• Elastomers and Composites
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• v.30 no.3
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• pp.218-228
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• 1995

To make filler loaded conducting rubber which has excellent electronical and physical properties, CR and NBR were mixed with barium ferrite(BaO.6Fe2O3). From the result of this study, vulcanization characteristics shows that curve is upgraded as the filler concentration increases and CR has higher torque than NBR. In physical properties, elongation being higher, modulus comes to decrease. Tear strength gradually decrease after showing the maximum point when is in the 100phr in CR. Resilience is not good to cause the increase in filler concentration. In electrical properties, conductivity becomes low when filler concentration increase. The increase of voltage makes a conductivity grown, but the rate change is weak. The influence of temperature hardly changes on increasing temperature. The morphology and the dispersion of a conductivity filler in vulcanizates through SEM were good. The more filler concentration increases, the shorter the particle interval is.

• Elastomers and Composites
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• v.18 no.3
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• pp.87-98
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• 1983

Fundamental properties and surface treatment effects of domestic kaolin calcined at higher temperature were studied to develop reinforcing fillers for rubbers. The results obtained are as follows: (i) X-ray diffraction and scanning electron microscopy studies revealed kaolinite as a major constituent of the raw kaolin used in this study. (ii) Physical properties of natural rubber vulcanizates compounded with the calcined kaolin fillers treated with poly(maleic anhydride) and sodium polyphosphate are favorably improved. Particularly, the kaolin filler treated with sodium polyphosphate(designated as PT series) shows excellent physical properties compared with hydrated silica.

• Macromolecular Research
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• v.9 no.6
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• pp.319-326
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• 2001

Fatigue crack growth (FCG) behavior of natural rubber/ethylene-propylene-diene rubber (NR/EPDM) blend vulcanizates under dynamic tearing condition was investigated by using a fracture mechanics approach. It appeared that variation of crack growth rate with blend compositions was dependent on the level of imposed tearing energy G. At low tearing energy region, the FCG rates of the blend were lower as the EPDM content was increased, while at high tearing energy region, the trend was reversed. Over the measured range of tearing energy G, all blend compositions showed the lower crack growth rates compared to the average of properties of component elastomers. When the blends were thermally aged, the fatigue resistance of the blends was deteriorated in proportion to the concentration of EPDM phase. Fatigue crack growth behavior of the blends was supposed to be associated with the inhomogeneities of the crosslink structure of the blends arising from cure incompatibility of the EPDM and NR when they are sulphur cured.

• Elastomers and Composites
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• v.58 no.1
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• pp.17-25
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• 2023

Abrasion tests of model tire tread compounds (NR and NR/BR blend compounds) were performed at different slip angles (1° and 7°) using a laboratory abrasion tester. The abrasion behavior was investigated by analyzing the worn surface and wear particles. The abrasion spacing formed on the specimen worn at the large slip angle of 7° was significantly narrower than that at the small slip angle of 1°, while the abrasion depth for the specimen worn at 7° was lower than that at 1°. The abrasion spacing and depth tended to be narrower and lower, respectively, as the BR content increased. The abrasion patterns were clearly visible on the outside of the specimen for the slip angle of 1° but not for 7°. The wear particles had a rough surface and there were numerous micro-bumps. It was found that the crosslink density affected the abrasion patterns and morphologies of the wear particles.

• 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.

• Elastomers and Composites
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• v.44 no.3
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• pp.315-322
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• 2009

Influence of blend mode of extender oil on the properties of thermoplastic vulcanizates (TPVs), based on an ethylene-propylene-diene copolymer (EPDM) and a polypropylene (PP), was studied. The EPDM/PP TPVs were prepared in an open roll mill using two different modes in blending sequence of paraffinic oil and phenolic curative, i.e., Oil-Cure and Cure-Oil modes. Degree of cross-linking by gel fraction and properties such as hardness, tensile strength, elongation at break, and melt flow rate were investigated as a function of extender oil content for the two modes. Little influence of the blend mode of extender oil on the degree of cross-linking and mechanical behaviors was observed. However, the use of Cure-Oil mode in the preparation of EPDM/PP TPVs resulted in a marked increase in the level of processability as reflected by melt flow index, as compared to the use of Oil-Cure mode.

• Elastomers and Composites
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• v.31 no.5
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• pp.341-346
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• 1996

The fracture mechanics investigation of the thermoplastic vulcanizates(TPV) from EPDM and PP/Ionomer ternary blends was performed in terms of the J-integral by measuring fracture energy via the locus method. The TPV from ternary blends consisting of EPDM, PP and ionomer were prepared in a laboratory integral mixer by blending and vulcanizing simultaneously. Vulcanization was performed with dicumyl peroxide (DCP) and the composition of EPDM and PP was fixed at 50/50 by weight. Two kinds of poly(ethylene-co-methacrylic acid) (EMA) lonomers were used. The J-integral values at crack initiation, Jc, of the dynamically vulcanized EPDM and PP/EMA Ionomer ternary blends were affected by the cation types $(Na^+\;or\;Zn^{2+})$ and contents(5-20wt%) of the added EMA Ionomers. The ternary blend containing 20wt% zinc-neutralized EMA Ionomer and 1.0phr DCP showed the highest Jc values of the blends.

• Elastomers and Composites
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• v.42 no.2
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• pp.102-106
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• 2007

Water swelling behaviors of SBR vulcanizates with different reinforcing systems of carbon black, silica without a coupling agent, and silica containing a coupling agent were studied. Distilled water and 3.5% NaCl solution were used as swelling media. The water swelling ratios in the distilled water were higher than those in the salt solution. The water swelling ratios of the carbon black-filled samples were lower than those of the silica-filled ones. For the silica-filled SBR vulcanizates, the specimens without the silane coupling agent had higher water swelling ratios than those containing it. Water swelling behaviors of SBR composites with different 1,2-unit contents were also compared. The water swelling ratios tended to decrease by increasing the 1,2-unit content.

• Elastomers and Composites
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• v.35 no.2
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• pp.149-156
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• 2000

trans-octylene rubber(TOR) was melt-blended with an incompatible NBR/EPDM (70/30) blend. Mixing torque and temperature were reduced as TOR was added to the NBR/EPDM blend. Rheometer results indicated that TOR participated in vulcanization and became a part of network. A scanning electron micrograph demonstrated that EPDM was dispersed in NBR matrix in the blend and the addition of TOR led to a finer dispersion of EPDM particles. On the addition of TOR, the tensile strength, the tensile strain as well as the modulus of the blend vulcanizates increased. The ozone resistance of the blends determined in terms of critical stress-strain parameter was significantly enhanced in the blend as TOR was added. Improvements in the properties were believed to be associated with fine morphology and the increase in crosslink density due to the chain entanglement of the ternary blends.

• Elastomers and Composites
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• v.43 no.4
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• pp.281-287
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• 2008

Using solid state $^{13}C$ NMR, polybutadiene rubber vulcanizates were qualitatively and quantitatively analyzed. In the filled conventional system of BR vulcanizate accelerated with TBBS, addition to the olefinic double bond and substitution in the $\alpha$ position to the double bond occurred simultaneously. Also the latter $\alpha$ substitution reaction was faster than the former addition reaction at initial reaction time. In addition, it was suggested that double bond-addition-polysulfide structures might be modified into 5-membered and 6-membered cyclic structures in overcure time. These chain modifications were correlated with the decrease in the chemical crosslink density in overcure time.