• Polymer(Korea)
• /
• v.39 no.2
• /
• pp.240-246
• /
• 2015

Formation of a strong 3-dimensional interfacial network structure via chemical reaction between hydroxyl group on silica surface and NR chain by the addition of bis(triethoxysilylpropyl)tetrasulfide (TESPT) into silica-filled NR compound was observed by using Py-GC/MS and SEM. Addition of TESPT into silica-filled NR compound decreased scorch time ($t_{10}$) due to increased sulfur content, and reduced cure rate index (CRI) via continuous reaction between sulfur atoms in TESPT, which acted as a sulfur donor, and activators and/or accelerators. Addition of TESPT in the compound improved processability and mechanical properties of the compound. Overall, we observed that the addition of TESPT into the silica-filled NR compound formed a silica-TESPT-NR network, and thus the degree of crosslinking was increased resulting in improved mechanical properties.

• Elastomers and Composites
• /
• v.36 no.1
• /
• pp.30-36
• /
• 2001

The objective of this study was to investigate factor that influences the development of anisotropy in carbon black filled natural rubber vulcanizates. Chain orientation affects tensile strength, stiffness. Parallel sample shows low stress at low deformation, but have high stiffness at high deformation compared to isotropic or perpendicular samples. This study shows that natural rubber(NR) exhibits much larger tensile anisotropy at high strains than SBR. It seems that the parallel sample of NR is dominated by orientation effect at high strains. This oriented chain is expected to act as nuclei for following crystallization during second stretching and facilitates the strain-induced crystallization.

• Elastomers and Composites
• /
• v.46 no.3
• /
• pp.237-244
• /
• 2011

Five natural rubber (NR) composites with different reinforcing systems of unfilled, carbon black, carbon black with silane coupling agent, silica, and silica with silane coupling agent were thermally aged and change of the crosslink densities by the accelerated thermal aging was investigated. The crosslink densities on the whole increased as the aging time elapsed irrespective of the reinforcing systems. The crosslink density changes became noticeable by increasing the aging temperature. For carbon black-filled composites, the silane coupling agent made the crosslink density change to be increased. For silica-filled composites, however, the silane coupling agent made the crosslink density increment reduced at 60 and $70^{\circ}C$ and it hardly affect the degree of the crosslink density change at 80 and $90^{\circ}C$. The activation energies for the crosslink density changes of the carbon black-filled samples increased continuously in a logarithmic fashion, whereas that of the silica-filled one showed a quasi-steady state ranges at aging times of 30-150 days. The activation energy of the unfilled sample increased exponentially with the aging time. The experimental results were explained with sulfur donation from the silane coupling agent, surface modification of the filler by the silane coupling agent, adsorption of curative residues on the silica surface, and release of the adsorbed curative residues.

• Macromolecular Research
• /
• v.8 no.6
• /
• pp.268-275
• /
• 2000

After imposing a large pre-strain, anisotropy increases with increasing residual extension ratio. Gums have very low residual extension ratio and exhibit little anisotropy, while black filled SBR and especially sulfur-cured carbon black filled NR have large set and anisotropy. For carbon black filled rubber, samples subjected to tensile loading in perpendicular to the pre-strain direction have the same stress-strain curves shape as the sample without pre-strain (=isotropic samples), but slightly lower modulus. However, compared to isotropic or perpendicular directional samples to pre-strain direction, samples subjected to tensile loading in parallel to the pre-strain direction show low stress at low deformation, but have high stiffness at high deformation. Normalized anisotropy changes with strain. The normalized anisotropy for various deformations is a linear function of residual extension ratio.

• Elastomers and Composites
• /
• v.44 no.2
• /
• pp.134-142
• /
• 2009

Organo bifunctional silane (TESPD) is added into silica containing NR and its effects are investigated with respect to the vulcanization properties, the processability, and the physical properties. The addition of the TESPD into silica filled NR compound increases the degree of crosslinking by formation of a strong 3-dimensional network structure with silica surface via coupling reaction, which results in an improved mechanical property. It also improves the processabilities compared to the Control compound.

• Elastomers and Composites
• /
• v.19 no.4
• /
• pp.231-242
• /
• 1984

NR vulcanizate has its unigue characteristic of cushion, silence, vibration energy absorbtion etc. By reason of the above captioned characters, The vulcanizate has been widely applied to production of auto tires, belts and engine mounts, The purpose of this study is to examine the effect of rubber-filler attachments on the various dynamic properties of the NR vulcanizates. For this study, the elastic modulus and damping values are examined by means of the (RDS) the Good Rich Flexometer. The results of this study showed as follows. The damping values of the vulcaniz ates in the elastic region showed showed strong relations the damping values and the filler characteristics. The vulvanizates filled with carbon black had higher damping values than the vulcanizates loaded with inorganic filler. The Goodrich Flexometer test showed that build up for the silica filled NR vulcanizates was higher than those for which contained other fillers.

• Elastomers and Composites
• /
• v.37 no.2
• /
• pp.86-98
• /
• 2002

The application of silica/carbon black dual phase fillers to natural rubber(NR) compound was investigated. When the amounts of filler content were restricted to 60phr, the optimum ratio of dual phase fillers were 25phr/35phr of silica/carbon black. It was found that these new fillers give better overall performance in comparison with carbon black in tear strength, crack resistance, and cutting resistance. Also the thermal degradation resistance of NR vulcanizates which were filled with dual phase fillers was better than that of the carbon black. Dual phase fillers filled NR vulcanizates showed better viscoelastic properties, like tan${\delta}$, for the wet skid resistance and rolling resistance of motor vehicle tires.

• Elastomers and Composites
• /
• v.44 no.4
• /
• pp.455-465
• /
• 2009

In this study, Organo-montmorillonite(MMT) was synthesized by intercalation of various amine(Octylamine, Dodecylamine, Dimethyldodecylamine, Octadecylamine) compounds into layered silicate. Natural Rubber(NR)/MMT nanocomposites were prepared by reinforcement of Organo-MMT. X-ray diffraction(XRD) and Scanning electron microscope(SEM) were employed to characterize the layer distance of Organo-MMT and the morphology of the NR/MMT nanocomposites. The structures of the synthesized Organo-MMTs were analyzed by the measurement of FT-IR. Cure characteristics, surface free energy and mechanical properties such as tensile strength, modulus and hardness of NR/MMT nanocomposites were carefully studied by contact angle meter, ODR, UTM, and hardness tester. FT-IR analysis showed a insertion of the alkyl and amine chains into the interlayers of the MMT. It was shown that the cure time of the organo-MMT was more decreased than that of $Na^+$-MMT. Surface free energy and tensile strength of the NR/DDA-MMT nanocomposite were the highest. NR/ODA-MMT nanocomposite was the highest in hardness.

• Macromolecular Research
• /
• v.15 no.5
• /
• pp.482-485
• /
• 2007

• Polymer(Korea)
• /
• v.37 no.3
• /
• pp.269-275
• /
• 2013

Thiuram (DPTT, TMTD), thiazole (MBT, MBTS), sulfenamide (CBS, NOBS), and zinc containing thiuram (dithiocarbamate) (ZDBC) type accelerators were added into silica and carbon black filled natural rubber (NR) compounds. Their effects on vulcanization time and rate were compared. The vulcanization rate of thiuram type accelerator added compounds showed the fastest rate, followed by thiazole and sulfenamide types. Silica filled natural rubber (NR) compounds showed a slower vulcanization time ($t_{s2}$, $t_{10}$, $t_{90}$) and lower cure rate index (CRI) than carbon black filled ones upon each accelerator.