Search Results (367)

Passenger car waste tires (PCWTs) are difficult to recycle as asphalt modifiers due to their high styrene-butadiene rubber (SBR) content and poor compatibility with asphalt. This study investigates whether hexadecylamine (HDA)-assisted thermo-mechanical devulcanization can transform PCWT rubber into an effective modifier for styrene-butadiene-styrene (SBS)-composite-modified asphalt, and how rubber dosage influences the performance balance. PCWT rubber was devulcanized using HDA-assisted twin-screw extrusion and incorporated into 90# asphalt with 3 wt% SBS at 20 wt% and 30 wt% dosages, alongside non-devulcanized PCWT and truck tire rubber for comparison. Comprehensive characterization, including sol fraction, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), and bending beam rheometer (BBR), was conducted. The results demonstrate that HDA-assisted devulcanization effectively breaks sulfur crosslinks while preserving the rubber backbone, significantly improving compatibility and low-temperature performance. Increasing the devulcanized rubber dosage from 20 wt% to 30 wt% compensates for the reduced high-temperature stiffness, achieving a balanced performance profile comparable to truck tire rubber. The novelty of this work lies in establishing HDA-assisted thermo-mechanical devulcanization as a viable pathway for converting otherwise underutilized PCWT rubber into a high-performance asphalt modifier, thereby expanding the feedstock options for crumb rubber-modified asphalt. Full article

Lost circulation of oil-based drilling fluids (OBDFs) in deep, fractured formations remains a critical challenge, primarily due to the poor retention and low pressure-bearing capacity of conventional materials on oil-wet rock surfaces. To bridge this gap, this study reports the development and field application of a novel thermo-responsive gel (SBR−g−PSA). Synthesized by grafting highly lipophilic stearyl acrylate (SA) onto a flexible styrene–butadiene rubber (SBR) backbone, the microgel exploits a UCST-like (Upper Critical Solution Temperature) phase transition behavior. At surface temperatures, rigid styrene microdomains act as physical crosslinks, maintaining the particles in a compact, highly dispersible state. Under elevated downhole temperatures (120–180 °C), these microdomains relax, triggering the massive unfolding and physical entanglement of the octadecyl side chains. This in situ topological evolution generates a resilient three-dimensional network with a high thermal degradation temperature of 346.6 °C. Rheological and macroscopic sealing evaluations demonstrate that the gel effectively adapts to OBDFs, securely sealing 1–1.5 mm fractures and limiting fluid loss to within 5 mL under a 4 MPa differential pressure. Successful field application in the deep well Dashen-X reduced severe fluid leakage from 2.42 m³/h to zero. This intelligent thermo-responsive platform offers a robust, high-performance technological solution for precise lost circulation control in deep oil and gas exploration. Full article

This study investigated the effect of the partial replacement of silica with carbon fillers, namely carbon black (CB), graphene, and carbon nanotubes (CNTs), on the curing behaviour, thermo-mechanical properties, ageing resistance, and degradation of styrene-butadiene rubber (SBR) vulcanizates. The aim was to determine whether small amounts of carbon fillers could improve the durability-related properties of silica-filled SBR compounds. Graphene and CNTs reduced the maximum curing torque compared with the CB-filled compound while maintaining satisfactory curing characteristics. Thermal conductivity increased with temperature for all materials and reached 0.126 W·m⁻¹·K⁻¹ for the graphene-filled vulcanizate at 40 °C, compared with 0.109 and 0.107 W·m⁻¹·K⁻¹ for the CNT- and CB-filled compounds, respectively. Dynamic ageing tests revealed significant differences in self-heating behaviour. After 10,000 De Mattia cycles, the graphene-filled compound exhibited the lowest temperature increase (1.5 °C), whereas the CB5/Sil15 formulation showed the highest value (4.5 °C). GC-IMS analysis confirmed the formation of volatile degradation products during cyclic ageing, while increasing carbon filler content reduced the intensity of the characteristic VOC signals. Analysis of the crosslink structure indicated that CNT-containing compounds exhibited the highest resistance to ageing-induced structural changes, whereas graphene promoted an increase in the proportion of monosulfidic and carbon–carbon crosslinks. Overall, the results demonstrate that partial replacement of silica with carbon nanofillers improves the thermo-mechanical stability of SBR vulcanizates. Graphene provided the greatest enhancement in thermal conductivity and the lowest heat build-up, while CNTs showed the highest resistance to structural changes during dynamic ageing. Full article

As a road repair material, emulsified asphalt offers advantages such as convenient construction, good fluidity, and environmental safety. However, its relatively low strength limits its application range, making performance enhancement a key research focus. In this study, waterborne epoxy resin (WER) was used to modify emulsified asphalt, and the preparation process and performance were systematically investigated. Three types of waterborne epoxy systems were selected, and through compatibility, film-forming performance, and bonding strength tests, the JT waterborne epoxy system was identified as having the best overall performance, with an optimal epoxy-to-curing-agent ratio of 1:0.6. Modified emulsified asphalts with different proportions of WER and styrene–butadiene rubber were prepared. Using fluorescence microscopy, image recognition techniques, and multiple experimental evaluations, the distribution of epoxy resin in the emulsified asphalt was quantitatively analyzed. The results show that the addition of WER significantly improves the bonding strength of emulsified asphalt, with the fastest rate of increase observed in the 5−10% range. However, a comprehensive evaluation considering microstructure uniformity, rheological performance, and water resistance indicates that the optimal overall performance is achieved in the 10−12% range, and the WER content should strictly be controlled below 15% to avoid severe local agglomeration. Meanwhile, the modified water-boiling test reveals that the adhesion between WERAE and aggregates is significantly enhanced, implying a potentially improved resistance to moisture-induced damage under practical service conditions. The standard deviation of area results indicate that when the WER content exceeds 15%, local agglomeration occurs, which is unfavorable for strength development of the modified system; the distribution uniformity results further show that when the WER content is greater than 12%, it negatively affects the uniform dispersion of WER within the emulsified asphalt. Full article

Inorganic pigments are widely used in elastomer technology primarily as coloring agents; however, the broader effects of these additives on the structure–property relationships of rubber composites remain insufficiently understood, particularly across different elastomer matrices. This study addresses this gap by systematically evaluating and comparing the effects of zirconium cerulean blue (Pigment Blue 71, PB71) and earth pigment iron ocher (IO) in natural rubber (NR), acrylonitrile–butadiene rubber (NBR), and styrene–butadiene rubber (SBR) composites. The influence of pigment loading (2–10 phr, parts per hundred parts of rubber) on rheometric behavior, crosslink density, mechanical performance, thermo-oxidative aging resistance, and combustion behavior was investigated to determine whether inorganic pigments provide benefits beyond coloration. The incorporation of pigments did not adversely affect vulcanization behavior, with the crosslink density of NR increasing from approximately 1.5 × 10⁻⁵ mol cm⁻³ for the unfilled vulcanizate to 1.5–2.3 × 10⁻⁵ mol cm⁻³ for pigment-containing composites, while SBR exhibited an increase from approximately 1.0 × 10⁻⁵ to 1.5–2.0 × 10⁻⁵ mol cm⁻³. Selected formulations also exhibited improved tensile strength and enhanced resistance to thermo-oxidative aging. Pyrolysis combustion flow calorimetry (PFCF) demonstrated that the incorporation of 10 phr IO reduced the peak heat release rate (pHRR) by approximately 11% (NR), 10% (NBR), and 3% (SBR), whereas 10 phr PB71 decreased this parameter by approximately 13%, 8%, and 38%, respectively. These findings demonstrate that inorganic pigments can serve as multifunctional colorants, simultaneously improving mechanical performance, thermo-oxidative stability, and fire resistance while maintaining effective coloration. Full article

Polymer-modified asphalt has been widely used to improve pavement durability under increasing traffic loads and complex environmental conditions. Styrene–butadiene–styrene (SBS) is one of the most effective elastomer modifiers. It can form a polymer-rich network within asphalt. Styrene–methyl methacrylate copolymer-based modifier (SMC) can be produced from recycled rubber and plastic resources. It has attracted increasing attention because of its potential compatibility, processability, and environmental benefits. This paper reviews the modification mechanisms, rheological properties, fatigue performance, aging resistance, and engineering applications of SBS-, SMC-, and SMC–SBS-modified asphalt and mixtures. Particular attention is given to the synergistic effects between SBS and SMC, including polymer swelling, phase morphology, network formation, interfacial compatibility, and durability evolution. Existing studies indicate that SBS mainly improves elastic recovery and high-temperature deformation resistance. In contrast, SMC can enhance workability, low-temperature flexibility, and construction compatibility. Their composite modification shows strong potential for balancing high-temperature, low-temperature, fatigue, and aging performance. However, current studies are still limited by insufficient quantitative comparisons, unclear microstructural mechanisms, and the lack of unified evaluation methods. Future studies should establish multi-scale structure–property–durability models. The modifier dosage range should also be optimized. This review provides a systematic reference for the development of high-performance and sustainable polymer-modified asphalt materials. Full article

Incorporating viscoelastic inclusions enhances the damping capacity of cementitious composites, but is often hindered by strength degradation and weak interfacial bonding. This study addresses this trade-off by investigating the synergistic modification of a cement matrix using carboxylated styrene-butadiene rubber latex (XSBRL) and chlorinated rubber (CR) powder, focusing on the age-dependent evolution of their joint energy-dissipation mechanisms. Macroscopic mechanical and microscopic test results reveal a pronounced synergy between latex and rubber powder, governed by possible interfacial interaction. The XSBRL film formed during hydration improves the compatibility between chlorinated rubber and the cement matrix, while its active groups further strengthen the bonding with hydration products. This interfacial coupling transforms the conventionally brittle transition zone into a ductile, high-friction network that maximizes dynamic stress transfer. Moreover, the temporal evolution of damping is governed by the competitive kinetics between cement hydration and polymer-film coalescence, shifting from early-age restructuring (7 to 14 days) to late-stage stabilization (28 days). To balance mechanical and dynamic properties, a recommended formulation of 10% XSBRL and 10% chlorinated rubber is established. This work provides a reference for clarifying the structure–property relationship of high-damping cementitious composites and for optimizing their mix designs. Full article

This study presents a photocatalytic infiltration pavement block designed to combine roadside NO_x removal with rainwater capture and temporary storage. TiO₂ and styrene–butadiene rubber (SBR) latex were incorporated into the pavement block to provide photocatalytic functionality, and direct infiltration holes were introduced to capture surface runoff, enable temporary storage, and promote delayed subgrade drainage. The effects of TiO₂ and SBR latex on compressive strength and NO_x removal were evaluated, while rainwater infiltration performance was examined using acrylic panels with different hole diameters, hole-area ratios, slopes, and V-groove treatments. The use of SBR latex improved the compressive strength of TiO₂-containing mixtures, with T10-L5 showing an 8.1% increase compared with the corresponding non-latex mixture. The same mixture achieved the highest NO_x removal efficiency, reaching 73.0% after 60 min of UV exposure. In the infiltration test, the 5 mm hole configuration gave the most stable runoff reduction, and lattice-type V-grooves improved water capture by connecting adjacent holes and guiding surface flow. A field-scale trial installation confirmed that the integrated infiltration–retention system suppressed visible ponding and runoff, provided delayed subgrade drainage, and maintained pavement stability under vehicle loading. The findings indicate that the proposed block system can provide combined air-purification and stormwater-control functions. Full article

This study explores the energy-harvesting performance of aluminum (Al)- and iron (Fe)-filled styrene–butadiene rubber (SBR) composites, with a focus on their mechanical durability and triboelectric properties. Comprehensive mechanical characterization—including tensile strength, elongation at break, fracture toughness, and elasticity—reveals that Fe-filled composites exhibit significantly enhanced reinforcement compared to Al-filled systems at equivalent filler loadings. Raman spectroscopy indicates that Fe atoms can coordinate with the benzene rings of SBR chains through stronger physicochemical bonding, a feature less present in Al-based composites. In addition to improved mechanical properties, Fe-filled composites demonstrate higher electrical conductivity and superior triboelectric energy-harvesting performance. Notably, the composite containing 15 vol% Fe under 1% cyclic compressive strain achieves a peak current density of 127.05 µA/m², a total generated charge of 5.01 nC, and a peak power density of 48.22 µW/m². These values represent substantial enhancements of 246%, 236%, and 2398%, respectively, compared to Al-filled counterparts. Cyclic energy-harvesting tests confirm stable performance with negligible degradation in output or mechanical integrity over repeated cycles. Rubber composite shows good humidity resistance in current and voltage outputs. Furthermore, a layer-by-layer triboelectric nanogenerator (TENG) based on the Fe-filled composite produces output signals of approximately ±1.0 µA and ±5 V under biomechanical hand patting. The superior performance of Fe-based composites is attributed to stronger filler–rubber interactions, likely facilitated by electrostatic interactions, which enhances interfacial charge transfer during mechanical deformation. Overall, Fe-filled SBR composites demonstrate strong potential for cost-effective, environmentally friendly, and durable self-powered energy-harvesting applications. Full article

Conventional rubber-modified asphalt faces critical limitations, including phase separation and compromised low-temperature flexibility, which typically restrict rubber content to 15–25%. This study investigates the viscoelastic rheology and fatigue life prediction of asphalt binders modified with 20% waste tire rubber, utilizing a chemical–thermal desulfurization process and a synergistic styrene–butadiene–styrene (SBS) composite. Five binders were evaluated: base asphalt (BA), SBS-P, WTR, WTD, and WTC. The WTC exhibited the highest softening point at 89 °C and a ductility of 35 cm, successfully overcoming the traditional stiffness–flexibility trade-off. Dynamic shear rheometer (DSR) tests revealed a 440% increase in complex shear modulus (G*) at 58 °C 10.8 kPa vs. 2.0 kPa for BA and a 13.2% reduction in phase angle (61.2°). Multiple stress creep recovery (MSCR) results showed WTC achieved a 60% recovery rate at 0.1 kPa and maintained 25% at 3.2 kPa, with non-recoverable creep compliance (J_nr3.2) well below the 1.0 kPa⁻¹ threshold for heavy traffic. Bending beam rheometer (BBR) tests confirmed WTC low-temperature suitability, achieving a creep stiffness of 280 MPa and an m-value of 0.58 at −24 °C. Furthermore, viscoelastic continuum damage (VECD) modeling demonstrated that WTC increased yield stress by 80.8% (470 kPa) and extended fatigue life by over two orders of magnitude at low strain (2%) compared to BA. Finally, WTC exhibited excellent storage stability, with a softening point difference (SPD) below 2.2 °C. These findings confirm that the rubber/SBS composite provides a highly durable, storage-stable, and fatigue-resistant binder suitable for long-life asphalt pavements under extreme climatic and heavy-traffic conditions. Full article

Acrylonitrile butadiene styrene (ABS) is widely used as an engineering plastic, but its extensive use generates a significant amount of waste that is difficult to recycle due to the material’s complex composition. In this study, the physical recycling of ABS using the dissolution technique has been employed to separate the pure copolymer of styrene and acrylonitrile (SAN) from polybutadiene rubber (PBR) and other substances. The relationships between the properties and composition of the original ABS materials were investigated as a starting point and for reference values to evaluate the effects of recycling on the quality and safety of recycled materials. Three different ABS materials were used in the recycling process from which pure SAN polymers were produced. The recycled SANs were then melt-blended with fresh masterbatch. The final ABS materials had the same composition, which facilitated investigation of whether the use of SAN recycled from different sources results in any differences in the properties of the final ABS material. The results showed that all the properties of ABS materials made with recycled SAN are similar regardless of the source of SAN. Several chemical substances were quantified in the original ABS materials and in SAN polymers obtained through the recycling process. The substances were largely removed from all materials except one. The main conclusions from this study are that the quality of ABS materials made with recycled SAN is at the same level as that of virgin ABS and is independent of the source from which SAN comes. This study has also shown that chemical safety is satisfactory because the physical recycling process is able to remove most of the substances that were present in the original ABS materials. Full article

To address the insufficient low-temperature performance of asphalt modified with direct coal liquefaction residue (DCLR), this study proposed a composite modification strategy based on an extraction–blending process using styrene–butadiene–styrene (SBS) and crumb rubber (CR). The high- and low-temperature rheological properties, phase morphology, and functional-group characteristics of DCLR-blended asphalt with different formulations were systematically evaluated using a dynamic shear rheometer (DSR), a bending beam rheometer (BBR), fluorescence microscopy (FM), and Fourier transform infrared spectroscopy (FTIR). The results demonstrate that the combined addition of SBS and crumb rubber significantly enhances the high-temperature stability and elastic response of the asphalt. Specifically, formulation 5# (8 wt.% SBS and 10 wt.% CR) maintained a rutting factor of 1.007 kPa at 82 °C, indicating superior high-temperature rutting resistance. Meanwhile, this formulation satisfied the Superpave low-temperature requirements at −18 °C, achieving a balanced improvement in both high- and low-temperature performance. Microstructural analysis suggests that an appropriate SBS/CR ratio contributes to the formation of a relatively continuous and uniformly distributed polymer-rich phase, whereas excessive modifier contents may lead to rubber agglomeration and phase-structure imbalance. FTIR results showed that the characteristic absorption peaks of the modified binders were generally consistent with those of the base asphalt, and no obvious new absorption bands were observed. This indicates that the extraction–blending process mainly involved physical blending, swelling, and phase interaction rather than the formation of new covalent functional groups. This study provides a technical reference for the high-value utilization of DCLR and the development of high-performance modified asphalt. Full article

This study aims to systematically evaluate the balancing mechanism between road performance, carbon emissions, and economic cost when selecting asphalt materials for severe cold regions, filling the gap in multi-criteria decision-making for composite chemical modifications. To address alternating temperatures, heavy traffic, and modified asphalt transport difficulties, this study presents a novel evaluation framework focusing on the performance–environmental–cost nexus of a desulfurized rubber powder composite SBS-modified asphalt mixture, which provides a clear technological breakthrough for high-ratio scrap tire recycling in seasonal frost zones. Two reference mixtures serve as comparisons: a conventional rubber powder composite SBS (styrene–butadiene–styrene triblock)-modified asphalt mixture (CR-SBS) and an SBS-modified asphalt mixture (SBS). A comparative experiment was conducted between the two materials and the SBS-modified asphalt mixture (ACR-SBS) compounded with desulfurized rubber powder. High-temperature stability was tested by the rutting test, low-temperature crack resistance by the beam bending test, and water stability by the immersion Marshall and freeze–thaw splitting tests. Life cycle carbon emissions and economic costs were quantified from raw material acquisition to construction. The results show that desulfurized rubber powder composite with ACR-SBS delivers the most superior overall road performance. However, it also generates the highest life cycle carbon footprint. Its total carbon emission reaches 162,800 kgCO₂eq, which is 13.7% (19,600 kgCO₂eq) higher than SBS (143,200 kgCO₂eq) and 7.7% (11,600 kgCO₂eq) higher than CR-SBS (151,200 kgCO₂eq). The total cost of ACR-SBS is 391,000 CNY, which is 1.5% (6000 CNY) higher than SBS (385,000 CNY) and 1.3% (5000 CNY) lower than CR-SBS (396,000 CNY). These findings provide a basis for the selection of high-performance, low-carbon, and economical composite-modified asphalt in severe cold regions. Full article

The emergence of a novel crumb rubber (CR)/SBS-polymerized pellet has simplified the complex preparation process of composite-modified asphalt. However, the effectiveness of CR/SBS-polymerized pellets in improving asphalt performance has not been confirmed. This study mainly investigated the performance and reinforcement mechanism of polymerized pellet-modified asphalt. First, polymerized pellet-modified asphalt samples with different contents (10%, 20%, 30% and 40% of the asphalt mass) were prepared. Then, the physical properties, rheological behavior, thermal stability, and aging resistance of the pellet-modified asphalt samples were systematically evaluated, using both base asphalt and a commercially available styrene–butadiene–styrene triblock copolymer (SBS)-modified asphalt as control groups for comparison. Finally, the modification mechanism was explored through Fourier transform infrared spectroscopy (FTIR) and fluorescence microscopy (FM). The findings demonstrated that the incorporation of polymerized pellets could effectively decrease the penetration, elevate the softening point, and enhance the viscosity of asphalt. In addition, the high- and low-temperature performance, as well as the aging resistance of the modified asphalt, were significantly improved. These enhancing effects became more pronounced with increasing modifier content. The performance of SBS-modified asphalt is between 20% pellets MA and 30% pellets MA. The pyrolysis temperature range of all asphalt samples is 220 °C~500 °C, and infrared spectroscopy indicated that CR/SBS pellet-modified asphalt is mainly a physical mixing process. This work provides a scientific basis for further engineering applications of CR/SBS pellets. Full article

This paper examines how international crude-oil price movements are transmitted to natural-rubber prices through the petrochemical–synthetic-rubber chain, with implications for Thailand as the world’s leading natural-rubber exporter and China as the dominant consumer. Using monthly data from April 2003 to March 2026 on the OPEC reference basket, butadiene, styrene–butadiene rubber (SBR), and the Shanghai natural-rubber benchmark, the analysis combines a nonlinear ARDL specification with a Pesaran–Shin–Smith bounds test, a long-run association decomposition into direct and synthetic-rubber-mediated components with bootstrap inference, and a threshold-NARDL extension that conditions the decomposition on the inventory state. Three findings stand out. First, the synthetic-rubber-mediated component accounts for approximately three-quarters of the estimated oil–natural rubber long-run association (73.5 percent, 95 percent bootstrap CI [60.6, 87.2]), with the residual direct component accounting for the remainder. Second, long-run pass-through is directionally consistent with concentration in the synthetic-rubber component, although Wald tests do not reject symmetry at conventional levels for either the synthetic-rubber component (Wald $p=0.135$) or the direct oil component ($p=0.166$). Third, the synthetic-rubber-mediated share is consistently larger in low-inventory regimes by 26 to 66 percentage points across three alternative regime variables, although the magnitude amplification of asymmetric pass-through itself is not robust. Asymmetric local projections and a Diebold–Yilmaz spillover analysis are reported as complementary horizon-indexed and network checks. The results imply that the synthetic–natural rubber spread, conditioned on the inventory state, may be more informative for natural-rubber price-risk monitoring than crude-oil prices alone. These findings have implications for commodity price-risk monitoring, export-income exposure, and stabilisation design in rubber-exporting economies. Because crude-oil shocks are not externally identified, all estimates are interpreted as decompositions of long-run association rather than causal mediation effects. Full article