the measurement of crosslink densities of rubber vulcanizates are described. The most widely used method to measure the crosslink density is a swelling method combined with the Flory-Rehner equation. Application of the interaction parameter (${\chi}$) of rubber and swelling solvent is critical because the crosslink density is absolutely dependent on the ${\chi}$ value. Methods for obtaining ${\chi}$ employ not only solubility parameters of the polymer and swelling solvent but also inverse gas chromatography (IGC). The solubilities of rubbers can be obtained using micro differential scanning calorimetry (${\mu}DSC$), intrinsic viscosity measurement, and UV-visible spectroscopy. Nuclear magnetic resonance (NMR) spectroscopy has been also used for the measurement of the crosslink density using the $T_2$ relaxation time, which is determined by spin-spin relaxation in solid-state NMR. For sulfur-cured rubber vulcanizates, crosslink densities according to the crosslink types of mono-, di-, and polysulfides are measured by treating the rubber samples with a chemical probe composed of thiol and amine compounds. Measurement methods of physical crosslinking by filler, crystallization, and ionic bonding have also been introduced.

• Elastomers and Composites
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• v.46 no.1
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• pp.45-53
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• 2011

The effect of the silane coupling agent, bis(triethoxysilypropyl)tetrasulfide (TESPT), on mechanical properties of a silica-filled NBR compound for oilseal was investigated. Curing behavior and crosslinking density of the compounds were measured using ODR (oscillating disk rheometer) and swelling ratio in toluene. UTM (universal testing machine) and shore A hardness tester were used in order to study the characteristics of mechanical properties of original vulcanizates and aged ones with heated air and ASTM No. 3. oil. Recovery of elasticity which influences the performance and service life of oilseal was investigated by giving bending deformation to vulcanizates in aging condition. After bending aging test, recovery distance was measured and calculated angle of recovery from it. TR (temperature retraction) test was performed on these vulcanizates to determine the low temperature recovery behavior. Wear resistance was measured by Taber type abrasion tester. In addition, SEM was used to characterize the morphology of the worn surface of vulcanizates. The result showed that addition of TESPT into silica-filled compound improves not only compound flow-ability, interaction between NBR and silica and crosslinking density, but also hardness, 100% modulus, recovery of elasticity, wear resistance, heat resistance and ASTM No.3 oil resistance of vulcanizates.

• Journal of Environmental Science International
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• v.9 no.6
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• pp.511-515
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• 2000

The purpose of this experiment is to prepare ethylene propylene diene terpolymer(EPDM)/ acrylonitrile butadiene rubber(NBR) blend which represents good environmental resistant properties including favorable oil and ozone resistance. With incorporation of EPDM, NBR and other ingredients, the rubber and chemical additives were mixed by mechanical method such as Banbury mixer and open 2-roll mill. Then rubber vulcanizates were manufactured by hot press and mechanical properties, oil and ozone resistance of the test specimens were measured. The oil resistance and ozone resistance of EPDM and NBR, respectively, is remarkably improved by blending EPDM with NBR. The optimum results of oil and zone resistant characteristics were obtained at EPDM/NBR(=25/75 wt%) composition ratio.

• Macromolecular Research
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• v.8 no.6
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• pp.285-291
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• 2000

Influence of silane coupling agent, bis-(3-(triethoxisilyl)-propyl)-tetrassulfide, on cure characteristics and bound rubber content of filled styrene-butadiene rubber (SBR) compounds and on physical properties of the vulcanizates was studied. Carbon black-filled and silica-filled compounds were compared. Content of the bound rubber increased with increased content of the silane coupling agent and this trend was shown more clearly in the silica-filled compounds. Optimum cure time of the carbon black-filled compound increased with increase of the silane content, while that of the silica-filled one decreased. Cure rate of the carbon black-filled compound became slower as the silane content increased while that of the silica-filled one became faster. By increasing the silane content, the minimum torque decreased and the delta torque increased. Physical properties of the silica-filled vulcanizate were found to be improved by adding the silane coupling agent. However, for the carbon black-filled vulcanizates, the tensile strength and tear resistance decreased with increase of the silane content. The differences between the carbon black-filled and silica-filled compounds were explained by difference in the reactivities of the fillers with the silane.

• Elastomers and Composites
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• v.23 no.4
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• pp.299-307
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• 1988

The mono-, di- and polysulfidic concentrations of the carbon black filled NR and SBR vucanizates which have different cure systems were determined. The n-decane was used as a swelling solvent. The propane-2-thiol and hexane thiol were used as specific chemical probes to cleavage the chemical crosslinks such as di- and polysulfide. In order to understand the effect of crosslink structure on the physical properties of vulcanizates, the tensile properties, fatigue failure, heat build up, compression set and viscoelastic properties were measured. From the results, the significant relationships between crosslink sturctures and physical properties, especially a gins resistance were obtained. Therefore, the better performances of the product can be satisfied by using the interpretations and approaches in this study.

• Elastomers and Composites
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• v.55 no.1
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• pp.6-12
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• 2020

Poly(ethylene-co-vinyl acetate) compounds and vulcanizates containing dicumyl peroxide (DCP) (HD) were prepared, and the curing agent and reaction products were analyzed using gas chromatography/mass spectrometry (GC/MS). Samples containing trially cyanurate (TAC) and DCP (HDT) were also prepared and analyzed. Some raw DCP were decomposed in the injector region of GC to produce acetophenone. DCP was detected in the HD compound but was not observed in the HD vulcanizate, and instead acetophenone and 2-phenyl-2-propanol were detected. Both DCP and TAC were observed in the HDT compound but not in the HDT vulcanizate, where acetophenone and 2-phenyl-2-propanol were detected. Thus, some of the DCP decomposed during the compounding process. The formation mechanism for acetophenone and 2-phenyl-2-propanol during the crosslinking reaction was identified, and differences in the crosslinking reactions of HD and HDT compounds were discussed.

• Elastomers and Composites
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• v.55 no.3
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• pp.229-234
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• 2020

Automobile wiper blades are generally treated with chlorine to lower their friction coefficient with the windshield surface. This treatment could affect the crosslink density measurement of rubber vulcanizates, a material used in windshield wipers, which would consequently alter its chemical and physical properties. Therefore, this study evaluated the influence of chlorination on crosslink density measurements of natural rubber (NR) vulcanizates using a vehicle wiper blade. A method for determining the degree of chlorination was developed where the interaction parameter between the rubber and the swelling solvent was corrected. A decrease in the rubber sample swelling ratio was observed upon chlorination, and the chlorination penetrated less than 1% of the sample thickness. The chlorinated NR was assumed to be chloroprene rubber (CR), which was used to correct the interaction parameter. The results showed the CR contributed approximately 7% to the parameter.