Green Tire Research Articles

Liquid 3,4-polyisoprene: A novel processing aid to achieve tire tread SBR composites with high wet grip and low energy consumption

Processing oils are indispensable in the rubber industry. Conventional oils just physically exist in compounds and migrate out of samples over time, which deteriorates the properties of materials and pollutes the environment. In this study, liquid 3,4-polyisoprene (L3,4-IR) has been synthesized, and it can co-cure with matrix to mitigate migration problems. Furthermore, L3,4-IR gives compounds lower Mooney viscosity, reduced Payne effect, and better filler dispersion than conventional treated distillate aromatic extracted (TDAE) oils. Vulcanizates with the high tan δ value at 0 °C and the decreased tan δ value at 60 °C were also obtained using L3,4-IR instead of TDAE oil and commercial liquid polyisoprene or polybutadiene, indicating the better wet-grip and lower rolling resistance properties. Compounds containing L3,4-IR also exhibit higher thermal stabilities and better abrasion resistance than sample containing TDAE oils after thermal aging. The excellent properties obtained in this work make L3,4-IR a strong candidate for developing the next generation of green tires with high performance.

Effect of silica dispersed by special dispersing agents with green strategy on tire rolling resistance and energy consumption

AbstractThe state‐of‐art approach to realize the low rolling resistance of green tires is the high addition of SiO2. However, its dispersion capacity and the interface strength with rubber dominant the final properties of green tires. Here, we systematically study amphiphilic polyoxyethylene sorbitan monooleate, oleylamine, sorbitan monooleate, and oleamide to modify SiO2 through simple hydrogen‐bonded self‐assembly in order to replace the traditional silane coupling agent with low modification efficiency, many side reactions and complex reaction process. The results show that the rolling resistance and processing energy loss of the rubber composite prepared by SiO2 modified with polyoxyethylene sorbitan monooleate and oleylamine are significantly reduced, and other physical and mechanical properties (tensile strength, tear strength, and wear resistance) are also significantly improved compared with the silane coupling agent commonly used in green tire tread. Meanwhile, carbon–carbon double bonds belonging to polyoxyethylene sorbitan monooleate and oleylamine can participate in vulcanization of rubber to strongly improve the dispersion ability of SiO2 and the interface interaction between SiO2 and rubber matrix, so as to develop the fuel‐efficient green tire tread with high performance and low rolling resistance.

Treatment of natural rubber with bio-based components: A green endeavor to diminish the silica agglomeration for tyre tread application

Production of green tyres by replacing carbon black (CB) with silica in natural rubber (NR) has gathered attention in automotive industries in the recent past. Incorporating high dosages of silica in NR by solid-state mixing is a huge challenge. In green tyre technology, abrasion resistance index (ARI) is crucial alongside rolling resistance, wet grip, and heat build-up. In this study, two new non-silane coupling agents have been introduced to replace bis(3-Triethoxysilylpropyl)disulfide (TESPD). Amidst them, chemical-A (sorbitol) as an alternate coupling agent of TESPD effectively achieved most properties except ARI. Hence, the naturally obtainable sustainable and cost effective chemicals A and B (B-sorbic acid) are incorporated during mastication, acting as blocking agents. Consequently, chemical-A as a blocking agent executed remarkable improvement in crucial properties, including ARI. Furthermore, the optimization study of sorbitol is accomplished based on curing time, FTIR, and XPS analysis. Subsequently, using similar quantity (0.5 phr) sorbitol in silica-CB filled NR compound evidenced better performances as tyre tread compound.

Methodological Characterization of Rubber–Filler Interactions in Silica‐Filled SBR/BR Systems

AbstractSince some decades, styrene–butadiene rubber (SBR) and butadiene rubber (BR) polymers have been used to prepare silica‐filled raw mixtures basing on SBR/BR binary blends for green tire technology. Utilization of high filler concentrations and various components in these complex reinforced rubber systems make the analysis of rubber–filler interactions difficult. Developing new characterization methods and carrying out some methodological characterizations are important for the material and property investigations in this field. In this study, direct and indirect characterization methods mostly used for investigations of rubber–filler and filler–filler interactions, their potential relationships to each other and the problems of characterization methods especially imaging techniques at micro and nanoscale, are discussed for silica‐filled SBR and BR systems.

Investigating the potential of sustainable use of green silica in the green tire industry: a review.

Undoubtedly, with the increasing emission of greenhouse gases and non-biodegradable wastes as the consequence of over energy and material consumption, the demands for environmentally friendly products are of significant importance. Green tires, a superb alternative to traditional tires, could play a substantial part in environmental protection owing to lower toxic and harmful substances in their construction and their higher decomposition rate. Furthermore, manufacturing green tires using green silica as reinforcement has a high capacity to save energy and reduce carbon dioxide emissions, pollution, and raw material consumption. Nevertheless, their production costs are expensive in comparison with conventional tires. In this review article, by studying green tires, the improvement of silica-rubber mixing, as well as the production of green silica from agricultural wastes, were investigated. Not only does the consumption of agricultural wastes save resources considerably, but it also could eventually lead to the reduction of silica production expenses. The cost of producing green silica is about 50% lower than producing conventional silica, and since it weighs about 17% of green silica tires, it can reduce the cost of producing green rubber. Accordingly, we claim that green silica has provided acceptable properties of silica in tires. Apart from the technical aspect, environmental and economic challenges are also discussed, which can ultimately be seen as a promising prospect for the use of green silica in the green tire industry.

Reducing dynamic heat build‐up of styrene butadiene rubber/carbon black by filling aramid pulp coated with natural rubber latex

AbstractThe manufacture of green tires with low heat build‐up has attracted extensive attention. Furthermore, the trouble to solve the problem of rubber failure caused by tires dynamic heat build‐up is a great challenge faced by the automotive tire industry. In this article, a method of preparing styrene butadiene rubber/carbon black/aramid pulp‐natural rubber latex (SBR/CB/AP‐NRL) composites was described in detail, which used AP coated with NRL to fill SBR/CB. A flexible interface layer was constructed between fibers and rubber matrix, making for forming a large specific surface area of the NRL. The mechanism of reducing heat build‐up of the rubber composite through “deforming transformation” in the flexible interface layer was discussed. In addition, the NRL interface layer contributed to the dispersion of the AP in the rubber matrix and the good interfacial bonding between AP and the rubber matrix. In the experiment of replacing a part of CB with a certain content of AP‐NRL, it was found that the temperature rise of the rubber composites decreased by 8.33% with 1 phr modified AP replacing 5 phr CB. The strategy of reducing dynamic heat build‐up of rubber composite provides a new idea for the development of green tire.

Enhanced mechanical properties and interfacial interaction of ESBR composites by introducing silica decorated with epoxy functionalized elastomer

An epoxy functionalized elastomer (ethylene-vinyl acetate-glycidyl methacrylate terpolymer) (EVMG) was used as macromolecular modifier to prepare SiO2@EVMG organic hybrid materials modified with SiO2. The self-polymerization of dopamine on the surface of in-situ generated SiO2 forms a polydopamine (PDA) layer, which provides a reaction platform to prepare organic hybrid materials. During the preparation of SiO2@EVMG organic hybrid materials, a ring-opening reaction takes place between the amine group and catechol of the PDA and the epoxy groups of EVMG via covalent bonding interfaces between SiO2-PDA and EVMG. ESBR/SiO2@EVMG composites were prepared without silane coupling agent. The incorporation of grafted epoxy functionalized elastomer EVMG on the surface of SiO2 resulted an improvement of the dispersion of SiO2 and the interfacial interaction between SiO2 and ESBR, which were analyzed and verified in detail by dynamic mechanical analysis (DMA) and rubber process analyzer (RPA). It has been observed that the tensile strength, wear resistance and the wet skid resistance are increased by 63.1%, 30% and 26.5%, respectively when compared with ESBR/SiO2 composites, this provides an unique idea for the preparing high performance green tires.

Improved mechanical, thermal conductivity and low heat build-up properties of natural rubber composites with nano-sulfur modified graphene oxide/silicon carbide

It is still a bottleneck to simultaneously attain enhanced mechanical properties, thermal conductivity and low heat build-up properties for graphene-rubber composites obtained by conventional fabrication processes. The critical elements to enhance the comprehensive performance of rubber include excellent dispersion and the interaction of filler and matrix. In this work, the increased filler structure degree with point-surface structured SiC/GO (SG) and the strong interface modified with nano-sulfur synergistically improve the dispersibility and interfacial interaction, which effectively achieves excellent integrated performance at low filler content. More importantly, nano-sulfur not only acts as a modifier to improve interfacial compatibility, but also has a vulcanization function that enables SG and natural rubber (NR) molecular chains to form a uniformly distributed cross-linked network structure. Consequently, only when 4 phr of SiC/GO-S (SG-S) filler was added to NR, the tensile strength, thermal conductivity and low heat generation properties are higher than those of NR/GO rubber by 22.5%, 21.2% and 8.3%. Therefore, this work may open new horizons for the development of green tire.

A novel VOC free bio-based coupling agent and its using strategy facing green tires with excellent dynamic performances

For reducing volatile organic compounds (VOCs) emission in the preparation of “green tires” with ideal dynamic properties, Sulfurized Cardanol Polyoxyethylene Ether (SCPE), a VOC free bio-based coupling agent was designed and synthesized by using natural plant extracts as the main raw material. The structure of SCPE was confirmed by FT-IR, 1H NMR, Raman, GPC, DSC and XRD. XPS, FT-IR and TGA analyses demonstrated that the existence of chemical bonding and hydrogen bonding between SCPE and silica. The co-vulcanization of the SCPE and rubber matrix was proved by DSC and oscillating disc rheometer. The gas chromatography-mass spectrometry substantiated that there is no ethanol (a kind of VOCs) emission from the reaction of SCPE and silica. Then the silica/solution styrene-butadiene rubber (SSBR) nanocomposites prepared by using SCPE and bis(3-triethoxysilylpropyl)-tetrasulfide (TESPT) were studied and compared with the silica/SSBR nanocomposite without coupling agent for confirming the reducing filler network and coupling interaction. Moreover, the effects of SCPE on dynamic and static mechanical properties of silica/SSBR nanocomposites were investigated, which demonstrated that using the mixture of SCPE and TESPT was a favorable strategy for “green tires” with lower energy loss, better wet-skid resistance and mechanical properties on the premise of reducing VOC emission.

Preparation of Styrene-Butadiene Rubber (SBR) Composite Incorporated with Collagen-Functionalized Graphene Oxide for Green Tire Application.

Styrene-butadiene rubber (SBR) is a synthetic polymer primarily used in the tire industry, due to its good collaborative properties with additives and fillers. In the present work, we aim to synthesize an SBR composite reinforced with graphene oxide filler to be made biodegradable. In composite preparation, we fabricated styrene-butadiene rubber/graphene oxide/collagen (SBR/GO/COL) composites by adding a biodegradable biomolecule of elastin collagen fillers at 1.5 wt% and 2.5 wt%. Those prepared SBR/GO/COL composites, along with pure SBR and SBR/GO as control samples, were characterized using advanced analysis techniques, and their biodegradability was also evaluated. From microscopy examination results, the morphology of pure SBR had been improved after the addition of GO for SBR/GO composite by revealing a compact structure with a smoother surface. As for the SBR/GO/1.5COL sample, the 1.5 wt% COL filler was found to be effectively embedded in the SBR/GO matrix. However, the 2.5 wt% COL amount led to the formation of an aggregated structure in the SBR/GO/2.5COL sample due to the unreacted interface between COL filler and SBR/GO. The porosity had also been improved for SBR/GO/1.5COL sample, imparting it with a surface area suitable for tires in the automobile industry. From elemental analysis, the presence of nitrogen was detected for the collagen-filled SBR composite, proving the successful incorporation of collagen fibrils. The physicochemical analysis also detected a trace of graphene oxide and collagen functional groups in the SBR composite. In addition, the thermal analysis revealed those collagen-filled composites had stable heat tolerance behavior, which is suitably used in extreme weather conditions. Moreover, the SBR/GO/1.5COL sample exhibited good characteristics in both mechanical and biodegradable properties. Thus, the product of SBR/GO/1.5COL could be regarded as a promising composite for green tires in the auto industry in the future.

Preparation of silica/natural rubber masterbatch using solution compounding

There are increasing concerns about the global issues of carbon peak and carbon neutrality. The tire labeling laws about rolling resistance performance requirements have been revised accordingly. Energy-efficient “green tires,” with a lower rolling resistance, are becoming an important development direction for the tire industry. Herein, a method is proposed for preparing a silica/natural rubber (NR) masterbatch using solution compounding. The dispersion of silica in the rubber matrix was improved through the liquid-phase mixing process. Further, the loss factor (tanδ) of the rubber was reduced, ultimately reducing the rolling resistance of the material. Specifically, the modified silica slurry was prepared in cyclohexane with an interfacial modification technology, and the mixing between the silica and rubber molecular chains was completed in the organic phase. Favorable processing properties were confirmed using the Mooney viscosity test. Compared with the in situ modified silica/NR composites made using dry blending, the silica/NR composites made via solution compounding had better filler dispersion, better mechanical properties, lower tanδ and lower rolling resistance. Thus, the preparation of a silica/NR masterbatch using solution compounding provides a new procedure for the preparation of silica/NR compounds with excellent performance for “green tires.”

Self-repairable, recyclable and heat-resistant polyurethane for high-performance automobile tires

Tires are widely used in modern society and various industries. However, the formulations and manufacturing processes of traditional rubber are complex, and it is difficult to simultaneously meet requirements of low rolling resistance, high wet-skid resistance and wear resistance. Herein, we demonstrate a polyurethane elastomer material with high heat resistance and self-repairable ability to overcome the challenges encountered during the development of rubber tires. Results show that the polyurethane elastomer based on polycarbonate glycol, 1,5-naphthalene diisocyanate, and 1,4-butanediol simultaneously exhibits self-repairable ability, high heat resistance, low rolling resistance, high wear resistance, and high wet-skid resistance. The comprehensive performance of this material matches that of existing green tires. Moreover, the material can be recycled several times. This study is expected to solve the existing problems in rubber tires and provides novel ideas for preparing next-generation high-performance tire materials.

Enhancement of Green Tires Performance through Ultrasound-Assisted Mixing.

Combined with the traditional internal mixing process, a custom-built ultrasonic generator was introduced in this study. The effect of ultrasonic parameters on the comprehensive performance of tread rubber formulations was investigated. Compared to the traditional mixing process without ultrasonic wave loading, the introduction of ultrasonic enhanced the dispersion and distribution of composite particles in the rubber matrix and improved the overall performance of rubber products. The devil’s triangle relationship among the rolling resistance, wet skid resistance, and abrasion resistance of tires was improved. When the wet skid resistance was slightly lost, the rolling resistance and wear rate were effectively reduced. This study provides new insights into a strategy for optimizing the mixing process of the traditional internal mixer, reducing vehicle emissions, extending the service life of tires, and promoting the development of green tires.

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.

Efficient thermo-oxidative reclamation of green tire rubber and silanized-silica/rubber interface characterization

A stepwise separation of reclaimed silanized silica (r-SS) from waste green tire rubbers was achieved using a thermo-oxidative reclamation process, and the interfacial interaction between silanized silica and rubber was quantified. The exfoliation of the residual and bound rubber from the r-SS surfaces under different temperatures ranging from 150 to 230 ℃ was investigated, with or without the addition of vegetable oil. The particle size of r-SS decreased from hundreds of micron-meters to nanometers with the increase of reclamation degree, i.e., the degree of devulcanization of vulcanized rubber, as quantified by the sol content, and the thickness of the bound rubber layer decreased to 4–6 nm at 230 ℃. This work provides a feasible solution for recycling of waste green tires, and also promote the understanding of the interfacial interactions between silanized silica and rubber by thermo-oxidative reclamation.

A novel material based on deep eutectic solvents and its application in in‐situ modified silica‐reinforced styrene‐butadiene rubber

AbstractIn the tread compound of Green tire, silica dispersity is critical for obtaining high‐performance rubber composites. Ionic liquids have been successfully applied in improving the dispersity of silica through chemical and physical interaction. However, recent research has found that ionic liquids are harmful to the ecological environment. Meanwhile, the price of them is high. In this paper, the deep eutectic solvents (DESs‐Choline Chloride: urea) was synthesized successfully. Then it was directly introduced to prepare silica‐filled styrene‐butadiene rubber (SBR) compound via an in‐situ method. The carbonyl group and amino in DESs could constitute a hydrogen bond with the silanol on the silica surface. The hydroxyl groups were able to react with the silanol groups. The amino groups in DESs could treat as a secondary facilitator, which accelerated the curing rate. The results showed that DESs improved the dispersity of silica effectively and strengthened the interaction between silica and SBR chains. Particularly, the comprehensive performance of the rubber vulcanizates improved with an optimal ratio of bis(3‐triethoxysilypropyl)‐tetrasulfide (TESPT) to DESs being of 1:1. In addition, the DESs will serve as a novel material in silica‐filled SBR composites, which will expand its application in the tire industry.

Enhancing mechanical performance and wet‐skid resistance of emulsion styrene butadiene rubber/natural rubber latex composites via in‐situ hybridization of silanized graphene oxide and silica

AbstractThe wet skid resistance and thermal conductivity of “green tire” are the focus of research. In this work, through the use of different types of silane coupling agents, the surface of SiO2 and graphene oxide (GO) were grafted with amino and epoxy groups, respectively. The in‐situ generated SiO2 was grafted to the surface of GO by ring‐opening reaction of amino and epoxy groups. The emulsion styrene butadiene rubber/natural rubber latex (ESBR/NRL) composites were prepared by gas assisted spray flocculation process to improve the dispersion performance of hybrid filler. Because the surface of the hybrid filler contains amino and epoxy groups, it can be added as a reactive compatibilizer into the ESBR/NRL composites to improve the interface compatibility and synergistic reinforcement effect. Compared with the composites filled with SiO2, the composites filled with hybrid filler have excellent wet skid resistance and mechanical properties. When the mass ratio of GO to SiO2 is 3:10, the mechanical properties and wet skid resistance of rubber composites increase by 96.7% and 20.6%, respectively. Our preparation method of hybrid filler and flocculation process of rubber composites have broad application prospects in “green tire.”

Impacts of Green Tire Technology: Case Study of Environmental and Customer Perspectives

Contextualization: the scenario of natural resource degradation requires an urgent positioning of big companies. Government and social pressures are reflected in a company’s responsibilities and products. Research Problem: Many of a company’s required actions are focused on post-consumption, natural resource usage restrictions, and the search for alternatives to reduce the negative environmental effects. Justification: This work is concerned with improperly disposed tires, whose residues are difficult to eliminate in accordance with the National Environmental Council (CONAMA) legislation, and with the differentiation of green tires from low-cost and low-quality Chinese tires. Objectives: This research focused on the analysis of Michelin green tire technology in light of its efficiency and market views, comparing them to a common tire. Methodology: Using a case study, the cost, durability, market acceptance and associated usage benefits of both tires was studied. Results: Green tires increase fuel economy and cost slightly more than common tires. Regarding durability, the ordinary tires waste the equivalent of the value of two green tires in one life-cycle. But despite the benefits in fuel economy, reduced CO₂ emission and mileage, these benefits are usually not perceived by lay consumers. Conclusion: Green tires are a new trend, and the tests results proved that it is possible to reduce the environmental impact while maintaining or even improving comfort, safety, fuel economy and performance.

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.

New Flory‐Huggins interaction parameter between SBR and p‐phenylenediamine antioxidants and the predictive power in molecular structure and rubber formula design

AbstractThe software package was employed to calculate the three‐dimensional solubility parameters (HSP) of SBR and antioxidants. The HSP values of antioxidants are higher than SBR, meaning that the antioxidants have higher polarity compared with SBR. The solubility measurements of antioxidants in both sulfur and peroxide cured SBR vulcanizates were performed at elevated temperatures from 80 to 130°C. The maximum solubilities (∆S) of antioxidants were correlated with the temperature and also with the new Flory‐Huggins interaction parameters (χN) calculated by the HSP values. The results turn out to be that ∆S increases with increasing temperature as expected and 4020 shows higher ∆S value. Furthermore, ∆S increases with decreasing χN, and by quantitatively mathematical fitting, one functional relationship between ∆S and χN was achieved, regardless of what the crosslinking type of SBR was and what the temperature was involved. Through prediction with χN, one can get that SBR grades with higher styrene content and butadiene/vinyl ratio result in lower χN and accordingly better compatibility with N3100. One of the possible applications of χN is to select suitable SBR and antioxidant structures to design the ever‐increasing SBR‐based green tire tread formula.