• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.565-572
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• 1996

The optimum loading of carbon black was studied for the rubber compounds of natural rubber(NR), butadiene rubber(BR), and styrene-butadiene rubber(SBR) with different amount of oil. The optimum loading of carbon black was determined by the volume ratio of carbon black and L factor of Lee's theory. The optimum loading of carbon black was confirmed by the examination of physical properties of the rubbers. The optimum loading amounts of carbon black for the each rubber compound were 60 phr for NR, 57 phr for BR, 65 phr for SBR-A, 70 phr for SBR-B, and 76 phr for SBR-C, respectively. The optimum loading of carbon black was increased by 5 phr for every increment of 20 phr of oil content. It was revealed that the optimum loading amount of carbon black determined by L factor is closely related to the tensile strength of the rubber compounds. The optimum loading amount of carbon black was observed at the amount which shows the maximum value of tensile strength.

• Polymer(Korea)
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• v.33 no.5
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• pp.435-440
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• 2009

Thermal degradation behavior of CR (chloroprene) -modified NR (natural rubber) compounds, having different sulfur/accelerator compositions, was studied by non-isothermal TGA method. Data were analyzed using both Kissinger and Flynn-Wall-Ozawa analysis to assess the activation energies. Activation energy obtained from Kissinger analysis was $147.0{\pm}2.0$ kJ/mol for all samples, showing little effect of sulfur/accelerator composition changes in the samples. On the other hand, activation energy from Flynn-Wall-Ozawa analysis exhibited much variations with conversion, showing average value of $211.6{\pm}19.0$ kJ/mol. From the results, it was considered that whole thermal degradation processes of the samples were composed of complex multiple step processes, of which reaction mechanisms were different from each other.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.403-409
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• 2009

In the 1840s, Goodyear found out sulfur cure system, but cure time was too slow. So producing of rubber product takes a long time. In 1904, Oenslager et al. found that aniline is accelerated sulfur cure system. Recently, many rubber industries needed high yield and good quality. So, many researchers have studied a rubber system with fast vulcanization time and good mechanical properties. In this study, cure characteristics and mechanical properties of NR/BR compounds by accelerator with MBTS(2,2' Dithiobisbenzothiazole), TMTM(Tetramethylthiuram Monosulfide), ZDMC (Zinc dimethyldithiocarbamate), CBS(N-Cyclohexyl benzothiazolyl-2-sulfenamide), DPG(Diphenylguanidine) were evaluated. The results of the study indicate that cure charateristics($t_{90}$: 235 sec, $T_{max}$: 5.77 Nm) and mechanical properties (100, 300% modulus : 2,180, 5.656 Mpa and tear strength: 59.58 kgf/cm) of NR/BR compounds shows efficient acceleration with MBTS 1.5 phr, TMTM 0.5 phr, DPG 0.15phr. This is due to the synergistic activity of ternary accelerator system in rubber vulcanization.

• Elastomers and Composites
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• v.41 no.2
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• pp.88-96
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• 2006

The self-sealing rubber material for a fuel cell which has self-sealing ability, in case of fuel leakage, was studied. Cure characteristics, density, swelling, and surface morphology of foamed natural rubber were investigated with carbon black and with processing oil within the range of $10{\sim}30phr$. The rheological properties indicated that the value of $ts_2$ and the value of $Tc_{90}$ were increased with increasing a content of processing oil, while carbon black did not show a similar trend. A difference in density by foaming was decreased to one fifth scale compared to the initial value. According to the swelling test of foamed natural rubber in fuel C, isooctane and toluene, all the self-sealing action was finished in two minutes. From the SEM image for the surface of rubber compounding, a foaming by sodium bicarbonate was found to be unequal and consecutive foaming cell.

• Elastomers and Composites
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• v.56 no.4
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• pp.223-233
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• 2021

In this study, epoxidized liquid isoprene rubber (E-LqIR) was used as a processing aid in a silica-filled natural rubber compound to improve the fuel efficiency, abrasion resistance, and oil migration problems of truck and bus radial tire tread. The wear resistance, fuel efficiency, and extraction resistance of the compound were evaluated according to the molecular weight of E-LqIR. Results of the evaluation showed that the E-LqIR compound had a lower chemical crosslink density than that of a treated distillate aromatic extract (TDAE) oil compound because of the sulfur consumption of E-LqIR. However, the filler-rubber interaction improved because of the reaction of E-LqIR with silica and crosslink with the base rubber by sulfur. As the molecular weight of E-LqIR increased, crosslink with sulfur was facilitated, and the filler-rubber interaction improved, resulting in improved abrasion resistance. The fuel efficiency performance of the E-LqIR compound was poorer than that of the TDAE oil compound because of the low chemical crosslink density and hysteresis loss at the free chain end of E-LqIR. However, the fuel efficiency performance improved as the molecular weight of E-LqIR increased.

• Elastomers and Composites
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• v.46 no.1
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• pp.70-77
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• 2011

A new piece of test equipment, the slurry wear tester (SWT), was proposed in this study to evaluate the wear behavior of rubber vulcanizate in environmental contact with slurry. Natural rubber (NR) and chloroprene rubber (CR) were chosen as the basic matrices to test the slurry wear. The fluids used to fill the chamber of the SWT were 35% HCl and NaCl solution. The Akron abrasion test was used for comparison with SWT. According to the results of the Akron abrasion test, CR vulcanizate abraded more rapidly than NR vulcanizate under same test condition. It was found that the hysteresis of rubber was key factor contribute to the wear behavior. However, the slurry wear rate of the NR and CR vulcanizates did not change significantly, even with changes in the concentration of acid and the immersion time in both HCl and NaCl solutions; the fluid decreased the friction between the abrasive paper and the specimen. It also reduced the heat generated from repeated deformation and wear debris at the surface of the SWT's abrasion arm. Thus, these phenomena affected the wear behavior of rubber vulcanizate and caused different results in the conventional Akron abrasion test. This outcome could have resulted in an incorrect analysis if the slurry wear behavior of the rubber vulcanizate was estimated by the conventional abrasion tests, which are operated under dry conditions.

• 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.47 no.1
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• pp.23-29
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• 2012

The silica-silica interaction parameter (${\alpha}_F$) of the silane treated silica filled natural rubber (NR) compound was investigated. As silane (TESPT) concentration increased from 2 to 12% (2, 4, 6, 8, 10, 12%), the ${\alpha}_F$ value increased at the same silica concentration (10, 20, 30, and 40 phr). It seemed the sulfur atoms in TESPT acted as a crosslinking agent in the compound. As silica concentration increased from 10 to 40 phr, the ${\alpha}_F$ value increased at the same silane concentration due to increased silica-silica interaction.

• Elastomers and Composites
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• v.47 no.1
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• pp.18-22
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• 2012

The silica-silica interaction parameter (${\alpha}_F$) of the silane treated silica filled natural rubber (NR) compound was investigated. The measured ${\alpha}_F$ values using mass fraction method following Wolff's theory were compared with volume fraction method. As silica concentration increased, the ${\alpha}_F$ value increased for both methods. The value of ${\alpha}_F$ expressed as volume fraction was higher than that of mass fraction, which resulted in large gaps between ${\alpha}_F$ values. The effect of accelerator (MBT) concentration on ${\alpha}_F$ values was compared.

• Polymer(Korea)
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• v.38 no.3
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• pp.406-410
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• 2014

Zinc ion containing thiuram type accelerator zinc dibutyldithiocarbamate (ZDBC) was compared to other thiuram type accelerators (tetramethylthiuram disulfide (TMTD) and dipentamethylenethiuram tetrasulfide (DPTT)) in silica filled natural rubber (NR) compound upon vulcanization and mechanical properties (modulus, tensile strength, and elongation %). ZDBC added compound showed the fastest cure time (t10) and the highest reinforcement index (R.I.) among them and showed a marching behavior. The mechanism was reviewed and a new mechanism was proposed.