Polybutadiene rubbers with urethane linkages prepared by a dynamic covalent approach for tire applications

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.

Biochar from waste agriculture as reinforcement filer for styrene/butadiene rubber

Carbon black (CB), obtained by incomplete combustion of heavy petroleum products, is the most important filler used to improve the properties of various rubber composites. Its production process causes very serious environmental impacts in addition to its dependence on nonrenewable resources. Therefore, the trend has been to use eco‐friendly alternative materials that reduce the pollution associated with the CB production process and at the same time achieve the required mechanical properties of rubber composites. Biochar, a carbon‐rich solid product, could fulfill this role. It can be obtained by pyrolysis of organic matter such as agricultural waste in the absence of air at temperatures of 400–600°C. Herein, biochar was used in different ratios with CB to investigate its effect on the mechanical properties of styrene/butadiene rubber. The chemical composition of biochar and CB was investigated using a scanning electron microscopy and X‐ray fluorescence. In addition, the thermal properties, tensile strength, elongation at break, as well as thermo‐oxidative aging of the prepared rubber were studied. The tensile strength for styrene/butadiene rubber (SBR) composites containing 100% CB was 14.9 MPa, which decreases by adding biochar where it becomes 13.5, 11.2, 9.5, and 6.9 for SBR composites containing 25%, 50%, 75%, and 100% biochar, respectively. Furthermore, the vulcanized sample with 25% biochar (E2) shows higher retained tensile strength values than that containing 100% CB (E1) with increasing the aging time.

Tandem metathesis depolymerization and cyclopolymerization toward flexible-rigid block copolymer with unique damping properties

Metathesis depolymerization (MDP) of natural rubber (NR) was readily conducted to afford depolymerized NR (dNRx) bearing the living chain end, which can initiate metathesis cyclopolymerization (MCP) of 1,6-heptadiyne monomers to...

LIQUID POLYBUTADIENE EXTENDED ESBR/SILICA WET-MASTERBATCH COMPOSITES FOR IMPROVING ABRASION RESISTANCE AND DYNAMIC PROPERTIES OF TIRE TREAD COMPOUNDS

Silica wet-masterbatch (WMB) is a well-known technique for manufacturing high-content, highly dispersed silica-filled compounds. Emulsion styrene–butadiene rubber (ESBR)/silica WMB offers several advantages, including excellent silica dispersion and reduced hysteresis, as compared with conventional dry masterbatch (DMB) compound. However, because of the residual emulsifiers in ESBR latex, it can exhibit a decrease in the crosslink density and reductions in its mechanical properties. Moreover, the abrasion resistance cannot be significantly enhanced because of the tradeoff between the improvement in silica dispersion and decrease in crosslink density. Accordingly, the objective of this study was to improve the silica dispersion and abrasion resistance of ESBR/silica WMB compounds by using liquid polybutadiene rubber (LqBR) extended WMB. In detail, three types of LqBR were emulsified to LqBR emulsions, and three types of LqBR extended WMBs were produced by co-coagulating ESBR latex, silane-modified silica, and the LqBR emulsion. A thorough characterization was conducted with emphasis on the silica content, cure characteristics, mechanical properties, abrasion resistance, and dynamic viscoelastic properties. Based on the results, silane-terminated LqBR extended WMB vulcanizate showed a 58% improvement in the 300% modulus, 48% reduced DIN abrasion loss, and a 23% improvement in dynamic properties.

Isolated-alkene-linked porous organic polymers (BIT-POPs): facile synthesis via ROMP and distinguishing overlapping signals in solid-state 13C NMR

The chemical structures of novel isolated-alkene-linked porous organic polymers (named BIT-POPs) were investigated through spectral editing techniques based on solid-state NMR.

Facile synthesis of norbornene–ethylene–vinyl acetate/vinyl alcohol multiblock copolymers by the olefin cross-metathesis of polynorbornene with poly(5-acetoxy-1-octenylene)

New norbornene−ethylene–vinyl acetate/vinyl alcohol multiblock copolymers are synthesized via the olefin cross-metathesis reaction of polynorbornene with poly(5-acetoxy-1-octenylene) followed by CC bond hydrogenation and acetoxy group deprotection.