Elastomer Blend Properties—Influence of Carbon Black Type and Location

Abstract

Criteria for minimizing hysteresis in carbon-black-filled elastomer blends are: (1) large black unit size, wide distribution, and low structure; (2) higher black loading in the discrete polymer phase (large zones); and (3) polymer of lower hysteresis as the continuous phase (low black loading). Of the different strength properties that were evaluated, tear and fatigue resistance showed the greatest dependence on black location in NR-BR and NR-SBR blends. Both properties were markedly higher for NR-BR, with most of the black in the NR phase. In NR-SBR, tear strength was higher with high loadings of black in the SBR. Fatigue life showed a reverse pattern, but the variations were not as great in this system. Criteria for maximizing tear resistance are: (1) small black unit size, low structure; (2) higher loading of carbon black in the continuous polymer phase ; and (3) the polymer of higher strength as the continuous phase. There may also be optimum levels of polymer zone size and black size distribution which affect tear strength. Optimized performance in a 50:50 NR-BR radial truck tire tread stock was obtained with a wide-distribution N-375 (50:50 N-351-N-110 blend) black with 75% location in the NR phase. This black gave 5–6°C lower heat buildup, equivalent modulus, 35% higher tear strength, and almost double the fatigue life of a conventionally mixed N-220 at essentially equivalent tread wear resistance (−4%). Optimized performance in 50:50 NR-SBR was indicated for a wide-distribution N-231 type (50:50 blend of N-351-N-119) with 75% of the black in the SBR phase. In comparison to conventionally mixed N-234 and N-220, this black gave about 8–10°C lower heat buildup, about 15% lower modulus, and essentially equal tensile, tear, and fatigue properties. Alternatively, a standard N-231 type with 75% location in the NR phase showed about 5–6°C lower heat buildup, about 20% lower modulus, equivalent tensile strength, 60% higher tear resistance, and 75–120% higher fatigue life.

Effect of silica reinforcement on natural rubber and butadiene rubber vulcanizates by a sol–gel reaction with tetraethoxysilane

“…The sol–gel reaction of TEOS involves the swelling of a precured rubber in TEOS and then subjection of the TEOS‐swollen rubber to a sol–gel process, that is, hydrolysis and condensation. This application of the sol–gel process to rubber chemistry is somewhat related to the use of silane coupling agents and moisture or silane curing,27 and it has been carried out already on silicon rubber 28. The TEOS contained in the rubber is converted into silica upon hydrolysis and condensation according to the following equation: …”

Effect of filler–filler interaction on rheological behaviour of natural rubber compounds filled with both carbon black and silica

“…Physical properties of rubber vulcanizates are improved by reinforcing with fillers such as carbon black and silica 1–4. The reinforcement by filler enhances the physical properties of hardness, modulus, tensile strength, abrasion resistance, etc.…”

Reinforcing mechanisms of carbon nanotubes and high structure carbon black in natural rubber/styrene-butadiene rubber blend prepared by mechanical mixing − effect of bound rubber

“…This can be attributed to the fact that the SBR forms the continuous phase in this blend. Consistently, Hess and Chirico observed that SBR is the continuous phase in 50/50 blends of NR/SBR. As the two‐phase morphology of the polymer blend is dominated by many parameters such as the molecular weight of the blend constituents and their viscosities, in addition to the blend composition, the observed morphological behavior is understandable.…”