Tire Tread Materials Research Articles

NITROGEN-CONTAINING SILANE COUPLING AGENTS: SYNTHESIS AND STRUCTURE EFFECT ON TIRE PERFORMANCE OF SILICA/SSBR/BR COMPOSITES

ABSTRACT We report synthesis of nitrogen-containing silane coupling agents (N-SCAs) and their use in a 1:1 mixture by weight with bis(triethoxysilylpropyl)tetrasulfide preparation of silica/solution SBR (SSBR)/BR composites. These N-SCAs contain in their structures, inter alia, a tertiary amine center (N1, N2), a carbamate (N3), or a urea (N4) group. In addition, N1, N3, and N4 were equipped with allyl side arms to increase the hydrophobization effect of silica particle as well as to achieve a balance between the filler–filler and filler–matrix networks being formed. By contrast, N2 consists of glycidyl side arms that contribute to the filler–filler interaction even more. The silica/SSBR/BR blends and subsequent vulcanizates were prepared and then thoroughly investigated via dynamic mechanical analysis, rubber process analysis, and tensile testing. The composite based on N1 (V/N1) exhibited exceptionally great tensile strength, abrasion resistance, and winter traction, accompanied by soft hysteresis. Therefore, N1 has potential applications in preparation of winter tire tread materials.

DEVELOPMENT OF HYDROGENATED SBR-BASED VULCANIZATE WITH SUPERIOR TIRE TREAD PERFORMANCE

ABSTRACT Currently, the tire industry is exploring eco-friendly tires with improved rolling resistance, traction, abrasion resistance, and fatigue properties. The present study investigates the potentiality of the hydrogenated styrene butadiene rubber (HSBR), a special and modified grade of styrene butadiene rubber (SBR) as a tyre tread material. The rheological, mechanical, dynamic mechanical, abrasion resistance, fatigue resistance, aging resistance and ozone resistance properties of the developed HSBR-based composites were critically evaluated and compared with those of conventional rubbers such as natural rubber (NR), emulsion styrene butadiene rubber (ESBR) and solution styrene butadiene rubber (SSBR) based composites. Interestingly, the HSBR-based vulcanizates exhibited superior modulus, tensile strength, abrasion resistance, fatigue crack growth resistance, resistance to thermo-oxidative aging, and ozone resistance as compared to the conventional SBR–based vulcanizates. The modulus at 300% elongation of the HSBR-based vulcanizate was approximately 74% and 11% higher than that of the ESBR- and SSBR-based composites, respectively, whereas the improvements in tensile strength were approximately 88% and 64% and the improvements in abrasion resistance were approximately 250% and 200% than that of the ESBR and SSBR vulcanizates, respectively. The tensile strength and fatigue resistance characteristics of the HSBR vulcanizate were also nearly similar to those of the NR vulcanizate. The findings demonstrate that HSBR can be a potential tire tread material with robust physico-mechanical properties and durability.

Sensitivity analysis of truck tire tread material properties for on-road applications

This research delves into the sensitivity analysis of a truck tire rubber compound concerning its impact on tire–road interaction characteristics. Initially, the study employs finite element analysis to model a 315/80R22.5 truck tire, which is subsequently validated through static and dynamic response assessments via various simulation tests. Following validation, the established tire model is utilized to conduct a sensitivity analysis of the tire rubber compound specifically applied on the tread. This analysis encompasses several material definitions, including Mooney–Rivlin, visco-Mooney–Rivlin, linear viscoelastic, and nonlinear viscoelastic materials. By exploring the effects of these material models, the research scrutinizes their influence on tire–road interaction characteristics across diverse operating conditions. The tire–road interaction characteristics include the rolling resistance coefficient, and the cornering force at operating conditions including the longitudinal speed, vertical load, and slip angle. This comprehensive investigation offers insights into the intricate relationship between tire composition and performance, thereby enhancing our understanding of tire behavior and informing potential advancements in tire technology.

THERMALLY CONDUCTIVE DURABLE STRAIN SENSORS FOR NEXT-GENERATION INTELLIGENT TIRES FROM NATURAL RUBBER NANOCOMPOSITES

ABSTRACT A substantial knowledge gap persists in the material development of smart tires for future self-driving automobiles, which can increase both the vehicles' performance as well as the safety of the passengers. Due to the very high stiffness of conventional strain sensors compared to the softer rubber compound used as the tire tread material, an inaccurate representation of tire deformation characteristics is anticipated. Here, a comprehensive characterization of the electrical conduction and strain sensing behavior of a natural rubber (NR)-based commercial tire tread composite combining the reinforcement of a carbon black-conductive nanofiber dual filler system was carried out for the very first time. The incorporation of as low as 2 wt.% of carbon nanotubes (CNT) and graphite nanofibers (GNF) could increase the electrical conductivity of the control compound by two orders of magnitude compared to the control compound. The gauge factor observed was much higher than the value reported for metallic or polyvinylidene difluoride (PVDF) based stain sensors developed for this application. A 25% enhancement in thermal conductivity was also observed. Thus, the developed composites have the potential to be used as in situ strain sensors so that the problems of debonding and heating differences in the sensor–rubber interfaces in tires can be avoided in future.

A systematic study of the effect of graphene oxide and reduced graphene oxide on the thermal degradation behavior of acrylonitrile-butadiene rubber in air and nitrogen media

Thermal degradation of acrylonitrile-butadiene rubber (NBR)-graphene oxide (GO)/reduced graphene Oxide (G) composites (NBR-GO/G) was studied in air O2(g) and nitrogen N2(g) media at ∼800°C, using Thermal Gravimetric Analysis (TGA/DTG). The char yield of the composites was high the in N2(g) medium. This was associated with lower weight loss (%) and higher maximum degradation temperatures, Tmax(°C). Doyle simple kinetic approach was used for the first time to estimate the degradation kinetics of the NBR-GO/G composites and large amounts of activation energy Ea (KJ/mol) was observed, particularly for the NBR-GO composites. In O2(g) medium, severe degradation of NBR occurred irrespective of the GO/G-filler content. This suggested that insignificant char yield was produced to protect the scission of the NBR backbone, as decomposition of the main chain seemed to have been accelerated by the high oxygenated moieties (C–O–C, –O–C=O and O–H) decorating GO/G-sheets. For instance, NBR showed ∼89, ∼21 and ∼86 % weight residue, Wr (%) than G0.1, G0.5 and G1 respectively and ∼154, ∼350, ∼92 % higher than the respective GO0.1, GO0.5 and GO1 samples. Although, NBR-G recorded higher Wr(%) than NBR-GO, NBR-GO generally slowed the degradation of NBR than NBR-G composites, possibly due to the presence of high concentration of interactions (NBR—Sx—GO—S—NBR and NBR—O—Hσ+—N σ−—C—NBR) which raised the Ea (KJ/mol) barrier for decomposition. The high thermal stability and compression set (%) properties of NBR-GO/G composites obtained as compared to pure NBR indicated that solution processing techniques used in this current work was very effective than those compounded with melt mixing methods or with GO/G-functionalized nanoparticles. Therefore, this present study provides insights on tailoring rubber-graphene based materials for thermally harsh and high pressure applications such as; oil/gas drilling hose, oil/gas seals, gasket and tire tread materials.

Preparation of bio-based elastomer and its nanocomposites based on dimethyl itaconate with versatile properties

As the need for renewable and high-performance alternative elastomer grows, efforts have been made to develop bio-based elastic polymers for engineering applications. Herein, bio-based elastomers poly(dimethyl itaconate-co-butadiene)s (PDMIBs) were successfully synthesized by emulsion copolymerization of renewable monomer dimethyl itaconate (DMI) with partially petroleum-derived butadiene under mild conditions. It is an effective strategy to tailor PDMIB properties by comonomers with different feed ratios and to adjust the compositions and sequence distributions. The structure and thermal stability were investigated by FTIR, NMR, DSC analyses, etc. In terms of properties: (1) the vulcanizates showed excellent tensile strength (10.2 MPa), elongation at break (1146%) and toughness (37.6 MJ m−3) without filler reinforcement, which were obviously superior to the mechanical properties of most traditional petroleum-based synthetic rubbers; (2) Nanosilica-filled PDMIBs exhibited good mechanical properties, excellent abrasion resistance and oil resistance due to strong polarity in molecular chains; (3) Epoxy-functionalized poly(dimethyl itaconate-co-butadiene-co-glycidyl methacrylate) PDMIBG showed better silica dispersion and excellent dynamic mechanical properties. In summary, this new kind of bio-based elastomer PDMIBs can be used in multiple engineering applications, such as bio-based gloves, conveying belts, oil-resistant products and high-performance tire tread materials, etc. This study opens the door to the use of emulsion copolymerization and functionalization modification technology in the synthesis of new high-performance bio-based elastomer nanocomposites for the rubber industry.

Constructing Chemical Interface Layers by Using Ionic Liquid in Graphene Oxide/Rubber Composites to Achieve High-Wear Resistance in Environmental-Friendly Green Tires.

The harm caused by small rubber particles generated from tire abrasion to the atmosphere is receiving a continuing concern. For developing environmental-friendly tire tread materials with high wear resistance, building the strong interface between nano-fillers and rubber matrix is the primary challenge. Herein, ionic liquid (IL, 1-allyl-3-methylimidazole chloride) was used to modify graphene oxide (GO) by π-cation interaction and hydrogen bonding between IL and GO. Furthermore, an IL-GO/natural rubber (NR) masterbatch possessing fine dispersion of GO was prepared by the emulsion compounding method, and thereafter, a further compound with solution polymerized styrene butadiene rubber (SSBR) was fabricated for the tread rubber composite. Results showed that the double bond in the IL enhanced the cross-linking reaction during the vulcanization of rubber composites occurred at high temperature, leading to an elevated interfacial interaction between the IL-modified GO and the rubber macromolecules. Compared with silicon dioxide (SiO2)-filled NR/SSBR composites, the cross-link density, 300% modulus, and tear strength of the IL-GO/SiO2/NR/SSBR composites were increased by 10.2, 42.6, and 20.2%, respectively. Importantly, the wear resistance of the IL-GO/SiO2/NR/SSBR composites was improved by 17.3%, ascribing to the strong interface between IL-GO and rubber macromolecules.

Double‐layer modified silica with potential reinforcement for solution polymerized styrene‐butadiene rubber/butadiene rubber composite

AbstractSilica was dual layer surface‐capped by hexamethyldisilamide (HMDS) and epoxy‐terminated ethylene‐vinyl acetate copolymer (EVA) via an in situ synthesis route to acquire greatly improved compatibility and interfacial interactions with solution polymerized styrene‐butadiene rubber/butadiene rubber (SSBR/BR). The as‐prepared HMDS/EVA‐SiO2 was used to reinforce SSBR/BR matrix so as to improve the wet skid resistance and wear resistance, and reduce the rolling resistance of the rubber–matrix composite. Besides, the as‐fabricated HMDS/EVA‐SiO2 was characterized by Fourier transform infrared spectrometry and transmission electron microscopy; and the tensile strength and tear resistance of the HMDS/EVA–SiO2/SSBR/BR composites were measured with a universal testing machine. Moreover, an Akron abrasion test was performed to determine the abrasion volume of SiO2–SSBR/BR composites; and a rotary rheometer was run to evaluate the dynamic mechanical properties of the vulcanized rubber‐matrix composites. Findings indicate that the EVA resin latex synthesized by emulsion polymerization can effectively improve the compatibility and forms a permeability layer between the rubber and nano‐silica of the composites. The as‐fabricated HMDS/EVA‐SiO2‐SSBR/BR composite exhibits greatly improved wear resistance and wet skid resistance as well as significantly reduced rolling resistance, showing potential as green tire tread material with increased security and service life as well as reduced energy consumption.

Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS) Quantification of Tire and Road Wear Particles (TRWP) in Environmental Matrices: Assessing the Importance of Microstructure in Instrument Calibration Protocols

Thermogravimetric methods with internal polymer standards have successfully quantified environmental tire and road wear particle (TRWP) concentrations. However, TRWP quantification in environmental matrices via pyrolysis-gas chromatography-mass spectrometry (py-GC-MS) using butadiene rubber (BR) and styrene-butadiene rubber (SBR) marker 4-vinylcyclohexene (4-VCH; 1,4-butadiene-1,4-butadiene dimer) may be uncertain because of variable polymer compositions and BR and SBR microstructures. To determine if tire polymer microstructure is contributing to potentially over- or underestimating TRWP in the environment in py-GC-MS analyses, SBR materials (n = 8) commonly found in tire tread with varying microstructure were quantified via py-GC-MS, using 4-VCH and the deuterated internal standard d-4-VCH to provide a response ratio for each polymer. The response ratios of the dimer response to the total polymer quantity (instrument response slope) varied up to 6.8-fold for SBR, with a reduction to a 3.6-fold range when the polymer quantity was expressed as 1,4-butadiene mass rather than total polymer mass. Variability was reduced further when considering the polymerization method for emulsion-SBRs (n = 3; 1.4-fold range), but not solution-SBRs (n = 5; 2.7-fold range), which reflects the random versus structured heterosequencing of the two rubber types, respectively. Our findings suggest that py-GC-MS response should be interpreted based on empirical analysis of an appropriate number of regionally representative tire tread materials, rather than individual rubbers, because of the lack of methods available for determining unknown average microstructure in environmental samples.

Effect of feldspar filler on physical and dynamic properties of SBR/CB based tire tread compounds: Effect of addition method of silane coupling agent

In this work, the effects of using feldspar (FLD) as an alumina-silicate inorganic filler, with carbon black (CB) as a novel binary filler system, on the properties of SBR compounds were investigated for tire applications. The bis(triethoxysilylpropyl) disulfide (TESPD) was used for modification of FLD. The SBR hybrid composites were produced by replacing 10 phr of CB filler with neat FLD and functionalized FLD (F-FLD). The TESPD was added directly to the rubber mixture including neat FLD. The SBR composite which has only CB filler (50CB) was found to have the highest damping parameter (tan δ) value at 60°C. On the other hand, the composites loaded with the CB and the FLD fillers exhibited relatively lower tan δ at the same temperature showing lower rolling resistance meaning better fuel saving performance. The lowest rolling resistance was achieved for the 40CB-10F-FLD most probably due to its stronger interaction with the SBR elastomer molecules through the silane agent-assisted crosslinks of the F-FLD. As another dynamic property, the storage moduli at −20°C were found to be lower for the SBR hybrid composites as compared to that of the 50CB composite, exhibiting enhanced winter traction performance of the composites having FLD filler together with CB. The composites containing only 10 phr of FLD and F-FLD, on the other hand, exhibited very low tensile strength values which are not acceptable for tire tread materials.

Facile strategies for green tire tread with enhanced filler-matrix interfacial interactions and dynamic mechanical properties

Developing high-performance “green” tire tread material with superior balanced integrated properties is of vital importance in view of environment, resource and energy consideration. In this work, effective and facile strategies concerning macromolecular functionalization and cross-linkable crystalline component incorporation have been proposed to fabricate tire composite materials with balanced integrated performances. The polymer phase structures, filler dispersion, filler-polymer interfacial interactions, and the performances of the resultant composites were investigated in detail. With the introduction of cross-linkable crystalline component, the rubber blends exhibited complex phase morphology analogous to that in the case of integral rubber beside the existence of crystalline fibrils. Additionally, it was demonstrated that the filler dispersion and filler-rubber interactions were enhanced by the synergistic strategies. Consequently, the resultant rubber composites F-SSBR/BR/TBIR displayed excellent integrated properties, such as 200–288% higher fatigue lifetime, 10–26% lower rolling resistance, 25% higher wet-skid resistance and 6–13% higher abrasion resistance. This work will provide effective method and relevant theoretical basis to the development of high-performance “green” tire composite materials.

Dual Friction Mode Textile‐Based Tire Cord Triboelectric Nanogenerator

AbstractAs vehicles become smarter, an alternative power solution will become increasingly important for future vehicle development. With this context, a triboelectric nanogenerator (TENG) is proposed which fully sits on tires and consists of textile‐based tire materials. Both polydimethylsiloxane‐coated silver textile, serving as an external tire tread material, and nylon woven textile, serving as an internal tire cord material, performing as opposing triboelectric materials, are well adaptable for rolling tires. It is demonstrated that tire material‐based TENG performs at its maximum as it makes mutual contact with the road. The power generation property is characterized under different driving situations such as different tire rotation speeds and varying numbers of devices on the tires. The TENG demonstrates a maximum output voltage and a current of about 225 V and 42 µA, respectively, along with an output power of 0.5 mW at optimum load. The work offers the possibility to not only directly operate minute power‐consuming electronics but also collect power and store it while driving a vehicle.

Effect of temperature on wear performance of aircraft tire tread rubber

Abstract Wear performance of tread rubber directly affect the service life of aircraft tires, especially for lateral sliding and high temperature conditions. Temperature of aircraft tire tread rises rapidly during takeoff and landing due to high-speed friction, which greatly affects the wear performance. Therefore, wear tests of aircraft tire tread materials under different temperatures and slip angles have been carried out; then, wear surface morphology and wear mechanism have been discussed; finally, Further research of wear mechanism has been detailed based on the finite element model of rubber wheel. Results indicate that slip angle has a greatly effect on the wear rate when temperature is lower than 45 °C and slip angle is greater than 10°; wear mechanism is different, when temperature is greater than 65 °C; roughness of wear surface decreases with the increasement of temperature. Besides, wear rate and frictional power density have a good correlation, which lays the foundation for the next work of wear prediction.

Implications of the Use of Silica as Active Filler in Passenger Car Tire Compounds on Their Recycling Options.

Tires are an important vehicle component, as car handling, safety and fuel economy depend for a major part on the tire composition and construction. As a consequence, tires are improved continuously. The most prominent improvement in the recent past was the use of a silica-silane filler system in passenger car tread compounds, instead of traditionally used carbon black. For recycling and re-use of end-of-life car tire rubber one of the most promising recycling methods is devulcanization: re-plasticizing the vulcanized rubber by selectively breaking the sulfur bridges between the polymer molecules. In the present paper, the influence of silica, which is present in the passenger car tires granulate, on both devulcanization and subsequent revulcanization, is investigated. In a step-wise approach it is shown that the presence of silica influences both devulcanization and revulcanization. The best tensile strength of the revulcanizate, using a carbon-black-based revulcanization formulation, was 5 MPa. This could be improved to 6.5 MPa by using 2.8 phr of 1,3-DiPhenylGuanidine (DPG) in the revulcanization formulation. After addition of a silanization step during revulcanization by adding 3.2 phr bis[3-(TriEthoxySilyl)Propyl] Tetrasulfide (TESPT), a silane, to the formulation, the tensile strength of the revulcanizate was further improved to 8 MPa. With these results it is shown that the silica in the granulate can be used to improve the revulcanization properties. To check the benefits of using pure tire tread material for the devulcanization and subsequent revulcanization, of both a carbon black and a silica-based virgin tread compound, it is shown that a tensile strength of the revulcanizate of 13 MPa can be reached. This shows the potential of devulcanized rubber when the various tire components are separated before whole car tire material is granulated as the beginning of the recycling.

Effects of Copolymer Sequence on Adsorption and Dynamics Near Nanoparticle Surfaces in Simulated Polymer Nanocomposites

ABSTRACT We study a simple nanocomposite, consisting of a single spherical nanoparticle in a dense melt of coarse-grained copolymer chains, using molecular dynamics simulations. The polymers contain equal amounts of two monomer types, which differ only in their monomer-nanoparticle interaction (adsorption) strengths, and are placed in a random sequence or in a sequence of alternating blocks with various block lengths. This model is motivated by a need to understand copolymer sequence effects relevant to designing tire tread compounds, given the synthetic ability to adjust copolymer architecture (e.g., amount of blockiness) in styrene-butadiene rubbers and the ability to choose fillers and covering agents that functionalize the filler particles to give them different affinities for the styrene and butadiene monomers (it is also possible to use coupling agents, which form covalent bonds between filler particles and polymer chains). Our simple, generalized model considers linear polymers of uniform length that are not cross-linked, and thus we do not attempt to capture the overall mechanical properties of tire tread materials. Instead, we focus our analysis on how copolymer sequence impacts polymer adsorption on the nanoparticle, known to be a significant factor in determining polymer nanocomposite properties. We find that copolymer sequence impacts both the range and magnitude of the interphase of slowed dynamics surrounding the nanoparticle, with longer block lengths yielding a greater reduction in mobility over a wider region.

Hysteresis friction and nonlinear viscoelasticity of rubber composites

Abstract Evaluation of tire friction is essential from the perspective of enhancing vehicle performance and improving its safety. Earlier investigations have identified rubber adhesion and hysteresis as two fundamental mechanisms underlying tire friction. This contribution aims at analyzing the effect of nonlinear viscoelastic behavior of tire treads on their hysteresis friction coefficient. Tire tread is a composite material made of synthetic or natural rubber reinforced with particles such as carbon black or silica. Hysteresis that refers to energy dissipation during a cyclic deformation is an essential feature of mechanical behavior of rubber composites. The effect of nonlinear viscoelasticity of filled rubbers on the hysteresis friction of tire treads is not well understood. In this contribution, we use an analytical model to predict the hysteresis friction of filled rubbers sliding on a rough surface. The model accounts for the nonlinear viscoelasticity of the slider subjected to finite strains. It will be shown that the kinetic coefficient of friction directly correlates with the magnitude of strain. Comparison of model results against the experimental measurements for tire tread materials reveals that the predicted friction coefficients become comparable with experimental data at large strains (8–10%). This study suggests that the nonlinear viscoelasticity of tire treads needs to be taken into account in order to have a more realistic assessment of frictional performance of tires.

A nano-mechanical instability as primary contribution to rolling resistance

Rolling resistance ranks among the top ten automobile megatrends, because it is directly linked to fuel efficiency and emissions reduction. The mechanisms controlling this phenomenon are hidden deeply inside the complexity of tire tread materials and do elude direct experimental observation. Here we use atomistic molecular modelling to identify a novel nano-mechanical mechanism for dissipative loss in silica filled elastomers when the latter are subjected to dynamic strain. The force-vs-particle separation curve of a single silica particle-to-silica particle contact, embedded inside a polyisoprene rubber matrix, is obtained, while the contact is opened and closed by a cyclic force. We confirm the occurrence of spontaneous relative displacements (‘jolts’) of the filler particles. These jolts give rise to energy dissipation in addition to the usual viscous loss in the polymer matrix. As the temperature is increased the new loss mechanism becomes dominant. This has important technical implications for the control and reduction of tire rolling resistance as well as for many other elastomer composite applications involving dynamic loading.

Morphology and performance of NR/NBR/ENR ternary rubber composites

Abstract Epoxidized natural rubber (ENR) was used as a compatibilizer to prepare ternary composites with natural rubber (NR) and nitrile butadiene rubber (NBR). The morphological, structural, and mechanical properties of the NR/NBR/ENR ternary composites were systematically investigated by using SEM, AFM, TEM, DSC, DMTA, and tensile testing. The NR matrix was the continuous phase, and NBR was the dispersed phase with a size of several micrometers. ENR reduced the aggregation of the NBR phase and improved the compatibility between NR and NBR. According to the rule of “like dissolves like”, with increasing polarity, ENR migrated from the NR matrix and was dispersed into the NBR phase or gathered at the interface between NR and NBR. Compared with pure NR, the ternary composites had a higher tan δ at 0 °C and lower tan δ at 60 °C, related to the wet grip and rolling resistance of tread materials, respectively. The results also indicated that the prepared NR/NBR/ENR ternary composites exhibited improved tensile strength and tear strength because of the strain-induced crystallization of NR. Therefore, the NR/NBR/ENR ternary composites are promising high-performance tire tread materials.

Ignition, Heat Release Rate and Suppression of Elastomeric Materials

The focus of this paper is to determine flammability characteristics of rubber materials that are common to vehicle tires, conveyor belts, and electrical power cable insulation and to compare the thermal magnitude of cargo quantities of these materials to other fuels that are publicly transported. Although a literature review was performed, very little data was fo und on this topic. Standard flammability test procedures were used to measure the critical flux for ignition, critical ignition temperature, and heat release rates (HRR) of rubber compounds common to tire tread materials and conveyor belt covers. Both the intermediate scale calorimeter: ISO 14696, ASTM E-1623 (ICAL) and the cone calorimeter: ISO E-5660, ASTM 1354 (Cone) provided the bulk of the data. Critical ignition flux and vertical flame spread data for rubber based electrical insulations were determined using a radiant panel from a modified ASTM flame spread apparatus: ASTM E-162. thermogravimetric analysis was also used to evaluate thermal decomposition progression of selected test materials. Further, suppression tests were conducted on tire piles to evaluate agents to extinguish and control tire fires. Also, the HRR of the tire piles were measured and compared to work performed by others. Results confirm that the area heat release rate of rubber materials is directly proportional to exposure flux intensity. The critical exposure flux for ignition of a variety of rubber-based materials is approximately 20 kW/m2 to 30 kW/m2 and the critical temperature for piloted and non-piloted ignition were independent of exposure intensity at ~400°C and ~600°C respectively. In large quantities, rubber tire loads have total HRR comparable to the heat released from similar areas of liquid hydrocarbon spills.

Study on structure and properties of SSBR/SiO2 co‐coagulated rubber and SSBR filled with nanosilica composites

AbstractThe morphological structure, glass transition, mechanical properties, and dynamic mechanical properties of star‐shaped solution‐polymerized styrene‐butadiene rubber (SSBR) synthesized by a multifunctional organic lithium initiator and SiO2‐SSBR composite (N‐SSBR) prepared through adding a small amount of nanosilica modified by silane coupling agent to star‐shaped SSBR synthetic solution and co‐coagulating, and their nanocomposites filled with 20 phr nanosilica were investigated, respectively. The results showed that the silica particles were well dispersed with nanosize in N‐SSBR, which glass‐transition temperature (Tg) was 2°C higher than SSBR. N‐SSBR/SiO2 nanocomposite exhibited lower Payne effect and internal friction loss, higher mechanical properties, and its Tg was 2°C higher than SSBR/SiO2 nanocomposite. N‐SSBR might promote the dispersion of nanosilica powder in matrix and could be applied to green tire tread materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008