Wet Skid Resistance Research Articles

Influence of high cis-1,4-liquid polydienes on properties of carbon-black filled composites

High cis-1,4 liquid polybutadiene (cLBR) and polyisoprene (cLIR) with narrow molecular weight distribution were prepared by the chain-transfer coordination polymerization. The effects of cLBR and cLIR on the physical and dynamic mechanical properties of carbon-black filled composites containing single polybutadiene (PBR) or a blend of PBR/polyisoprene (PIR), were investigated. The results showed that cLBR and cLIR effectively ameliorated filler dispersion compared with the treated distillate aromatic extract (TDAE) oil. The wet skid resistance and rolling resistance of vulcanized PBR/PIR composites plasticized with 5 phr cis-1,4 liquid rubbers were significantly improved. Therefore, a new type of plasticizers cLBR and cLIR that are environmental benign and highly compatible with matrix rubbers, has been discovered to replace the conventional TDAE oil used in fabricating the “green” tyres.

Synergistic enhancement of magic triangle properties of PC tread stocks modified by amine-capped trans-1,4-poly (butadiene-co-isoprene)

The development of high-performance “green tires” with synergistically improved “magic triangle” properties like lower rolling resistance, higher wet-skid resistance and higher abrasion resistance has always been a hot issue. In this work, an effective strategy for developing high-performance “green tires” with simultaneously improved “magic triangle” properties of solution-polymerized styrene-butadiene rubber (SSBR)/cis-1,4-polybutadiene rubber (BR) nanocomposites modified by amine-capped trans-1,4-poly(butadiene-co-isoprene) copolymers (F-TBIR) was proposed. A series of F-TBIR with 10–60 mol% amine-capped efficiency (CE) and 30-90 × 104 weight-average molecular weight (Mw) were synthesized by using heterogeneous TiCl4/MgCl2–Al(i-Bu)3 Ziegler-Natta catalyst with dicyclohexylamine (DCHA) as chain transfer agent (CTA). With the increase in CE of F-TBIR, the silica-filled SSBR/BR/F-TBIR compounds exhibited improved green strength, modulus at 100 % elongation and bound rubber, and their vulcanizates showed synergistically improved “magic triangle” properties like obviously reduced rolling resistance and abrasion loss, and increased wet-skid resistance. It was found that the incorporation of 10 phr F-TBIR3 with CE of 60 mol% and Mw of 32 × 104 resulted in highly expected properties of the SSBR/BR/F-TBIR3 nanocomposite. The contribution mechanism of F-TBIR3 was discussed based on the improvements of polymer network structures and filler network structures. This work is expected to provide an effective strategy to construct the desired network structures for high-performance rubber composites.

Raw rubber network of acid-free natural rubber and its application with solution-polymerized styrene butadiene rubber in green tires

Natural raw rubber was prepared by flash evaporation process (VNR), its raw rubber network was compared with that of acid-coagulated rubber (STR20), and the effects of the ratios of VNR and STR20 to SSBR on the comprehensive performance of green tire composites were investigated. The results showed that compared with 80SSBR composites, the tensile strength and tensile product coefficient of 80VNR composites were improved by 23 % and 94 %, and the Payne effect, compression heat generation, and rolling resistance were reduced by 39 %, 9 %, and 5 %, respectively. Compared with 40STR20/40SSBR composites, the tensile product coefficient, wear resistance, and wet skid resistance of 40VNR/40SSBR composites are increased by 11 %, 5 %, and 5 %, respectively, and the Payne effect, compression heat generation, and rolling resistance were reduced by 46 %, 11 %, and 5 %, respectively. This study increased the amount of natural rubber in the green tire formulations, improving the performance of composites while achieving sustainability.

Hybrid Carbon Black/Silica Reinforcing System for High-Performance Green Tread Rubber.

Silica, as a high-quality reinforcing filler, can satisfy the requirements of high-performance green tread rubber with high wet-skid resistance, low rolling resistance, and low heat generation. However, the silica surface contains abundant silicon hydroxyl groups, resulting in a severe aggregation of silica particles in non-polar rubber matrix. Herein, we explored a carbon black (CB)/silica hybrid reinforcing strategy to prepare epoxidized natural rubber (ENR)-based vulcanizates. Benefiting from the reaction and interaction between the epoxy groups on ENR chains and the silicon hydroxyl groups on silica surfaces, the dispersion uniformity of silica in the ENR matrix was significantly enhanced. Meanwhile, the silica can facilitate the dispersity and reinforcing effect of CB particles in the ENR matrix. By optimizing the CB/silica blending ratios, we realized high-performance ENR vulcanizates with simultaneously improved mechanical strength, wear resistance, resilience, anti-aging, and damping properties, as well as reduced heat generation and rolling resistance. For example, compared with ENR vulcanizates with only CB fillers, those with CB/silica hybrid fillers showed ~10% increase in tensile strength, ~20% increase in elongation at break, and ~20% increase in tensile retention rate. These results indicated that the ENR compounds reinforced with CB/silica hybrid fillers are a promising candidate for high-performance green tread rubber materials.

Novel Design of Eco-Friendly High-Performance Thermoplastic Elastomer Based on Polyurethane and Ground Tire Rubber toward Upcycling of Waste Tires.

Waste rubber tires are an area of global concern in relation to reducing the consumption of petrochemical products and environmental pollution. Herein, eco-friendly high-performance thermoplastic polyurethane (PU) elastomers were successfully in-situ synthesized through the incorporation of ground tire rubber (GTR). The excellent wet-skid resistance of PU/GTR elastomer was achieved by using mixed polycaprolactone polyols with Mn = 1000 g/mol (PCL-1K) and PCL-2K as soft segments. More importantly, an efficient solution to balance the contradiction between dynamic heat build-up and wet-skid resistance in PU/GTR elastomers was that low heat build-up was realized through the limited friction between PU molecular chains, which was achieved with the help of the network structure formed from GTR particles uniformly distributed in the PU matrix. Impressively, the tanδ at 60 °C and the DIN abrasion volume (Δrel) of the optimal PU/GTR elastomer with 59.5% of PCL-1K and 5.0% of GTR were 0.03 and 38.5 mm3, respectively, which are significantly lower than the 0.12 and 158.32 mm3 for pure PU elastomer, indicating that the PU/GTR elastomer possesses extremely low rolling resistance and excellent wear resistance. Meanwhile, the tanδ at 0 °C of the above-mentioned PU/GTR elastomer was 0.92, which is higher than the 0.80 of pure PU elastomer, evidencing the high wet-skid resistance. To some extent, the as-prepared PU/GTR elastomer has effectively solved the "magic triangle" problem in the tire industry. Moreover, this novel research will be expected to make contributions in the upcycling of waste tires.

Predicting glass transition temperature of polymers by combining molecular dynamics simulations and machine learning techniques

Polymeric materials, valued for their cost-effectiveness and ease of processing, play a pivotal role in diverse applications. Among them, solution polymerized styrene butadiene rubber (SSBR) stands out with low rolling and wet skid resistance, ideal for eco-friendly tire. The glass transition temperature (Tg) is an important parameter in determining the performance of SSBR, which is time-consuming to test with conventional experiments. In recent years, machine learning (ML) has emerged as a useful tool in materials science. In this study, all-atom molecular dynamics (AAMD) simulation provided the foundational training data. Subsequently, ML techniques are utilized to efficiently predict SSBR’s Tg based on its content of four key structural components. To address the challenge of limited sample sizes, the innovative integration of Ordinary Kriging (OK) from geostatistics and Nearest Neighbor Interpolation (NNI) was employed to compute label values for interpolation points, which surpasses previous studies relying solely on NNI. Comparative analysis of four ML models (XGBoost, Ridge, LASSO, and SVR) reveals XGBoost’s superior performance in handling this nonlinear problem, with consistently high R2 and low RMSE scores. Through 900 repeated experiments, the model demonstrates robustness, maintaining an average R2 of approximately 0.9703. Ultimately, the novel integrated ML approach (NNI-OK-XGBoost) was proposed. Furthermore, four new combinations of structural unit content were evaluated using both ML predictions and AAMD simulations. The validation confirms the efficiency and accuracy of this method in predicting SSBR’s Tg across varying composition ratios within a specified composition space. This work presents a viable solution for accurately and rapidly predicting the Tg of polymeric materials, particularly in scenarios with limited sample sizes.

Improved wet skid resistance of NR/SBR composites induced by irradiation vulcanised styrene-butadiene rubber particles

Improving the wet skid resistance of tire tread is very important for the safety of vehicle driving. Using a novel ultrafine full-vulcanised powdered styrene-butadiene rubber (UFPSBR), this work prepared an advanced UFPSBR/nature rubber (NR)/styrene-butadiene rubber (SBR) composites used for the tire tread. On one hand, the UFPSBR improves the loss factor (tanδ) values of the UFPSBR/NR/SBR composites in temperature range from 0 °C to 10 °C, indicating that the UFPSBR modified tire tread has better wet skid resistance. On the other hand, the UFPSBR increases the surface roughness and complex modulus of the UFPSBR/NR/SBR composites while decreasing the water contact angle of the UFPSBR/NR/SBR composites, which is conducive to increasing the wet skid resistance of tire tread by puncturing the water film or leading a thinner water film between tire tread surface and road surface. Above researches are more comprehensive and benefit for studying the advanced green tire with high wet skid resistance.

Natural coal-derived graphite as rubber filler and the influence of its progressive graphitization on reinforcement performance

This study introduces a reinforcing rubber filler, natural coal-derived graphite (NCDG), evaluating how its progressive structural evolution from meta-anthracite (MA), semi-graphite (SG) to cryptocrystalline graphite (CG) during the natural graphitization process affects their reinforcing performance to styrene-butadiene rubber (SBR) composites. The highly graphitized NCDG fillers exhibit good filler dispersion, more bound rubber content, and well compatibility between filler and rubber matrix when compounded with SBR, and significantly enhance the mechanical properties of SBR composite (tensile strength can reach 22.8 MPa), as well as improving the storage modulus, wet-skid resistance, wear resistance, and electrical conductivity. The formation of microcrystalline multilayer graphene and graphene nanoplatelets exfoliated by mechanical shear stress during ball grinding and rubber compound mixing plays an important role in improving the reinforcement performance of rubber composites. This research provides valuable insights into the utilization of NCDG as a cost-effective and environment-friendly reinforcing filler for rubber composites.

Tire tread rubber compound with high wet skid resistance and low rolling resistance

AbstractThe preparation of four types of epoxidized iron‐based comb butadiene‐isoprene rubber (EBIR) with different epoxidation degrees (4.7%, 6.4%, 10.2%, and 12.3%) was investigated for the first time in this study. The modification involved the use of hydrogen peroxide and formic acid as raw materials for the epoxidation process. Following this, silica/EBIR composites were prepared by mixing EBIR with silica nanoparticles, without the use of a silane coupling agent (SCA). The objective was to investigate the influence of the epoxidation degree on the structure and properties of the resulting silica/EBIR nanocomposites. The results indicated that the introduction of epoxy groups had a positive effect on the interfacial interaction between the rubber and filler, leading to improved dispersion of the silica nanoparticles in the rubber matrix. Consequently, the tensile properties, wet skid resistance, and abrasion resistance of the silica/EBIR composites were found to be superior to those of the un‐epoxidized silica/BIR composites. Furthermore, comparing the silica/EBIR‐12.3 nanocomposites with silica/BIR‐Si69 nanocomposites, it was revealed that silica/EBIR‐12.3 showed a 69.4% enhancement in wet skid resistance and an 8.0% reduction in rolling resistance. These findings demonstrate the potential of silica/EBIR composites for high‐performance tire tread rubber applications, offering environmental benefits and improved properties.

Structure and performance of silica/functionalized solution-polymerized styrene butadiene rubber/epoxidized butadiene rubber nanocomposites

Functionalized solution-polymerized styrene butadiene rubber (FSSBR) is extensively used in “green tires” tread, so it is very important to improve the phase distribution of silica in FSSBR blends. In this work, the butadiene rubber (BR) is epoxidized (EBR) and blended with FSSBR. The effect of epoxidation degree on the structure and performance of the silica in combination with bis-(γ-triethoxysilylpropyl) disulfide (TESPD) filled FSSBR/EBR nanocomposites (S/FSSBR/EBR) is investigated. S/FSSBR/EBR3 nanocomposite with epoxidation degree of 3% achieves the best dispersion and phase distribution of silica by ring-opening reaction between epoxy group of EBR and silanol group of silica. Compared with silica in combination with TESPD filled FSSBR/BR nanocomposite (S/FSSBR/BR), S/FSSBR/EBR3 has better abrasion resistance, 13% improvement in wet-skid resistance and 15% reduction in rolling resistance, which provides an excellent solution for the preparation of high-performance “green tires".

Balancing the "magic triangle" performance of tire rubber nanocomposites with novel low VOC silane coupling agents

Nowadays, coupling agents are still the core technology of the “green tire” industry, which not only effectively weaken the silica network but also enhance the interface interaction between silica and rubber matrix. However, the reaction between the traditional silane coupling agents and the silanol groups on silica surface generates a large amount of volatile organic compounds (VOCs), which can affect the performance of the rubber composites and pollute the environment. In this paper, a series of novel coupling agents with low VOC emission were synthesized by reacting fatty alcohol polyoxyethylene ethers of different polyether lengths (AEOX) with bis-[γ-(triethoxysilyl) propyl]-tetrasulfide TESPT (Si69). The structure of the novel coupling agent was characterized using FT-IR and 1H NMR. Meanwhile, it has been proven through FT-IR, XPS, TGA, and GCMS that the novel coupling agent can react with silica and reduce VOC emissions. Then the novel coupling agent was added into the silica/natural rubber (NR) nanocomposite. The test results of rubber composites showed that the addition of novel coupling agent can significantly enhance the dispersion of silica in the rubber matrix and effectively balance the "magic triangle" performance of tire. As a result, the rolling resistance of the silica/NR composites is reduced by 15.8 %, the wet skid resistance is improved by 14.2 %, and the abrasion resistance is improved by 20.3 %.

Enhancing mechanical, self-healing and damping properties of dual-modified Eucommia ulmoides gum by introducing epoxy and perfluoroalkyl groups

Eucommia ulmoides gum (EUG) is a bio-based polymer with the structure of trans-1,4-polyisoprene, and easy to crystallize at room temperature, which limits its application in rubbery materials. The epoxidized EUG (E26EUG) with an epoxidation degree of 26% was readily prepared and further grafted with different contents of polar perfluoroalkyl groups by ring-opening reaction of epoxy group on the E26EUG backbone using perfluorocarboxylic acid as the nucleophilic reagent under mild conditions, affording the modified elastomers Em-xEUG-Fx with enhanced mechanical properties, good self-healing performance, and improved damping properties. The vulcanized elastomers VE26EUG and VEm-xEUG-Fx also exhibited excellent mechanical and damping properties. In addition, a high damping loss value at 0 °C in dynamic mechanical spectra indicated a good wet-skid resistance of the modified EUG elastomers before and after vulcanization. This research is of great significance for extending the applications of functional EUG rubbery materials.

Establishing a Production Facility for the Extraction and Processing of Jackfruit-Based Latex Artocarpus Heterophyllus as an Integration into Aviation Sealants

Abstract The feasibility study aimed to create a manufacturing facility for the production of the Skyjack sealant, a sealant with the jackfruit-based latex as its main component. It is used to cover gaps in order to prevent fluids from entering, and also serves as a protection by using it as a coating. Skyjack company’s main goal is to develop an affordable sealant that will meet the criteria of needs of the aviation industry for aircraft manufacturing and maintenance. This project will be able to add to the supply of affordable and high-quality sealants nationally and internationally, maximize local resources, and create employment. Along with a few other chemical elements, jackfruit latex contains both cis-1,4 polyisoprene and trans-1,4 polyisoprene. Since Artocarpus heterophyllus' polymer chains are substantially shorter than those of Hevea brasiliensis', it cannot serve as a substitute for natural rubber, which is the most widely used rubber. As a result, jackfruit latex cannot be utilized to replace natural rubber (NR), but it can be used as a low molecular weight natural resin, particularly to enhance tires' wet skid resistance (WSR) and to better disperse carbon black in rubber compositions. Keywords: Artocarpus heterophyllus, aviation, sealant, natural rubber

Role of Terminal Groups of cis-1,4-Polyisoprene Chains in the Formation of Physical Junction Points in Natural Rubber.

The terminal structures of cis-1,4-polyisoprene (PI) chains play a vital role in the excellent comprehensive performance of Hevea natural rubber (NR) with properties such as high toughness, tear-resistance, and wet skid resistance. The cis-1,4-polyisoprene chain constituting NR exhibits a distinct composition of terminal groups comprising two distinct types, namely, the ω and α terminal groups. The structures of the ω terminal [dimethyl allyl (DMA)-(trans-1,4-isoprene)2] and six kinds of α end groups of the polymer chain of NR have been explored by utilizing a newly developed 2D NMR method. In the present work, we examine different kinds of PI melt systems, and we choose various combinations of terminal groups: Hydrogen, one DMA unit with two trans isoprene units as ω end groups and ester-terminated isopentene (α1), hydroxy-terminated isopentene (α2), ester-terminated isobutane (α3), hydroxy-terminated isobutane (α4), ester-terminated 1,4-cis-isoprene (α5), and hydroxy-terminated 1,4-cis-isoprene (α6), i.e., HPIH (PI0)-pure PI (Hydrogen terminal), ωPIα1 (PII), ωPIα2 (PIII), ωPIα3 (PIIII), ωPIα4 (PIIV), ωPIα5 (PIV), and ωPIα6 (PIVI). We evaluated dynamic and static properties of PI chains such as the end-to-end vector autocorrelation function (C(t)), its average relaxation time (τ), end-to-end distance (Ree), and radius of gyration (Rg). We also estimated the diffusion coefficients of polyisoprene chains and pair correlation functions [radial distribution functions (RDFs)], potentials of mean force (PMFs) in between end residues, and survival probability (P(τ)) of end groups around the end group by analyzing the equilibrated trajectories of full-atom MD simulations. As per the examination of C(t), rotational relaxation time τ, and RDFs, we discovered that the existence of a strong hydrogen bond in α2-α2, α4-α4, and α6-α6 residues makes the dynamics of hydroxy-terminated polyisoprene chains in ωPIα2,α4,α6 melt systems slower. From the analyses of RDFs and PMFs (W(r)), the association between [α2]-[α2], [α4]-[α4], and [α6]-[α6] terminals in ωPIα2,α4,α6 melt systems is significantly stronger than in [ISO]-[ISO] [Hydrogen terminated 1,4-cis-isoprene:(ISO)] in HPIH and ω-ω, [α1]-[α1], [α3]-[α3], and [α5]-[α5] in ωPIα1,α3,α5 systems. We quantified the fraction of cluster formation of terminal groups of a given size in the seven PI melt systems by employing the criteria of PMFs. It is revealed that no stable cluster exists in the HPIH, ωPIα1, ωPIα3, and ωPIα5 melt systems. Conversely, in the ωPIα2, ωPIα4, and ωPIα6 systems, we perceived stable clusters of [(α2)p] [(α4)p] and [(α6)p] end groups where p (2 ≤ x ≤ 6). These stable clusters validate the presence of physical junction points in between hydroxy-terminated polyisoprene chains through their α2, α4, and α6 terminals. These physical junction points might be crucial for superior properties of NR such as high toughness, crack growth resistance, and strain-induced crystallization.

Novel butadiene/isoprene copolymer with predominant 1,2/3,4-units: A tough thermoplastic elastomer material with superior dynamic mechanical properties

The synthesis of 1,2/3,4-regulated BD/IP copolymers has been of importance due to its fascinating properties. In this study, we successfully synthesized such copolymers using an iron-based catalyst with high activity. The contents of BD/IP unit in the resulting PBIs were closely consistent with the [BD]/[IP] feeding ratios, allowing for modulation of the composition and properties of the PBIs. These novel elastic materials exhibit superior and adjustable mechanical properties, as well as excellent dynamic mechanical properties, making them promising for high-performance rubber materials. In particular, these materials have the potential to address the “devil triangle” of tires by simultaneously increasing wet-skid resistance and decreasing rolling resistance.

Silica reinforced epoxidized solution-polymerized styrene butadiene rubber and epoxidized polybutadiene rubber nanocomposite as green tire tread

Solution-polymerized styrene butadiene rubber (SSBR) and high cis-polybutadiene rubber (BR) are usually used as matrix and silane coupling agent (SCA) modified silica as the filler in the conventional green tire tread. However, the SCA cannot achieve uniform distribution of silica, moreover the modification process generates volatile organic compounds. In this work, a novel silica reinforced epoxidized SSBR(ESSBR)/epoxidized BR (EBR) nanocomposite (S-ESSBR/EBR) without SCA is prepared. The ESSBR and EBR with different epoxidation degree are synthesized by an oxidant H2O2 and reaction-controlled phase-transfer catalyst CPC-PW4O16. The microstructure and performance of S-ESSBR/EBR nanocomposites are investigated and compared with the silica reinforced SSBR/BR nanocomposite (S-SSBR/BR-Si75) using Si75 as SCA. Silica nanoparticles transfer from ESSBR phase to EBR phase with increasing epoxidation degree of EBR, so the distribution of silica in two phases becomes homogeneous. The S-ESSBR/EBR nanocomposite exhibits high wet skid resistance, low rolling resistance and excellent abrasion resistance as green tire tread.

Toward Biosourced Elastomer from β-Farnesene and Styrene: Synthesis, Properties, and Mechanical Performance

Encouraged by the growing need for sustainability in the rubber industry, attempts have been made to fabricate biobased elastomers to replace existing petro-derived polymers for useful applications. Here, we demonstrate a simple and sustainable route to synthesize biobased elastomers based on β-farnesene (FA) and styrene (STY) under a high-temperature persulfate emulsion process for tire applications. The synthesized copolymer, poly(farnesene-co-styrene) (PFS), showed molecular weight (Mw) of 108 500 g/mol and 162 100 g/mol for 30 and 50 wt % styrene contents. The commoner reactivity ratios showed nonideal copolymerization behavior, as evaluated using Fineman–Ross and Kelen-Tüdös methods. The macromolecular chemical structure of PFS elastomers was confirmed by FT-IR and NMR analyses. The copolymer showed complete 1,4-cis and trans-microstructure formation. The glass-transition temperature (Tg) values of PFS elastomers were obtained in the range of −58 and −38 °C, depending on the styrene content. The PFS gum elastomers displayed improved thermal stability and single degradation pattern compared to the pristine polyfarnesene. Besides, carbon black was incorporated into the PFS elastomer matrix to prepare rubber vulcanizates for desired mechanical properties. The 50/50 FA/STY rubber vulcanizates displayed good tensile strength (4.43 MPa), elongation at break (183%). The 80/20 and 70/30 FA/STY rubber vulcanizates exhibited good wet skid resistance compared to its pristine polyfarnesene vulcanizate. This work provides an efficient approach to using emulsion polymerization for developing sustainable rubbers on an industrial scale for multifaceted applications.

Preparation of potassium oleate-kaolin/natural rubber composites by ball milling combined with gas-phase spray drying technology

In order to realize the high value-added utilization of natural clay materials in natural rubber composites, an environment-friendly animal glycerol potassium salt was introduced to modify kaolin, and the natural rubber with excellent performance were prepared by high-energy ball milling combined with gas-phase spray drying technology. The impact of the ball milling reduced the particle size and increased the specific surface area of kaolin, promoting the chemical modification of kaolin by potassium oleate. The gas-phase spray technology effectively broke the filler aggregates, and the high-temperature roller realized the instantaneous drying, reducing the oxidation and fracture of the rubber molecular chains. In this paper, the gas barrier properties, mechanical properties, anti-aging properties, dynamic mechanical properties and Payne effect of the composites were investigated. The FTIR, XPS and interfacial contact angle demonstrated the existence of a stable chemical bonding in the process of potassium oleate-modified kaolin, and the hydrophilicity of kaolin was reduced. Kaolin was uniformly and finely dispersed in the rubber matrix by spray drying technology. Compared with the traditional dry mixing, the composites prepared by the technology improved the gas barrier properties, processing properties, comprehensive mechanical properties, and the aging coefficient increased by 23.1%, and had excellent wet skid resistance and rolling resistance.

Expanding the "Magic Triangle" of Reinforced Rubber Using a Supramolecular Filler Strategy.

A strategy for optimizing the rolling resistance, wet skid and cut resistance of reinforced rubber simultaneously using a supramolecular filler is demonstrated. A β-alanine trimer-grafted Styrene Butadiene Rubber (A3-SBR) pristine polymer was designed and mechanically mixed with commercially available styrene butadiene rubber to help the dispersion of a β-alanine trimer (A3) supramolecular filler in the rubber matrix. To increase the miscibility of A3-SBR with other rubber components during mechanical mixing, the pristine polymer was saturated with ethanol before mixing. The mixture was vulcanized using a conventional rubber processing method. The morphology of the assembles of the A3 supramolecular filler in the rubber matrix was studied by Differential Scanning Calorimetry (DSC) and Transmission Electron Microscopy (TEM). The Differential Scanning Calorimetry study showed that the melting temperature of β-sheet crystals in the vulcanizates was around 179 °C and was broad. The melting temperature was similar to that of the pristine polymer, and the broad melting peak likely suggests that the size of the crystals is not uniform. The Transmission Electron Microscopy study revealed that after mixing the pristine polymer with SBR, some β-sheet crystals were rod-like with several tens of nanometers and some β-sheet crystals were particulate with low aspect ratios. Tensile testing with pre-cut specimens showed that the vulcanizate containing A3-SBR was more cut-resistant than the one that did not contain A3-SBR, especially at a large cut size. The rolling resistance and wet skid were predicted by dynamic mechanical analysis (DMA). DMA tests showed that the vulcanizates containing A3-SBR were significantly less hysteretic at 60 °C and more hysteretic at 0 °C based on loss factor. Overall, the "magic triangle" was expanded by optimizing the rolling resistance, wet-skid, and cut resistance simultaneously using a β-alanine trimer supramolecular filler. The Payne effect also became less severe after introducing the β-alanine trimer supramolecular filler into the system.

Microstructure and Performance of Green Tire Tread Based on Epoxidized Solution Polymerized Styrene Butadiene Rubber and Epoxidized Natural Rubber

Blending a solution of polymerized styrene–butadiene rubber (SSBR) with natural rubber (NR) as a matrix and silane coupling agent (SCA) modified silica as filler is widely used to prepare green tire tread. However, it is difficult to adjust the distribution of silica in different phases of a rubber blend by SCA. Moreover, the coupling reaction between silica and SCA emits volatile organic compounds. In this work, we use a new strategy to improve the distribution of silica in two phases without a SCA. Epoxidized SSBR (ESSBR) and epoxidized NR (ENR) are synthesized, and the performance of silica-filled ESSBR/ENR nanocomposite (S-ESSBR12/ENR) is investigated and compared with that of silica-filled SSBR/NR nanocomposite (S-Si75-SSBR/NR) using Si75 as the SCA. The S-ESSBR12/ENR nanocomposites have stronger interfacial interaction that results in better silica dispersion than the S-Si75-SSBR/NR nanocomposite. The epoxy groups can effectively adjust the phase selective distribution of silica. The S-ESSBR12/ENR18 nanocomposite shows homogeneous distribution, leading to the best performance. Compared with S-Si75-SSBR/NR nanocomposite, S-ESSBR12/ENR18 nanocomposite increases wet-skid resistance by 118%, reinforcing index by 38%, and abrasion resistance by 40% and decreases rolling resistance by 23%. Moreover, S-ESSBR12/ENR nanocomposites are eco-friendly and have potential application in the production of green tire treads.