Search Results (6)

Rubber tires are fundamental components of modern society and industrial operations, holding an irreplaceable position in the global manufacturing and transportation sectors. The potential for traditional rubber tires to enhance performance is gradually approaching its limits, rendering it challenging to further improve low rolling resistance, high wet-skid resistance, and high wear resistance (called “magic triangle”). Moreover, the reliance on petroleum resources for rubber hinders the sustainable development of rubber tires. In this work, a series of novel polyurethane (PU) elastomers with potential applications in high-performance automotive tires were synthesized by CO₂-based poly(propylene carbonate) diol and bio-based poly(propylene oxide) glycol (PO3G). The comprehensive influences of PO3G on the thermal, mechanical, rolling resistance, and wear properties of the elastomers were systematically investigated. The results illustrated that increasing the PO3G content significantly enhanced the wear resistance by 98.43% and the wet-skid resistance by 73.21% and reduced the rolling resistance by 15.38% of the elastomers compared to commercial green tires (HT166). The rational design strategy of PU elastomers not only effectively addresses the “magic triangle” challenge in the tire industry but leverages CO₂ to contribute to the sustainable development of the automotive sector. Full article

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. Full article

Polymerized, functionalized solution styrene–butadiene rubber (F-SSBR) is a new type of polymerized styrene–butadiene rubber solution containing specific terminal groups, which can be used in treads for high performances. However, the wet skid resistance related to safety, the rolling resistance to energy consumption, and the wear resistance to service life are often contradictory and form the performance “magic triangle”. In this work, oligomeric resins, including Coumarone resin, C₉ resin, C₅/C₉ resin and a styrene-α-methyl styrene copolymer (SSC), were used as tire functional additives and selected to replace treated distillate aromatic extract (TDAE) to improve the performances of silica-filled F-SSBR composites. The C₉ resin, C₅/C₉ resin and SSC could enhance the modulus at 300% and tensile strength of the F-SSBR composite. The four resins could improve the wet skid resistance and wear resistance of the composites. However, Coumarone resin caused poor silica dispersion in the F-SSBR matrix and eventually, the lower modulus, higher loss factor at 60 °C and the higher heat buildup in the composite were comparative to the composite with TDAE. Furthermore, the synergistic effect of the C₅/C₉ resin and SSC was found to improve the mechanical performance of the composites and it resulted in higher tensile strength and modulus, and a lower heat buildup, compared to the case when only TDAE was used. It is noted that the properties “magic triangle” was broken by the C₅/C₉ resin and SSC, and the C₅/C₉10T15 increased the wet skid resistance by 21.7%, fuel-saving rate by 2.3%, and wear resistance by 8.3%, while S20T5 increased the wet skid resistance by 30.4%, fuel-saving rate by 7%, and wear resistance by 25% compared with CG. Full article

The viscoelastic behavior and reinforcement mechanism of polyethylene glycol (PEG) as an interfacial modifier in green tire tread composites were investigated in this study. The results show a clear positive effect on overall performance, and it significantly improved all the parameters of the “magic triangle” properties, the abrasion resistance, wet grip and ice traction, as well as the tire rolling resistance, simultaneously. For the preparation of the compounds, two mixing steps were used, as PEG 4000 was added on the second stage in order to avoid the competing reaction between silica/PEG and silanization. Fourier transform infrared spectroscopy (FTIR) confirmed that PEG could cover the silanol groups on the silica surface, resulting in the shortening of cure times and facilitating an increase of productivity. At low content of PEG, the strength was enhanced by the improvement of silica dispersion and the slippage of PEG chains, which are chemically and physically adsorbed on silica surface, but the use of excess PEG uncombined with silica in the compound, i.e., 5 phr, increases the possibility to shield the disulfide bonds of bis(3-(triethoxysilyl)-propyl) tetrasulfide (TESPT), and, thus, the properties were deteriorated. A constrained polymer model was proposed to explain the constrained chains of PEG in the silica-loaded composites on the basis of these results. An optimum PEG content is necessary for moderately strong matrix–filler interaction and, hence, for the enhancement in the mechanical properties. Full article

In general, composite materials are difficult to recycle. Tires belong to this class of materials. On top, one of their main constitutents, vulcanized rubber, is as elastomer, which cannot be remolten and hence is particularly challenging to put to a new use. Today, the main end-of-life routes of tires and other rubber products are landfilling, incineration in e.g., cement plants, and grinding to a fine powder, generating huge quantities and indicating a lack of sustainable recycling of this valuable material. True feedstock recycling is not feasible for complex mixtures such as tires, but devulcanization can be done to reactivate the cross-linked polymer for material recycling in novel rubber products. Devulcanization, i.e., the breaking up of sulfur bonds by chemical, thermophysical, or biological means, is a promising route that has been investigated for more than 50 years. This review article presents an update on the state-of-the art in rubber devulcanization. The article addresses established devulcanization technologies and novel processes described in the scientific and patent literatures. On the one hand, tires have become high-tech products, where the simultaneous improvement of wet traction, rolling resistance, and abrasion resistance (the so-called “magic triangle”) is hard to achieve. On the other hand, recycling and sustainable end-of-life uses are becoming more and more important. It is expected that the public discussion of environmental impacts of thermoplastics will soon spill over to thermosets and elastomers. Therefore, the industry needs to develop and market solutions proactively. Every year, approximately 40 million tons of tires are discarded. Through the devulcanization of end-of-life tires (ELT), it is possible to produce new raw materials with good mechanical properties and a superior environmental footprint over virgin products. The devulcanization process has become an interesting technology that is able to support the circular economy concept. Full article

Current regulations demand tires with long lifetime and reduced fuel consumption without sacrificing car safety. However, tire technology still needs to reach a suitable balance between these three indicators. Here, we address them by developing a self-healing tire compound using styrene–butadiene rubber (SBR) as the matrix and reclaimed tire waste as the sustainable filler. The addition of ground tire rubber (GTR) to the matrix simultaneously improved the rolling resistance and maintained both wet grip and healing ability. We provide an in-depth analysis of the healing behavior of the material at a scale close to the relevant molecular processes through a systematic dynamic-mechanical and dielectric analysis. We found that SBR and SBR/GTR compounds show a complete recovery of stiffness and relaxation dynamics after being damaged by cyclic deformation, resulting in a heterogeneous repaired rubber network. This new development could well overcome the so-called magic triangle of tires, which is certainly one of the key objectives of the tire industry. Full article