High-performance Rubber Composites Research Articles

Conductive carboxylated styrene butadiene rubber composites by incorporation of polypyrrole-wrapped halloysite nanotubes

Polypyrrole-wrapped halloysite nanotubes (PPy@HNTs) are prepared by polymerization of pyrrole on the surfaces of HNTs. PPy@HNTs show improved dispersion ability and stability in water compared with pure PPy due to the increased zeta potential. The PPy@HNTs dispersions are compounded with carboxylated styrene-butadiene rubber (xSBR) latex to prepare conductive xSBR/PPy@HNTs composites. The morphology, conductive performance, mechanical properties, and swelling performance of the xSBR/PPy@HNTs composites are determined. PPy@HNTs can be uniformly dispersed in the rubber matrix and form a conductive network. The conductivity of the composites increases with the loading of PPy@HNTs. When the content of PPy@HNTs is 10%, the conductivity of the xSBR rubber increases to 1.82 × 10−4 s/m which is much higher than the corresponding xSBR/neat PPy composites (4.62 × 10−8 s/m). Also, the composites show significantly improved mechanical properties both in static and dynamic condition. The tensile strength, Young's modulus, and storage modulus of the composites are substantially higher than those of pure xSBR. The rigid filler networks effectively limit the mobility of rubber molecule chains, which leads to decreased water swelling capacity and crosslink density. The prepared high performance rubber composites with good conductivity show promising applications in many areas such as piezoresistive sensor.

Synergistic Effect of Clay Platelets and Carbon Nanotubes in Styrene–Butadiene Rubber Nanocomposites

Nanoscale materials have provided a big advantage for enhancing the performance of rubber composites through leading the synergy effects in the physical and chemical properties. Here, the authors prepare hybrid fillers using a simple solution‐based method, based on electrostatic interactive assembly, of hydroxyl‐functionalized exfoliated montmorillonite (FE‐MMT) and cetyl trimethylammonium bromide‐modified multiwall nanotube (MWNT). The driving force of hybridization is due to specific interaction between the positive charge on the MWNT and the negative charge of hydroxyl group on MMT. To improve their dispersion, the obtained hybrid fillers are then co‐coagulated with styrene–butadiene rubber (SBR) latex to prepare elastomeric composites. Homogenous dispersion of the hybrid nanofillers in the SBR matrix results in a remarkable improvement in mechanical properties such as modulus (0.31 MPa) and tensile strength (75 MPa) at low loadings. Moreover, the prepared composite of hybrid nanofillers and rubber in the SBR matrix exhibits outstanding thermal (0.3779 W m−1 K−1) and electrical conductivities (15 kΩ) and gas barrier performance (9.16 × 10−45 m4 s−1 N−1). The synergistic reinforcement of SBR achieved by the combined incorporation of MWNT and MMT makes it ideal for use in conscious tires. This research opens up a wealth of new opportunities to prepare high performance rubber composites for future engineering applications. image

Styrene butadiene rubber/clay nanocomposites for tire tread application

Homogeneous and stable dispersion of layered silicates in their rubber nanocomposite is a matter of interest as it can significantly affect the material properties. Herein we propose a facile and easily industrialised approach for preparing highly dispersed montmorillonite (MMT)/rubber nanocomposites by the latex compounding method. Furthermore, an efficient way of enhancing the interlayer spaces of organically modified MMT (f-MMT) with alkyl-ammonium chains while mixing the styrene butadiene rubber (SBR) is reported. The f-MMT embedded SBR matrix shows a remarkable improvement of the modulus and tensile strength even in the low loading rate, which is ascribed to the well dispersion of the f-MMT enhancing interfacial interaction with the rubber matrix. Furthermore, we manufactured the practical pneumatic tire using f-MMT/SBR nanocomposite with outstanding wear resistance, grip performance and low-rolling resistance for the green tire application, opening up enormous opportunities to prepare high-performance rubber composites for future engineering applications.

Constructing a segregated graphene network in rubber composites towards improved electrically conductive and barrier properties

A simple and effective approach, i.e. pre-construction method, was developed to fabricate a three-dimensional segregated graphene network (IL-3DGE) in a styrene butadiene rubber (SBR) matrix. Such segregated 3D-GE network dramatically enhanced the electrical conductivity, mechanical properties and gas barrier property of SBR composites. With the incorporation of 1.66 vol% IL-3DGE, the electrical conductivity of the composites was significantly enhanced by 10 orders of magnitude, the tensile strength was increased by 516%, and gas permeability was effectively reduced by 75.5%, as compared with those of neat SBR. Specifically, SBR/IL-3DGE with a segregated morphology showed a much low electrical percolation threshold (0.39 vol%), which is approximately 9-fold lower than that of the non-segregated SBR/IL-GE (3.78 vol%). The excellent properties of the composites were attributed to the construction of a 3D segregated conductive structure and strong interfacial interactions. This work provides a new insight into the fabrication of high-performance rubber composites for versatile practical applications.

Styrene butadiene rubber/carbon black composites modified by imidazole derivatives

ABSTRACTIn this study, the imidazole derivatives such as 2-undecylimidazole (UI) and 2-mercapto-1-methylimidazole (MMI) are utilized to work as novel additives for modifying styrene butadiene rubber (SBR)/carbon black (CB) composites. The imidazole groups on UI and MMI can be hydrogen-bonded with oxygen-containing groups on the surface of CB, and the undecyl or thiol groups can be reacted with the SBR chains via physical entanglement or thiol-ene chemistry. The results demonstrate that the static and dynamic mechanical performances of SBR/UI and SBR/MMI composites are significantly improved over those of the SBR composite. Compared with blank SBR composite, the tensile strength, modulus at 300% elongation, and tear strength of SBR/MMI-1.0 are greatly improved by 30, 42, and 18%, respectively. The rolling resistance of SBR/MMI-1.0 is reduced by 10.4%, and the wet grip property is increased by 4.0%. The superiority of appropriate MMI content (1.0 phr in our work) in the enhancement for the overall performance of SBR composites is attributed to the promotion of a good dispersion of CB throughout the SBR matrix and the enhanced interfacial interactions between CB and the SBR matrix. This work may enlarge the potential applications of modified CB to fabricate high-performance rubber composites.

Morphology and performance of styrene butadiene rubber filled with modified graphite nanoplatelet and carbon black

In our work, effects of 2-mercapto-1-methylimidazole modified graphite nanoplatelet (MMI–GN) and carbon black (CB) on static and dynamic mechanical properties of styrene butadiene rubber (SBR) composites were studied. MMI–GN is synthesized by ball-mill process, and the result reveals that π–π interactions existed between MMI and GN. The results demonstrate that the static and dynamic mechanical performances of SBR/CB/MMI–GN composites are significantly improved over these of SBR/CB and SBR/CB/GN composites. Compared with SBR/CB, the tensile strength, tear strength, and modulus at 300% elongation of SBR/CB/MMI–GN–3 are greatly improved by 45%, 27%, and 4%, respectively. And the rolling resistance of SBR/CB/MMI–GN–3 is reduced by 3.7% with remaining almost unchanged in the wet grip property. The superiority of MMI–GN in the enhancement for the overall performance of SBR/CB composites is attributed to the well dispersion of GN throughout the SBR matrix and the enhanced interfacial interactions between GN and the SBR matrix. This work might expedite synthesis of the graphite-based materials for enhancing rubber composites, and enlarge the potential applications of modified graphite to fabricate the high-performance rubber composites. Copyright © 2016 John Wiley & Sons, Ltd.

Influence of dispersion of nanofillers and interface interaction on dynamic performance of rubber composites

With increasing concerns in energy saving and environmental protection, the green tire with low rolling resistance, low heat build-up, and high wear resistance have drawn extensive attention in tire industry and academic community. In order to meet the requirements of green tire, the development of high-performance rubber composites with high dynamic properties and outstanding abrasion resistance is critical. However, the balance between the “magic triangle” of tire tread properties (wet resistance, rolling resistance and abrasion resistance) is challengeable due to many influencing factors. In this review paper, we mainly discuss the effects of the dispersion of nanofillers and interface interaction between nanofillers and rubber on the dynamic properties of the rubber composites. Particularly we have discussed the regulation of wet resistance and rolling resistance by using tan δ value at temperature of 0°C and 60°C as the measurement indexes.

Enhanced oil resistance and mechanical properties of nitrile butadiene rubber/lignin composites modified by epoxy resin

ABSTRACTThis is probably the first report on developing nitrile butadiene rubber (NBR) composites with enhanced performancesvia lignin bridged epoxy resin in the rubber matrix. NBR/lignin masterbatch has been prepared through latex‐compounding method, and then epoxy resin (F51) was added in the NBR/lignin compounds by the melt compounding method. Lignin‐epoxy resin networks were synthesizedin situduring the curing process of rubber compounds through epoxide−hydroxyl reactions. Compared with lignin filler, lignin‐F51 networks showed an improved oil resistance ability and led to increased mechanical properties, crosslinking density, and thermal stability of the rubber composites. This method provides a new insight into the fabrication of novel interpenetrating polymer networks in rubber composites and enlarges the potential applications of lignin in high performance rubber composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 42922.

A method to improve the mechanical performance of styrene-butadiene rubber via vulcanization accelerator modified silica

Abstract Accelerator ethylenethiourea (ETU) was chemically grafted onto the surface of silane modified silica (m-silica) to obtain ETU-modified silica (silica-s-ETU). Silica-s-ETU could be homogeneously dispersed into the matrix of styrene-butadiene rubber (SBR) with fairly strong filler-rubber interaction and the grafted ETU molecules were still able to accelerate the sulfur vulcanization. Owing to the improved modification effect, the prepared SBR/silica-s-ETU nanocomposites showed more excellent mechanical properties than SBR/m-silica and SBR/silica nanocomposites containing equivalent accelerator component. Based on the results of immobilized polymer layer, the strengthening mechanism of silica-s-ETU was analyzed and substantiated. The highlight of this work lies in the fact that apparent improvement has been achieved by the surface modification of silica with vulcanization accelerator, which may open up new opportunities for the preparation of high performance rubber composites.

High Performance Graphene Oxide Based Rubber Composites

In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications.

Influence of mineral fillers on stabilizer consumption in rubbers

There has been ever raising concern in last few decades about the utilization of biomass for different commercial applications such as filler materials in rubber composites. In this context, an interesting pathway has been proposed to develop such composites by introducing waste lignin as a reinforcing constituent in high cis-polybutadiene rubber (BR). With a judicious selection of rubber curing ingredients and, simultaneously, adopting suitable solid-state mixing protocols, particularly, a relatively high-temperature multi-steps melt-mixing process (above the glass transition temperature of lignin), rubber composites with an outstanding mechanical performance were prepared. The reinforced rubber composites with 50 (weight) parts lignin loading per hundred parts of rubber (phr) offer ∼10 MPa tensile strength (TS), ∼276% elongation at break (EB), and ∼3.51 MPa tensile stress at 100% elongation (so-called rubber modulus M100). These values are superior when compared with the composites comprised with standard reinforcing carbon black (∼8.5 TS, ∼224% EB, ∼2.79 M100) and even with a silica-silane system (∼7.34 TS, ∼229% EB, ∼2.44 M100) with same filler loading. The unique combination of the curing packages and four-stage mixing process allowed us to establish a homogeneous and fine dispersion of lignin. Furthermore, this is the first time that available models of rubber reinforcement are applied to the description of the reinforcement mechanisms of lignin in a soft elastomer involving various aspects like filler-filler interaction, rubber-filler interactions, critical strains for destroying the filler-filler network, effective filler volume fractions, shape factor, etc. The developed compounding methods for BR and their characterization and modeling can be easily applied to other commercial rubbers facilitating a real breakthrough in developing cheap and bio-based high-performance rubber composites.