Properties Of Styrene-butadiene Rubber Compounds Research Articles

Substantial reduction of carbon black and balancing the technical properties of styrene butadiene rubber compounds using nanoclay

Carbon black is the prime component used in tyre manufacturing. Normally, 40–60 phr of carbon black is added in rubbers to enhance their physico-mechanical properties. Utilisation of high amounts of carbon black during tyre manufacturing will certainly lead to more fly loss, which may create several health hazards to humans involved in the mixing operation. This research work aims to partially replace carbon black with minimal nanoclay and balance the technical properties of styrene butadiene rubber (SBR) compounds. Organically modified polar nanoclay namely, Cloisters 30B was used in this study. Compatibility between SBR and Cloisite 30B was enhanced by introducing carboxylated styrene butadiene rubber (XSBR) as compatibiliser. Compatibilised SBR nanocomposites were developed by means of a two-step mixing process, where the required quantity of Cloisite 30B was dispersed in XSBR through a solution mixing technique. Further, the dried XSBR-Cloisite 30B films were incorporated in the bulk SBR matrix along with carbon black and curing agents through a mechanical mixing technique. For comparison, carbon black filled SBR compounds and dual filler (carbon black and cloisite 30B) filled uncompatibilised SBR compounds were prepared directly via a mechanical mixing method. Cure characteristics, morphology, wear behaviour and mechanical properties were analysed for the prepared rubber compounds. Compatibilised styrene butadiene rubber nanocomposite containing a dual filler exhibited an increase in maximum torque, tensile strength, modulus of elasticity, storage modulus and resistance to wear proving to be potential candidature for tyre applications. The obtained results confirmed that a minimal quantity of nanoclay (3.5 phr) and carbon black (20 phr) contributed to achieve desired technical properties of SBR compounds. In addition, it was observed that the addition of carbon black enhances the distribution of nanoclay bybreaking the nanoclay agglomerates in the SBR matrix, which indeed elevates the technical properties of the related compounds.

Particle packing in bimodal size carbon black mixtures and its effect on the properties of styrene-butadiene rubber compounds

Particle packing, together with other filler characteristics, can be considered as an important structural parameter of fillers, affecting on the properties of rubber compounds. For this purpose, N220 and N550 carbon blacks with nearly similar structure and surface chemistry but different particle sizes were selected. N220/N550 showed the maximum packed density at the composition 35/65 according to the accepted theory for bimodal packing of spheres. A correlation between the packing behavior of carbon blacks mixtures and physical, electrical and rheological behaviors of filled rubber compounds was investigated. A synergic effect in compounds properties was observed before the vulcanization reaction at the maximum packed composition of carbon-blacks. The synergic effect was attributed to the dense and highly immobilized rubber trapped inside packed structure of carbon blacks aggregates, but it didn't appear for the vulcanizates due to the adverse effect of immobilized rubber on the chemical cross-link density formed during vulcanization reaction. • Particle packing is an important structural parameter in rubber reinforcement. • There is a correlation between particle packing and the properties of filled rubber compounds. • A synergic effect in properties was observed at the maximum packed composition of fillers before vulcanization. • The synergic effect was due to the highly immobilized rubber trapped in the filler network. • The synergic effect was absent in some properties after vulcanization.

Utilisation of Zinc Dimethacrylate as Coagent in Sulfur-Peroxide Dual Vulcanisation with Different Sulfur Systems for Styrene-Butadiene Rubber Compounds

The influences of zinc dimethacrylate (ZDMA) contents and three different sulfur systems, i.e. conventional, semi-efficient, and efficient vulcanisations or CV, semi-EV and EV, respectively on crosslink densities and comparative properties of styrene-butadiene rubber compounds containing a fixed amount of peroxide used as an additional crosslinkerwere investigated. The results of cure characteristics and total/specific crosslink densities in different linkage types clearly confirm that, besides synergistic effect of ZDMA towards improved peroxide cure, the extraordinary ionic crosslinks can be generated by this substance, leading to considerable rises in modulus and strength of vulcanisate. However, its ionic-crosslinking efficiency is potentially lessened with increasing sulfur proportion. Elasticity indicated by loss tangent and heat build-up of vulcanisate increases with increasing ZDMA contents due to a higher total crosslink density. The overall properties of CV-based compounds have shown to be independent on ZDMA loading levels. Semi-EV and EV systems provide superior thermal ageing resistance to the vulcanisate compared to CV system due to a greater proportion of short crosslinking bonds: mono-/disulfidic, and carbon-carbon linkages, in EV and semi-EV cured stocks. In addition, the increment of ZDMA contents appears to improve heat-ageing properties of the vulcanisate, attributed to a better thermal stability of ionic crosslinks.

Interaction between 3-aminopropyltrimethoxysilane and oil palm ash in styrene butadiene rubber compounds using response surface methodology

Oil palm ash (OPA) is available in abundance and is renewable. The effects of a combination of OPA and 3-aminopropyltrimethoxysilane on the properties of styrene butadiene rubber (SBR) compounds based on their mixing ratios were studied using response surface methodology. The cure characteristics and tensile properties were selected as the responses. The significance of these factors and their interactions were analysed using ANOVA. The results showed that the presence of OPA and AMPTES had a significant effect on the properties of SBR compounds, whereby all the responses had R2 of above 0.9. This indicates that the regression model is accurate in describing and predicting the pattern of significance for each factor studied. In addition, with the highest level of AMPTES (6 phr) and OPA (80 phr) in the SBR, the tensile strength of the mixture was significantly improved by 151.6% compared to that of gum SBR compound. These findings were further supported by scanning electron microscopy.

Effect of Fly Ash as Filler in Rubber – A Comprehensive Study of the Vulcanisate Properties of Styrene-Butadiene Rubber Compounds

The effect of fly ash as a filler for an ESBR-based compound was studied in the range 0-80 phr. Characterization of fly ash, as received, revealed the abundance of 200 mesh size particles with an average diameter of 10 μm; composition analysis showed the predominance of silica and alumina.The properties of ESBR compounds filled with fly ash particles of ≤200 mesh were compared with those of clay- and whiting-filled compounds. The cure rate index remained unchanged for fly ash throughout the range of loading studied here; clay showed a lower cure rate, and whiting showed a higher value than fly ash. The 300% modulus values did not show any improvement with increase in fly ash loading, the values being comparable with those for whiting and inferior to those for clay. Fly ash gives the lowest heat build-up and tan delta (at 70°C) values among the three fillers under discussion.

Rheological and Mechanical Properties of Styrene-Butadiene Rubber Compounds

The cure behavior, rheological property, and tensile strength of styrene-butadiene rubber (SBR) compounds containing different sizes of rubber powder vulcanizates (RPV) were investigated by varying the loading from 0 to 40 phr. Six different sizes of RPV were selected to see the effect of particle size. A typical reclaimed rubber powder was also used to see the reclaiming effect. The average particle size of the RPVs ranged from 70 to 2,000 μm. In the cure characteristics, as the powder loading was increased, the maximum torque, scorch time, and optimum cure time decreased, while minimum torque increased. At lower shear stresses (or shear strains) the viscosity of the rubber compounds increased noticeably with the addition of RPV. This increase was diminished at higher shear stresses. However, the die swell decreased when RPV was added. With increased powder loading the tensile strength decreased dramatically at lower powder concentrations, ∼ 10 phr, and then the rate of this decrease became slower at higher concentrations. A power-law relation was observed between the tensile strength reduction and the particle size of the RPV.