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Styrene butadiene rubber (SBR) composites reinforced by cryptocrystalline graphite (CG) and multi‐wall carbon nanotubes (MWCNTs) were prepared. The SBR composite with 50 phr CG content displays superior mechanical reinforcement achieving 20.7 MPa in tensile strength. However, the electrical conductivity enhancement is modest. After incorporating MWCNTs as a secondary filler, the electrical conductivity significantly improved. The results show that the electrical conductivity of the SBR composite reinforced with 10 phr of CG and an additional 5 phr of MWCNTs surpasses that achieved by using 50 phr of CG solely. This enhancement can be attributed to the inherent excellent electric conductivity and high aspect ratio of MWCNTs, with their presence also preventing the re‐agglomeration of CG. Furthermore, within 10–40 phr content of CG, the mechanical reinforcement of CG‐SBR composites is enhanced with the addition of MWCNTs, whereas a minor decline in tensile strength is noted when the concentration of CG above 40 phr. Overall, the SBR composite reinforced with a synergistic combination of CG and MWCNTs is achieved, demonstrating both exceptional mechanical and conductive properties. Highlights: Styrene butadiene rubber (SBR) composites with different cryptocrystalline graphite (CG) phr and additional multi‐wall carbon nanotubes (MWCNTs) were characterized.CG‐SBR displays good mechanical property but limited electrical conductivity.Proper ratio of CG/MWCNTs significantly enhances various properties.MWCNTs act as a "bridge" structure connecting isolated CG filler in SBR matrix.MWCNTs network effectively prevents the re‐agglomeration of CG nanosheets. [ABSTRACT FROM AUTHOR]

A self‐developed Serial Rubber Continuous Mixing Device (SRCMD) based on the shear and elongation flow fields was adopted to continuously prepare the carbon nanotubes (CNTs)/expanded graphite (EG)/Solution‐polymerized styrene butadiene rubber (SSBR) composite. Meanwhile, the silanization reaction between the Silica and Si69 was introduced to improve the performance of the CNTs/EG/SSBR composite. When comparing the sample prepared using the two‐stage mixing process based on the shear flow field in the internal mixer, the continuously prepared CNTs/EG/SSBR composite with 3 wt% CNTs and 15 wt% EG demonstrates a higher thermal conductivity of 1.32 W/m·K. At the same time, it exhibits significant advantages in terms of mechanical properties, processability and dispersion rating. In addition, the mechanism for the continuous preparation of CNTs/EG/SSBR composite was revealed through visual experiments. This study aims to achieve the real continuous production of high‐performance thermally conductive polymer composites to meet the urgent demand for thermal conductivity materials in 5G technology. Highlights: Real continuous preparation of CNTs/EG/SSBR composite was realized.The silanization index of 92.26% between Silica and Si69 was achieved.Good silanization promotes the construction of thermal conductivity networks.High‐performance CNTs/EG/SSBR composite with low Payne effect was obtained. [ABSTRACT FROM AUTHOR]

The quantity of silane chemically bonded to the organoclay's surface significantly influences its dispersion within the polymer matrix, as well as the interfacial interaction. This research presents a groundbreaking method for enhancing the surface properties of montmorillonite (Mt) through the use of γ‐(methacryloxy) propyl trimethoxy silane (KH570) coupled with acid treatment, leading to increased grafting efficiency. Confirmed by FT‐IR, TGA, and XRD, the process effectively bonds organo‐silanes to Mt and achieves a high grafting level of 1.59 mequiv/g. Utilizing a latex compounding method, Mt/rubber nanocomposites are synthesized with thoroughly modified clay for peak performance. Dispersion and interfacial properties are evaluated through XRD, TEM, AFM, and DMTA. The findings reveal that the well‐modified Mt is an exceptional filler, ensuring a high level of dispersion and robust interaction with the rubber matrix. This synergy translates to a marked improvement in the mechanical properties of the composite, with notable enhancements observed in both tensile strength and elongation at break of 9.7 MPa and 1141%, respectively. This innovative approach to the graft modification of clays presents a potent method, offering the potential for the industrial‐scale manufacture of high‐performance clay‐based composites. Highlights: A processing method for preparing high grafting clay with a silane coupling agent.Functionalized clay presents better nano‐dispersion in the polymeric matrix.Strong covalent interfacial interaction is constructed between clay and rubber.Tensile Strength and elongation at break of the composites are obliviously improved. [ABSTRACT FROM AUTHOR]

The thermodynamic incompatibility between the soft and hard segments of thermoplastic polyurethane (TPU) results in a microphase‐separated behavior and excellent mechanical properties. However, the effect of the chain extender on the degree of microphase separation (DMS) and the resultant mechanical properties of TPU have not been well studied because of the complex interactions between the soft and hard segments. Herein, hydroxyl‐terminated polybutadiene‐based TPUs(HTPB‐TPUs) without hydrogen bonding between the soft and hard segments are synthesized using hydroxyl‐terminated polybutadiene, toluene diisocyanate, and four different chain extenders, and the effect of the chain extender structure on DMS is analyzed experimentally using a combination of analytical techniques. Furthermore, the solubility parameters of the soft and hard segments, glass transition temperatures, and hydrogen‐bond density of the HTPB‐TPUs, are computed using all‐atom molecular dynamics simulations. The results clearly reveal that the chain extender significantly affects the DMS and thus the mechanical properties of HTPB‐TPUs. This study paves the way for studying the relationship between the structure and properties of TPU. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highlights This article investigates the impact of magnetic particle content and various secondary carbon‐based filling materials on the mechanical properties, microstructure, magnetism, and viscoelasticity of magnetorheological elastomers (MREs) derived from natural rubber (NR) and butadiene rubber (BR). MREs composites with different formulations were prepared by using NR/BR blend (abbreviated as NB) as matrix and introducing carbonyl iron powder (CIP), few‐layer graphene (FLG), and carbon nanotube (CNT) as reinforcing fillers. The compressive mechanical properties, magnetorheological effect (MR Effect) and stress relaxation behavior of MREs under magnetic field were analyzed through microstructure characterization and macroscopic properties testing. The experimental results show that compared with the samples added CIP, FLG, and CNT, NB‐60CIP‐FLG has the best performance, which significantly improves the tensile mechanical properties, the stress of 300% set elongation is increased by 336.3%, the compressive properties are significantly increased by 92.7%. The performance of the NB‐60CIP‐CNT is also excellent, its 300% set elongation stress increased by 323.4%, in addition, its compression performance significantly improved by 79.2%. After the addition of the magnetic field, MR effect and magnetic response performance of the NB‐60CIP‐CNT sample were improved by 75.2% and 6.3%, while the MR effect and magnetic response performance of the NB‐60CIP‐FLG sample were improved by 49.9% and 18.8% compared with NB‐60CIP. In addition, the damping performance of secondary carbon‐based filling materials on MREs is also improved. This article discusses the influence of CIP content, filler type, and magnetic field intensity on the performance of MREs, highlighting its considerable importance for practical applications in production. MREs composites were prepared by using NR/BR blend as matrix. Carbonyl iron powder and graphene were used as reinforcing fillers. The carbon‐based fillers has improved the mechanical properties of MREs. The magnetic field has a significant effect on the performance of MREs. [ABSTRACT FROM AUTHOR]

This investigation delves into the potential utilization of Tire Reclaimed Rubber (TRR) as a filler within Natural Rubber/Styrene Butadiene Rubber (NR/SBR) blends. TRR is obtained from discarded rubber tires and stands as a pertinent resource that necessitates its effective utilization in the production of eco-friendly, value-added rubber-based products. This is due to the rising of rubber waste tires which causes environmental concerns and all sorts of pollution. The TRR filled NR/SBR blends were fabricated using two-roll mills. The loadings of TRR were varied ranging from 20 phr to 100 phr. The aim of this study is to investigate the influence of TRR loading on the cure characteristics and mechanical properties of blends in terms of tensile strength, rebound resilience, hardness, and density. It is found that the MH and Δ torque exhibited a decreasing trend which would indicate a reduction in crosslink density due to high loading of TRR. Meanwhile, the ts2 and tc95 increased with the increase of TRR loading. Furthermore, the tensile strength, hardness, density, and rebound resilience of blends experience a steady reduction with the incorporation of TRR. The decrement of those properties might be due to the low molecular weight of TRR. Regarding the collective findings, TRR emerges as a potentially viable candidate for waste rubber repurposing, serving as a non-reinforcing filler with optimal utility achieved at a 30 phr loading level. [ABSTRACT FROM AUTHOR]

Flexible strain sensors are attracting attention in areas such as medical monitoring sensing and rehabilitation therapy monitoring due to their powerful ability to sense, process, transmit and display complex information. However, it is an urgent challenge to realize the trade‐off between excellent performances such as high sensitivity, high linearity, wide strain sensing range and high durability. Herein, we prepare stretchable conductive composites with wrinkle composite micro‐crack structure by combining carboxystyrene butadiene rubber (XSBR) layer and carboxymethyl cellulose@Ag nanowire‐CNTs (CMC@AgNWs‐CNTs) conductive layer. Based on interfacial interactions, it can be adapted to different needs by adjusting the thickness of the strain sensing layer. When the thickness of the strain sensing layer is 4 μm, the strain sensor has a wide sensing range (strain capacity up to 300%) and high sensitivity (strain sensing factor of 484). At a thickness of 8 μm, the strain sensing performance exhibits a wide strain range, high linear fit and good cyclic stability. This work provides a new research idea to improve the comprehensive performance of flexible strain sensors and the contradiction between wide sensing range, high sensitivity and high linearity. [ABSTRACT FROM AUTHOR]

Polypropylene is a useful and widely consumed thermoplastic with very good properties that can be mixed with a combination of rubber and nanoparticles in order to eliminate its shortcomings. In this paper, the simultaneous combination of both the toughening effect of styrene–butadiene rubber (SBR) and the reinforcing effect of silicon carbide (SiC) nanoparticles were investigated in polypropylene matrix. Mechanical properties (tensile and impact strength [TS and IS]) of compounds were analyzed using the central composite design approach in Design‐Expert software. With two factors for input variables of SBR and SiC weight percentages, and their five levels (5, 10, 15, 20, and 25) and (0, 1.5, 3, 4.5, and 6), respectively, the central composite design approach employs 11 experiments for creation of models and the analysis of variance investigations with two output responses of TS and IS. Statistical results revealed that SBR and SiC contents had a significant effect on TS, IS, and the microstructure of compounds, as confirmed by scanning electron microscopy and energy‐dispersive spectroscopy images. To maximize all mechanical properties simultaneously with desirability functions, TS and IS of the optimum sample were computed to be 21.98 MPa and 8.66 kJ/m2 in amounts of 13.45 and 2.80 weight percentage (wt%) of SBR and SiC, respectively. Highlights: By increasing silicon carbide (SiC) in polypropylene/styrene–butadiene rubber (SBR), tensile strength decreases after a peak due to agglomeration effect.By increasing SiC in polypropylene/SBR, impact strength decreases after a peak due to agglomeration effect.By increasing SiC, the rubber particles' dimensions decrease according to scanning electron microscopy analysis.Simultaneous maximum of tensile strength and impact strength are 21.98 MPa and 8.66 KJ/m2, respectively.Optimum value of SBR and SiC in above maximums are 13.45 and 2.8 wt%, respectively. [ABSTRACT FROM AUTHOR]

Real‐time detection of different physiological characteristics is crucial for human physical and mental health. A detection system with multimodal sensing capability, high sensitivity, excellent mechanical properties, and environmental stability is highly desirable, but it is still a great challenge. Inspired by the structural gradient of biological tissues, a multifunctional sensor based on carboxylic styrene butadiene rubber (XSBR) and sodium polyacrylate (PAANa) non‐covalently modified MXenes is prepared in this study, in which the MXenes exhibit a gradient distribution and simultaneously formed an orientation arrangement at the bottom of the matrix through the formation of hydrogen bonding interactions with PAANa. The material shows a considerable stretchability of 244% and strength of 7.67 MPa, high electrical conductivity of 55.40 S m‒1, low percolation threshold of 2.48 wt%, and excellent response to strain (gauge factor of 906.7 within 98% strain) and humidity (relative resistance change of 530% within 11–93% relative humidity). Based on the superior performances of the XSBR/PAANa/MXene composite, an integrated detection system is designed to accurately detect respiration and body movements at various scales. This work provides a new perspective for the development of a novel biomimetic functional material for sensor applications. [ABSTRACT FROM AUTHOR]

Coordinative chain transfer polymerization (CCTP) of ethylene and its copolymerization with 1,3‐butadiene is conducted in toluene at 80 °C using a combination of {(Me2Si(C13H8)2)Nd(μ‐BH4)[(μ‐BH4)Li(THF)]}2 (1) metal complex and various organomagnesium compounds used as chain transfer agents including n‐butyl‐n‐octyl‐magnesium (BOMAG), n‐butyl‐mesityl‐magnesium (n‐BuMgMes), n‐butyl‐magnesium chloride (n‐BuMgCl), n‐pentyl‐magnesium bromide (n‐C5H11MgBr), pentanediyl‐1,5‐di(magnesium bromide) (PDMB) and isobutyl‐magnesium chloride (i‐BuMgCl). Kinetics and performance in terms of control of the (co)polymerization are comparatively discussed particularly considering the presence of ether and the nature of the organomagnesium compounds employed. Taking advantage of the well‐known reactivity between nitrile and molecular organomagnesium compounds, the functionalization of the chains is further carried out by deactivation of the polymerization medium with benzonitrile or methoxybenzonitrile compounds leading to ketone ω‐functionalized chains. The success of the functionalizations is extended to coupling strategies using dinitrile reagents and to the functionalization of high molar mass ethylene butadiene rubber (EBR). [ABSTRACT FROM AUTHOR]

The rheological properties of polymers before and after mixing are of primary concern because of the damage to the original molecular weight of polymers during processing. In order to reveal the correlation between mixing speed, rheological properties of polymer melts, and their molecular weight parameters, different grades of polybutadiene rubber (BR) at different mixing speeds were prepared in this study. Furthermore, the selected samples were subjected to the dynamic melt viscoelasticity test using a rubber process analyzer (RPA). The molecular weight changes of BR after mixing were observed on a rheological basis to analyze the effects of mechanical shear and thermo-oxidative aging on the molecular weight and distribution of the rubber. The measured values were directly compared with those obtained from gel permeation chromatography (GPC). The results showed that lower mixing speeds did not significantly affect the number-mean molecular weight (Mn), while the Z-mean molecular weight (Mz) and the weight-mean molecular weight (Mw) were increased, and the molecular weight distribution (MWD) was expanded. In addition, a transition state between thermo-oxidative aging and mechanical shear was further demonstrated. The behavior of the rubber was further elucidated and validated through large-amplitude oscillatory shear (LAOS) tests and thermal stability tests, demonstrating that the gel is a manifestation of the molecular weight coalescence of rubber and associating it with the mixing process of BR. According to the results of the RPA tests, melt rheology characterization is an environmentally friendly and fast way to provide information about the molecular structure of the BR. [ABSTRACT FROM AUTHOR]

In the quest for environmentally benign battery technologies, this study examines the microstructural and transport properties of water‐processed electrodes and compares them to conventionally formulated electrodes using the toxic solvent, N‐Methyl‐2‐pyrrolidone (NMP). Special focus is placed on sulfur electrodes utilized in lithium‐sulfur batteries for their sustainability and compatibility with diverse binder/solvent systems. The characterization of the electrodes by X‐ray micro‐computed tomography reveals that in polyvinylidene fluoride (PVDF) Lithium bis(trifluoromethanesulfonyl)imide/NMP, sulfur particles tend to remain in large clusters but break down into finer particles in carboxymethyl cellulose‐styrene butadiene rubber (CMC‐SBR)/water and lithium polyacrylate (LiPAA)/water dispersions. The findings reveal that in the water‐based electrodes, the binder properties dictate the spatial arrangement of carbon particles, resulting in either thick aggregates with short‐range connectivity or thin films with long‐range connectivity among sulfur particles. Additionally, cracking is found to be particularly prominent in thicker water‐based electrodes, propagating especially in regions with larger particle agglomerates and often extending to cause local delamination of the electrodes. These microstructural details are shown to significantly impact the tortuosity and contact resistance of the sulfur electrodes and thereby affecting the cycling performance of the Li‐S battery cells. [ABSTRACT FROM AUTHOR]

Thermoplastic vulcanizates (TPVs) were prepared based on polypropylene (PP) and polybutadiene rubber (PBR) at different PP/PBR compositions (70/30 and 60/40). PP-grafted-maleic anhydride (PP-g-MA) was introduced into the TPVs at different concentrations (10 and 20%). The compatibilizing effect of PP-g-MA was demonstrated through cross-sectional morphology. PP-g-MA exhibited a suppressing impact on the coalescence of the rubber domains, leading to a finer and more uniform distribution of the PBR phase. Due to the higher rubber content, the compatibilizing effect was more pronounced for the 60/40 composition, which was on the verge of forming a co-continuous morphology. However, it was found that a higher PP-g-MA content is needed to effectively compatibilize the TPVs. Rheological results revealed opposing effects on the viscoelastic response of the system. However, the elastic response was intensified once higher content of PP-g-MA was used, suggesting its compatibilizing role. Dynamic mechanical analysis results proved the existence of opposing effects and revealed the profound compatibilizing effects of PP-g-MA, especially at higher content (20%). Izod impact strength exhibited moderate and notable enhancements in both TPV compositions by adding 10% and 20% of PP-g-MA, respectively, attributed to the highly increased compatibility of the PP/PBR TPVs, especially at higher levels of PP-g-MA content. [ABSTRACT FROM AUTHOR]

The active hydroxy-terminated liquid polybutadiene rubber (HTPB) can be prepared into a macromolecular initiator under appropriate conditions. The polymers with specific functions are connected to both ends of HTPB by the method of block copolymerization modification to form block polymers with diverse structures and rich functions. In this paper, the recent research progress of HTPB block polymers in improving the performance of rocket propellants, stimulation-responsive polymers, stretchable semiconductor materials and amphiphilic polymers are reviewed. The future of HTPB block polymers is also prospected. [ABSTRACT FROM AUTHOR]

The article focuses on synthesising a new nanocomposite incorporating ZnS filler and investigating its structure, optical properties and specific electrical conductivity. In this study, expanded perlite (EP) and butadiene rubber (BR) underwent simultaneous oxidative chlorophosphorylation and subsequent hydrolysis. ZnS nanoparticles were then grown on the crosslinked/ion-exchange composite (EP-PhBR) using the Successive Ionic Layer Adsorption and Reaction (SILAR) method, resulting in the ZnS/EP-PhBR nanocomposite. The structure of the nanocomposite was characterised through UV-Vis spectroscopy and X-ray diffraction analysis. Embedding ZnS nanoparticles in EP-PhBR caused a reduction in the optical band gap from 3.18 eV to 3.045 eV, signifying increased disorder in ZnS nanoparticles due to alterations in the nanocomposite's intermolecular structure. XRD studies revealed cubic crystal-structured ZnS nanoparticles with an average size of approximately 3 nm in the ZnS/EP-PhBR nanocomposite. The specific electrical conductivity (σ) at ambient temperature demonstrated the enhanced crystallinity of EP-PhBR, attributed to interfacial interactions with ZnS nanoparticles and the developed nanolayers. The ZnS/EP-PhBR nanocomposite exhibited favourable properties, making it a promising material for photocatalysis and solar cell applications. [ABSTRACT FROM AUTHOR]

Distinguished from traditional vulcanized rubber, which is not reusable, thermoplastic elastomer (TPV) is a material that possesses both the excellent resilience of traditional vulcanized rubber and the recyclability of thermoplastic, and TPVs have been widely studied in both academia and industry because of their outstanding green properties. In this study, new thermoplastic elastomers based on solution polymerized styrene butadiene rubber (SSBR) and thermoplastic elastomers (SEPSs/SEBSs) were prepared by the first dynamic vulcanization process. The high slip resistance and abrasion resistance of SSBR are utilized to improve the poor slip resistance of SEPSs/SEBSs, which provides a direction for the recycling of shoe sole materials. In this paper, the effects of different ratios of the rubber/plastic phase (R/P) on the mechanical properties, rheological properties, micro-morphology, wear resistance, and anti-slip properties of SSBR/TPE TPVs are investigated. The results show that the SSBR/TPE TPVs have good mechanical properties. The tensile strength, tear strength, hardness, and resilience of the TPVs decrease slightly with an increasing R/P ratio. Still, TPVs have a tensile strength of 18.1 MPa when the ratio of R/P is 40/100, and this reaches the performance of the vulcanized rubber sole materials commonly used in the market. In addition, combined with microscopic morphology analysis (SEM), it was found that, with the increase in the R/P ratio, the size of the rubber particles gradually increased, forming a stronger crosslinking network, but the rheological properties of TPVs gradually decreased; crosslinking network enhancement led to the increase in the size of the rubber particles, and the increase in the size of rubber particles made the material in the abrasion of rubber particles fall easily, thus increasing its abrasion volume. Through dynamic mechanical analysis and anti-slip tests, when the R/P ratio was 40/100, the tan δ of TPVs at 0 °C was 0.35, which represents an ordinary vulcanized rubber sole material in the market. The viscoelasticity of TPVs increased with the increase in the R/P ratio, which improved the anti-slip performance of TPVs. SSBR/TPE TPVs are expected to be used in footwear and automotive fields due to their excellent abrasion resistance and anti-slip performance. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aims to compare the difference in the swelling process between styrene butadiene rubber (SBR) and natural rubber (NR) in ScCO2. A high‐pressure visual stainless‐steel autoclave was used to carry out swelling measurements based on the sample dimensions. The swelling rates for both rubbers followed a first‐order kinetic model. The diffusion coefficient for CO2 was determined from the change in the swelling degree with time. The shrinking process for the expanded rubber obeyed a second‐order kinetic model. A 2‐level full factorial experimental design was employed to discuss the influence of variables on rubber swelling and CO2 diffusion. Temperature and pressure were found to have a great influence on the equilibrium swelling degree, swelling rate and diffusion coefficient. For both SBR and NR, the maximum equilibrium swelling degrees were observed at 120°C and 20 MPa, yielding values of 1.18 and 1.16, respectively. The maximum diffusion coefficient reached approximately 3 × 10−9 m2 s−1 for both types of rubber at 120°C and 8 MPa. The crosslink density failed to affect these three responses, but the volume of expansion and the shrinkage rate were found to significantly decrease and increase, respectively, with increasing crosslink density. The motion of polymer segments forced by ScCO2 led to rearrangement of the material structure, which governed the nature of swelling, expansion, and shrinkage. Due to a lower number of entanglements and a weak electrostatic interaction exists between CO2 and the π‐system, SBR can absorb more CO2 and easily restructure than NR under the same conditions, resulting in higher equilibrium swelling degree, larger expansion and faster shrinkage than NR. Highlights: Swelling of nature rubber and styrene‐butadiene rubber in ScCO2 is compared.Swelling degree is positively correlated with temperature and pressure.Diffusion coefficient increases with temperature but decreases with pressure.Swelling degree varies with rubber type, while CO2 diffusion dose not.Crosslink density significantly affects expansion and shrinkage of rubber. [ABSTRACT FROM AUTHOR]

The inadequate mechanical properties and limited low temperature adaptability of Hydroxy-terminated polybutadiene (HTPB) impose constraints on its practical utilization in solid propellant applications. In the present investigation, a pioneering approach involved the synthesis of a novel hyperbranched polysiloxane, denoted as HBPSi-NH2, which encompasses –NH2 groups and Si–O–C chains. The HBPSi-NH2 with its unique flexible Si–O–C segments, serving as the soft component in the crosslinked network, in conjunction with the curing agent TDI as the hard component, achieves a synergistic balance of rigidity and flexibility. The resulting HTPB composites not only demonstrate enhanced mechanical properties but also exhibit excellent low temperature adaptability. Remarkably, the HTPB composites exhibit excellent mechanical properties at both 25 °C (0.74 MPa ~ 2.08 MPa) and − 40 °C (1.77 MPa ~ 12.49 MPa). This enhancement can be ascribed to the abundant presence of functional groups, namely –OH and –NH2. These active groups significantly augment the cross-linking density within the HTPB system, also promote the formation of numerous hydrogen bonds, enhancing the strength of HTPB. Simultaneously, the abundant presence of Si–O–C flexible chain segments within HBPSi-NH2 enhances the reactivity of the HTPB molecular chains, not only improving the toughness of HTPB but also significantly reducing its Tg (− 65.95 °C to − 75.62 °C). Furthermore, this study establishes a pivotal direction for the design and synthesis of high-performance HTPB-PU materials. [ABSTRACT FROM AUTHOR]

When asphalt pavement is in practical use, it is prone to cracking and other diseases due to the long-term effects of load and climate and the restricted self-healing properties of the asphalt material. In order to improve the properties and durability of asphalt pavement, we introduced disulfide bonds into polyurethane (PU) in this study. We prepared polyurethane-modified asphalt (PUA) containing dynamic disulfide covalent bonds using polytetrahydrofuran (PTMG), polyethylene adipate (PEA), and hydroxyl-terminated polybutadiene (HTPB) as soft segments. Subsequently, the rheological properties, healing performance, and microstructure of the PUA were studied. The results indicated that the PU with disulfide bonds was integrated into the asphalt and had good dispersity. A cross-linked network structure formed between them. PUA with HTPB as the soft segment had excellent high-temperature deformation and low-temperature cracking resistance and a prominent advantage in durability. In comparison, PUA synthesized with PEA had better high-temperature performance and fatigue resistance, and PUA synthesized with PTMG had considerable low-temperature properties and stability. The disulfide bonds had a positive impact on the high-temperature performance, aging resistance, and healing properties of PUA through constant dynamic exchange and topological rearrangement effects. This study provides a reference for the preparation of PUA with ideal self-healing ability and has instructive significance for the selection of soft segment materials for synthesizing PUA. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Conveyor belts are used for material transportation in the mining and construction industries. The friction and wear properties of the styrene butadiene rubber (SBR) used in conveyor belts are investigated, including the effects of the applied load and rotational speed on the friction coefficient and weight loss. The sliding wear mechanism of the SBR is analyzed using scanning electron microscope, energy dispersive spectrometer, and Fourier transform infrared spectrometer. The results demonstrate that the friction coefficient and total weight loss of SBR increase as a function of rotational speed, whereas the friction coefficient decreases and the total weight loss increases as a function of increasing applied load. The maximum friction coefficient occurred at a loading of 10 N and a speed of 120 revolutions·min−1, and the maximum total weight loss occurred at a loading of 20 N and a speed of 120 revolutions·min−1. In comparison to the unworn surface, the worn surface of the SBR exhibits melting, adhesive, and abrasive wear characteristics. The increases in the hardness, yellowing, oxygen content, and the number of complex structures, such as hydroxyl, aldehyde, ketone, and ether groups, occur simultaneously. [ABSTRACT FROM AUTHOR]

In actual production processes, pure ethyl vinyl acetate (EVA) foams have a high shrinkage rate, and the foaming matrix is prone to plastic deformation, even causing the collapse of bubbles. This limits the further application of EVA foams. In this study, we incorporated styrene butadiene rubber (SBR) and butadiene rubber (BR) into EVA to improve the mechanical properties and dimensional stability of EVA composite foams without sacrificing their low-density characteristics of low density. We used a melting index meter, rotorless vulcanizing meter and dynamic mechanical analysis (DMA) to characterize the changes in viscosity and energy storage modulus of the composite matrix. Scanning electron microscopy (SEM) was used to study the microscopic morphology of foams. The mechanical properties test results showed that the addition of SBR reduced the density of EVA/SBR/BR composite foams, and the addition of BR improved the mechanical properties and dimensional stability of the foams. By combining the advantages of both, the density of products is comparable to pure EVA, the tensile strength and the compressive strength are increased by 11% and 6.3% relative to pure EVA, respectively. [ABSTRACT FROM AUTHOR]

The traditional batch synthesis of liquid rubber faces issues such as low monomer polymerization concentration, poor uniformity of the reaction system, and inadequate heat dissipation, resulting in an unsatisfactory synthesis efficiency. This study presents a method for the rapid and efficient synthesis of high vinyl 1,2‐polybutadiene liquid rubber using butadiene as the monomer and n‐butyllithium as the initiator. By applying continuous flow microchannel reactors, the limitation of traditional synthesis method can be overcome. The addition of a modifier in the raw material promotes the formation of high vinyl structure. The preparation of liquid rubber requires the addition of a large amount of metal lithium initiator. However, for aerospace sealants, there is a requirement for low metal ion content. To address this, we employed different methods to reduce the metal ion content in the liquid rubber and increase its purity. Ultimately, we achieved the synthesis of high‐purity polybutadiene liquid rubber with 1,2‐vinyl content exceeding 88%, narrow molecular weight distribution, and tunable molecular weights. This research will provide technical guidance for the industrial application of polybutadiene synthesis in continuous flow microchannel reactors. [ABSTRACT FROM AUTHOR]

3,4-Dinitrofurazanfuroxan (DNTF) is widely used in fusion-cast-based explosive carriers owing to its low melting point, high energy, and excellent stability. To reduce the susceptibility of DNTF and improve the thermal properties, core–shell composites (DNTF@PDA@HTPB) were synthesized using the oxidative self-polymerization reaction of dopamine. The results showed that hydroxyl-terminated polybutadiene (HTPB) was tightly coated on the surface of DNTF@PDA crystals, and the crystal structure of the high-energy crystals did not experience any significant changes during the encapsulation process. Compared with the raw DNTF, the thermal decomposition of DNTF in the DNTF@PDA and DNTF@PDA are delayed by 13.3℃ and 17.1℃, respectively. This phenomenon indicates that the thermal stability of DNTF@PDA and DNTF@PDA@HTPB composites is improved. The ignition speed of DNTF@PDA@HTPB is faster, and the flame activity is more vigorous. Meanwhile, the friction susceptibility of DNTF@PDA@HTPB is reduced by 44% compared to DNTF, and the impact susceptibility is significantly reduced by 75%. This study provides a new idea to improve fused-cast explosives' structure and combustion performance. [ABSTRACT FROM AUTHOR]

There are concerns regarding high surface temperatures on synthetic grass sports surfaces influencing the surrounding thermal environment, potentially increasing heat stress and impacting athlete safety. As such, studies have investigated changes to the thermal environment surrounding synthetic grass surfaces in comparison to both natural grass, and synthetic surfaces with different features, but this body of research has not been systematically reviewed. Therefore, this systematic review aimed to (i) determine if there are differences in the thermal environment surrounding synthetic grass surfaces compared with natural grass surfaces, and (ii) determine if there are differences in the thermal environment between different types of synthetic grass surfaces. A systematic review adhering to the PRISMA guidelines was performed. The eligibility criteria required investigations to report at least one of the following environmental parameters on or directly above both a synthetic surface and a comparator group of either natural grass or an alternative synthetic grass surface used in sport: Air temperature, mean radiant temperature, humidity, wind velocity, unified heat stress indices (i.e. wet-bulb-globe temperature and heat index) and/or surface temperature. Twenty-three studies were identified. The only parameters that were consistently higher on synthetic grass compared to natural grass were the air temperature (range: 0.5–1.2 °C) and surface temperature (range: 9.4–33.7 °C), while the mean radiant temperature, humidity, wind velocity and wet-bulb-globe temperature remained similar or required more data to determine if any differences exist. Synthetic grass surfaces consisting of styrene butadiene rubber infill or a shock pad had increased surface temperatures, whereas surfaces with thermoplastic elastomer infill, Cool climate turf fibres or HydroChill had lower surface temperatures. This systematic review has demonstrated that air and surface temperatures can be increased on synthetic sports surfaces, compared to natural grass surfaces. However, it is uncertain whether the differences are enough to increase an individual's heat stress risk and cause concern for athlete safety. While modifications to the turf infill or fibres can reduce synthetic surface temperatures, the effect of these features on the thermal environment as a whole is unclear. This review was prospectively registered with the Open Science Framework (Open Science Framework registration https://doi.org/10.17605/OSF.IO/BTKGE). [ABSTRACT FROM AUTHOR]

The stress-strain behavior of rubber compounds is one of the key items to determine its application performance, and the different service conditions, especially the strain rate, have variable requirements for the performance of rubber compounds. The influence of tension strain rate on the stress-strain behavior of styrene butadiene rubber (SBR) vulcanizates filled with 3 kinds of carbon black was investigated from the point of view of rubber reinforcement. It was found that the stress at a given elongation of any SBR vulcanizate increases with increasing strain rate, and the more reinforcing the carbon black, the higher increment rate the stresses. For any given SBR vulcanizate, the stress increment rate decreases with the increase in strain. As the strain exceeds the critical points, such as 300%, the effect of strain rate on the rate of stress increase is becoming equivalent and independent of carbon black grades. From a filler reinforcement point of view, the tensile modulus of filled vulcanizates in the plateau region is governed by the surface activity of the carbon black. In quasi-static tension test, the networking of carbon black in vulcanizate will be gradually broken with increasing strain, which the break-up is predominantly controlled by strain rather than strain rate. [ABSTRACT FROM AUTHOR]

Natural rubber (NR) composites have been widely applied in damping products to reduce harmful vibrations, while rubber with only a single composition barely meets performance requirements. In this study, rubber blend composites including various ratios of NR and styrene butadiene rubber (SBR) were prepared via the conventional mechanical blending method. The effects of the rubber components on the compression set, compression fatigue temperature rising and the thermal oxidative aging properties of the NR/SBR blend composites were investigated. Meanwhile, the dynamic mechanical thermal analyzer and rubber processing analyzer were used to characterize the dynamic viscoelasticity of the NR/SBR blend composites. It was shown that, with the increase in the SBR ratio, the vulcanization rate of the composites increased significantly, while the compression fatigue temperature rising of the composites decreased gradually from 47 °C (0% SBR ratio) to 31 °C (50% SBR ratio). The compression set of the composites remained at ~33% when the SBR ratio was no more than 20%, and increased gradually when the SBR ratio was more than 20%. [ABSTRACT FROM AUTHOR]

In this paper, statistical analysis and experimental methods are employed to study the hydrobromination of hydroxyl-terminated polybutadiene (HTPB) elastomer by 48% hydrobromic acid. The effect of three variables including time, temperature, and volume of acid, on the percentage of hydrobromination is investigated. The influence of these parameters and their interaction is checked through the analysis of variance and sensitivity analysis, and the optimum values for 10% hydrobromination are obtained 24 h, 30 °C, and 5.05 ml of the acid volume. A hydrobrominated resin is synthesized by applying optimal conditions for hydrobromination of 10% of double bonds. The results obtained from classical analysis and NMR show the amount of hydrobromination as 9.89% and 9.38%, respectively. The placement of the bromine atom in the compound is confirmed by ATR and NMR analysis. Also, DSC analysis shows that the glass transition temperature (Tg) of the hydrobrominated product increased by 2.86 °C compared to the initial HTPB. [ABSTRACT FROM AUTHOR]

Context: The thermal decomposition process of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine/hydroxyl-terminated polybutadiene (HMX/HTPB) hybrid explosives and pure HMX explosives at different temperatures (2000 ~ 3500 K) was investigated using the reactive molecular dynamics method. This study aimed to analyze the effect of binders on the thermal decomposition of HMX at the atomic scale and reveal the thermal decomposition mechanism of HMX/HTPB. The results showed that the thermal decomposition process of the HMX molecule in the HMX/HTPB hybrid system involves a continuous denitration followed by the disintegration of the main ring. The HTPB chain will experience dehydrogenation, dehydroxylation, and chain fragmentation. Including HTPB in the hybrid system significantly increased the presence of H and OH radicals. These radicals then interacted with HMX and its decomposition products and produced more of the final products H2O and H2 in the HMX/HTPB hybrid system compared to pure HMX. Additionally, it was observed that the HTPB chain fragments attached to the HMX decomposition products prevented the formation of N2 and CO2. Furthermore, the activation energies (Ea) of the initial and intermediate decomposition stages of the HMX/HTPB hybrid system were 98.45 kJ mol−1 and 90.69 kJ mol−1, respectively. The results showed that the activation energies of the HMX/HTPB hybrid system are lower than the pure HMX system in these two stages. Consequently, HTPB will enhance HMX's thermal decomposition and decreased the system's insensitivity to heat stimuli. Methods: The molecular dynamics simulation of the HMX/HTPB hybrid system was performed using the ReaxFF module in the LAMMPS software, and the ReaxFF/lg force field was used to describe the interatomic interactions as well as the chemical reactions. [ABSTRACT FROM AUTHOR]

We present linear viscoelastic data with anionically synthesized and critically fractionated polybutadiene (rich in vinyl content) rings having about Z = 22 entanglements. These rings are experimentally as pure as currently possible. They exhibit a power-law stress relaxation G(t) that is well-described by the state-of-the-art fractal loopy globule (FLG) model (power-law exponent of − 3/7). Previously reported data with polystyrene rings, prepared by anionic synthesis in dilute solution and purified by liquid chromatography at the critical condition, having Z = 14 entanglements, showed a power-law G(t) as well. Recent developments with different synthetic methods yielding not so well-characterized rings with a very large number of entanglements (up to 300), suggest that a rubbery plateau emerges in the linear viscoelastic response for Z > 15. Our work confirms the power-law G(t) with the FLG exponent with another chemistry and contributes to the current discussion about different regimes of rheological behavior, indicating that a possible deviation from the power-law FLG type of behavior toward rubbery plateau may occur for Z > 22. To fully capture the experimental G(t) data, the FLG model is complemented by two additional relaxation modes which are attributed to ring-ring (RR) and ring-linear (RL) threading, in accordance with recent reports in the literature. The faster RR mode likely reflects a new mechanism of stress relaxation not described by FLG, and the slower RL mode is attributed to synthetic and material handling imperfections (for example, due to thermal treatment). However, it does not change the punchline of the work: no rubbery plateau for entangled rings with up to 22 entanglements. Stress relaxation modulus for entangled ring polybutadiene (exhibiting power-law decay) and its linear precursor (exhibiting rubbery plateau), along with fits to the data: tube model for linear chains, and fractal loopy globule (FLG) with slow modes (RR and Tsalikis et al.) for the ring. [ABSTRACT FROM AUTHOR]

Carbon black (CB) is the most frequently applied conductive additive in rubber and polymer composites. This project aims to investigate the electrical/dielectric properties of a hybrid composite based on butadiene rubber and N-234 type of low-cost CB prepared via an oxidative chlorophosphorylation reaction. The properties are described by conductivity (σ) and dielectric constant (έ) frequency dependence at ambient temperature. The conductivity mechanism is explored based on the structure of CB and composite measured by X-ray powder diffraction analysis. Graphite-like structure and semi-crystalline intercalate phase were observed in the X-ray powder diffraction patterns of CB and composite, respectively. The σ and έ obtained values show the positive contribution of CB filler in the electrical/dielectric properties of the modified polymer through enhancing the crystallinity, providing a new conductive pathway with a higher probability of charge carriers tunneling and founding a higher polarized system based on the microscopic structure of obtained composite. A low-cost conductive/polarized composite of higher permittivity in comparison to a modified polymer was obtained. The composite is suggested for use in energy storage and electric devices. [ABSTRACT FROM AUTHOR]

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Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper describes a new active method of controlling the position of the burning surface of a solid fuel strand in an opposed-flow burner experiment. This method is designed to avoid biases to the combustion process introduced by retaining wires and to avoid experimental delays caused by wire failures. Regression rates are presented for hydroxyl-terminated polybutadiene fuel strands burning in various oxidizer streams. The active control method uses a control loop composed of a diode laser, a photodiode, and a stepper motor. For comparison, tests were also performed using the commonly used passive control method of spring-loading the fuel against a retaining wire. This active control method can only be used at high values of oxidizer mass flux; at low mass flux, soot accumulation obstructs the laser beam. In passive control tests, the retaining wire conducts heat from the flame into the fuel and increases regression rate. The presence of the wire also modifies the extinction limits of the flame. A model was developed for regression rate as a function of oxidizer mass flux, oxidizer composition, and retaining wire diameter. This model can be used to correct future regression rate data for the bias introduced by retaining wires. [ABSTRACT FROM AUTHOR]

The use of polymers is desirable in the industries where weight reduction and corrosion resistance are required, such as in the automotive industry where weight reduction directly relates to fuel conservation. Acrylonitrile butadiene styrene (ABS) is a type of polymer used in aerospace, railway, automotive, and consumer goods industries. This research article investigates the use of friction stir welding (FSW) to join ABS polymer. Compared to traditional metal-based products, polymers offer better formability, design flexibility, and ease of processing. The process parameters were optimized based on tensile strength using Taguchi's L18 orthogonal array (OA). A maximum tensile strength of 19.4 MPa was obtained at a tool rotational speed of 224 rpm, a tool travel speed of 40 mm/min, external heat of 45 °C, and a tool shoulder diameter of 16 mm. Transmission electron microscopy was used to analyze the microstructural characteristics, while Vickers microhardness tester and tensometer were used to examine the mechanical properties. The strength of the joint was affected due to the butadiene rubber particles breaking or weakening in the stir zone). Moreover, to identify the location of failure, three additional tensile coupons were taken from Experiment No. 13, and a 1-mm-deep notch was machined in all of them at the Center, AS, and RS. The findings revealed that the tensile coupon with the notch at RS had a tensile strength of 19.4 MPa, which is 60% relative to the base material. The retreating side of Experiment No. 13 exhibited a Vickers microhardness of 14.3 HV, which was higher than the base material's Vickers microhardness of 13.8 HV, indicating that it became harder. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance spectroscopy was employed to monitor the change in chemical structures, olefin units (cis, trans and vinyl) and hydroxyl value on stabilized Hydroxyl‐terminated polybutadiene (HTPB) under accelerated ageing condition. Thermal ageing of HTPB was carried out at 65 °C for 10‐weeks and periodically withdrawn sample for NMR analysis. 1H and 13C NMR spectroscopy provided detailed structural information for all HTPB samples, including the quantification of olefin units and the determination of hydroxyl value. The analysis revealed a decrease in signal intensity, particularly for the olefin near or at the molecular end, suggesting that they were oxidized before those in the middle position within the chain. The quantitative assessment of olefin units indicates a slight decrease of 2 % in 1,2‐vinyl unit after 10‐weeks of ageing. The NMR spectra did not show any detectable signals corresponding to epoxides, peroxides or alcohols in any HTPB samples. However, a slight increase in the OH value was observed after 8 and 10 weeks of ageing, suggesting the possible incorporation of new hydroxyl groups due to thermal‐oxidation. The antioxidants used to stabilize HTPB exhibited limited effectiveness in preventing degradation reactions, even after 4 weeks of ageing at 65 °C. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis of hydroxyl-terminated polybutadiene (HTPB) using ring-opening metathesis polymerization (ROMP) and different olefin metathesis catalysts. The authors investigated the use of various catalysts, including Grubbs first-generation catalyst (G1), Grubbs second-generation catalyst (G2), Grubbs third-generation catalyst (G3), Hoveyda-Grubbs second-generation catalyst (HG2), and a Z-selective olefin metathesis catalyst (HGZ). They found that G3 produced the most promising results, with rapid monomer conversion and relatively high end-group fidelity. The other catalysts required longer reaction times and produced greater aldehyde formation. The study suggests that rapidly initiating olefin metathesis catalysts like G3 may offer advantages for ROMP with a chain-transfer agent. [Extracted from the article]

Protective waxes are typically mixtures of paraffin and microcrystalline waxes that retard the aging of unsaturated rubbers and are widely used in rubber products. The wax solubility of rubber products is important for understanding the migration behavior and film formation of waxes and determining the appropriate wax content in rubber compounds. In this article, protective waxes were applied to natural rubber (NR)/polybutadiene rubber (BR) based sidewall rubber and the compatibility between NR and BR and the protective wax dissolution in these rubbers were investigated with a focus on the former investigation through Materials Studio simulations. It was found that the simulation results are strongly correlated with the wax migration test results on compounded and cured rubber at different NR/BR mass ratios. Blends and mesoscopic dynamics simulations yielded good compatibility between NR and BR and favorable blend morphology. By analyzing the solubility parameter, R value, mean square displacement and diffusion coefficient of wax chains with different lengths in the NR/BR matrix, the mechanism and reasons for the wax precipitation variation of protective waxes at varying NR/BR mass ratios were analyzed from a microstructural point of view, which provides strong theoretical support for the design of the molecular structure of protective waxes. [ABSTRACT FROM AUTHOR]

Talcum powder (Talc) contains large amounts of silica; however, its poor surface compatibility with diene rubber makes it difficult to develop its application in styrene‐butadiene rubber (SBR). Herein, a method to enhance the compatibility of Talc with SBR via interfacial sacrificial bonds of 4‐vinylpyridine and Mg2+/Zn2+ is proposed. Poly(isoprene‐co‐4‐vinylpyridine) copolymers, designated PIPVP‐10 and PIPVP‐20, were synthesized via reversible addition‐fragmentation chain transfer polymerization. PM1‐Talc and PM2‐Talc were obtained by spraying PIPVP‐10 and PIPVP‐20 solutions onto the Talc surface, followed by drying. During thermal vulcanization, the double bonds in the copolymers can be grafted directly onto the rubber skeleton. The vulcanization rates of the SBR/PM1‐Talc and SBR/PM2‐Talc complexes were accelerated by 65% and 77%, respectively, compared with that of SBR/Talc. Simultaneously, the interfacial interaction between SBR and Talc is enhanced owing to the formation of metal–ligand bonds between pyridine and Mg2+/Zn2+. As a result, the tensile strengths of SBR/PM1‐Talc and SBR/PM2‐Talc are 5.8 and 7.9 MPa, 65% and 127% higher than that of SBR/Talc (3.5 MPa). [ABSTRACT FROM AUTHOR]

Hydroxyl‐terminated polybutadiene (HTPB) is hydrogenated using catalytic hydrogenation with HTPB as a precursor using various catalysts. The hydrogenation is carried out using iso‐propyl alcohol (IPA) and toluene as an active solvent media. The present paper used (a) charcoal, (b) palladium supported by charcoal (Pd−C), (c) palladium supported by zirconium oxide (Pd‐ZrO2), and (d) copper chromite (CC) as catalysts for hydrogenation of HTPB to study the influence on the degree of hydrogenation with respect to each catalyst. The experimental data shows that hydrogenated HTPB (HHTPB) formation is predominantly controlled by physisorption and chemical reaction with a catalyst. Various techniques like NMR, FTIR and chemical analysis are used to characterize HTPB and HHTPB. Degree of hydrogenation of HTPB is found to be higher with copper chromite when compared to other catalysts in this work. Post‐hydrogenation, no significant change in hydroxyl value and a marginal increase in molecular weight is noticed with all catalysts. HTPB and HHTPB samples are analyzed using FTIR, 1H‐NMR, and 13C‐NMR and TG‐DSC studies, and inferences are derived with respect to the change in the olefinic region, microstructural changes, molecular weight, and thermal decomposition characteristics. [ABSTRACT FROM AUTHOR]

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The weak interfacial adhesion of aramid fibers (AFs) in rubber composites can be improved by modifying their surface structure. Herein, modified AFs with a high grafting rate were prepared by modification using glycidyl polyhedral silsesquioxane (POSS) assisted with supercritical carbon dioxide (scCO2). X‐ray photoelectron spectroscopy confirmed the chemical bonding between AFs and glycidyl POSS. Thermogravimetric analysis and scanning electron microscopy images showed that POSS was grafted uniformly and the surface roughness enhanced obviously. After grafting the rubber with 5 wt% glycidyl POSS assisted with scCO2, the surface grafting rate reached 12.26% and surface crystal spacing increased. The grafted layer on the modified AF surface was uniform, and the tensile strength of the modified fiber increased by 7.98%. Short AF‐reinforced carbon black/styrene butadiene rubber (AF/CB/SBR = 2/50/100 phr) composites were prepared to investigate the adhesion strength between modified AFs and SBR. The reduction in tan δ of the composites confirmed the improvement in the interfacial adhesion strength. The tensile strength and modulus at 100% elongation of the composites increased by 15.13% and 25.77%, respectively, and the relative interface slip increased by 23.26%. Moreover, the cutting resistance of the composites showed a dramatic improvement, particularly for grafting with 5% glycidyl POSS assisted with scCO2. © 2024 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Considering the high toxicity of toluene diisocyanate (TDI) and the low reactivity of isophorone diisocyanate (IPDI), a low‐toxicity curing agent, dimer acid diisocyanate (DDI), was used to cross‐link HTPB elastomers and propellants. The unique long‐chain structure of DDI not only ensures the elastic modulus and tensile strength of the elastomer, but also improves the flexibility to some extent. The long flexible chains promote the segment movement, which is very important for the formation of hydrogen bonds between segments. The chemical cross‐linking network and hydrogen bonding association play a significant role in the mechanical properties of the HTPB/DDI system. The relationship between the mole ratio of ‐NCO to ‐OH (R‐value) and the mechanical properties of HTPB/DDI elastomers were also investigated. In the range of R‐value from 0.85 to 1.2, the elastic modulus and tensile strength first increase and then decrease, and the elongation at break first decreases and then increases. Under the same curing conditions, the elastic modulus and tensile strength of the HTPB/DDI propellant are similar to the HTPB/TDI propellant. For the HTPB/AP/Al propellants and HTPB/AP/RDX/Al propellants, the HTPB/DDI system has lower burning rates in the range of 5–19 MPa than the HTPB/TDI system and HTPB/IPDI system. The application of DDI can reduce the burning rates of the propellant without adding any burning rate modifiers. It is considered that DDI can replace TDI and IPDI as a new curing agent with low toxicity and moderate reactivity for HTPB systems. [ABSTRACT FROM AUTHOR]

Pulverized coal (coal) possesses a layered structure similar to graphite and is a potential reinforcing filler. In this paper, ball milling is used to reduce the particle diameter of coal. The coal is modified with KH‐560 to obtain K‐COAL and prepared K‐COAL/styrene‐butadiene rubber (SBR) composites. In addition, carbon black (CB) is modified to obtain CB‐Si69, K‐COAL and CB‐Si69 are added to SBR in different ratios to prepare COAL/CB/SBR composites. The results show that the addition of K‐COAL can improve the vulcanization performance, thermal stability, and mechanical properties of SBR composites, but the reinforcing effect is weak. In the COAL/CB/SBR composites, the vulcanization and mechanical properties of the composites gradually increase with the increase of CB, while those of the thermal stability decrease. The tensile strength of the 10 phr COAL/30 phr CB/SBR composite is 24.1 MPa, which is elevated by 1105% and 205% compared with the pure SBR and 40 phr K‐COAL/SBR composites, respectively. The composites maintain high elasticity while the tensile strengths are greatly improved, and the mechanical properties are significantly enhanced. In conclusion, this paper provides a reference for the clean utilization of coal and shows new possibilities for finding new fillers to replace CB. [ABSTRACT FROM AUTHOR]

Effects of carbon nanotubes (CNTs) content and the in situ surface modification via bis(triethoxysilylpropyl) disulfide (Si75) and (3‐aminopropyl) triethoxysilane (KH550) on the rheological properties of rubber nanocomposites are explored. Results from the strain sweep demonstrate that the filler network of the nanocomposite is enhanced when the hydroxylated CNT (HCNT) is incorporated. The promotion of filler–rubber interaction in nanocomposite reinforced with modified CNT is validated by both stress relaxation and strain sweep measurements. The die swell ratio (B) declines with increasing HCNT content and rises with a heightened shear rate. Compared to those without HCNT, B of the nanocomposites, which contained 5 phr HCNT, decreased by 5.4%, 7.0%, and 17.3% at 50, 200, and 500 s−1, respectively. The Si75‐modified HCNT and the carboxylated CNT (CCNT) reduce the B‐value of the extrudates at 500 s−1 by 3.7% and 3.0%, respectively. However, the extrudates filled with KH550‐modified HCNT or CCNT showed a larger B due to pre‐crosslinking, as demonstrated by stress relaxation and swelling tests. Furthermore, it is also found that the application of KH550 has an acceleration effect on the curing reaction, increasing the curing efficiency by 8.5%. Highlights: The promotion of filler–rubber interaction is validated by RPA.The dimensional stability of the composites is improved after incorporating CNT.The extrudates with Si75 exhibit a reduced B and improved surface morphology.CNT content increase raises MH, ML, and shortens the t10 of the composite. [ABSTRACT FROM AUTHOR]

Zinc complexes have a considerable impact on human health and the environment, especially on aquatic wildlife. One of the primary sources of zinc release to the environment is worn rubber particles from tires. The environmental footprint of zinc oxide (ZnO) during production, use, and landfilling has prompted researchers to reduce its use in rubber formulations due to ecological and economic concerns. In this study, composite ZnO materials where ZnO particles are coated on precipitated calcium carbonate (CaCO3) are used in styrene butadiene rubber/butadiene rubber (SBR/BR) compounds, and their performance is compared with white seal ZnO and active ZnO. Trial compounds are prepared on a laboratory scale using composite ZnO materials with ZnO:CaCO3 ratios of 40:60, 60:40, and 90:10, and control compounds with white seal and active ZnO. All compounds are tested to evaluate their curing and physico-mechanical properties. It is observed that the surface area of ZnO plays an essential role in crosslink density and, hence, compound performance. Trial materials have no negative effect on the curing and mechanical properties of the compounds. Thus, it is concluded that composite ZnO materials can be used as alternatives to both white seal ZnO and active ZnO. They have environmental and economic advantages due to their lower ZnO content. The compound recipe has the potential to be used for tire tread compounds. [ABSTRACT FROM AUTHOR]

Incorporating aluminum metal-organic frameworks (Al-MOFs) as energetic additives for solid fuels presents a prom- ising avenue for enhancing combustion performance. This study explores the potential benefits of Al-MOF (MIL-53(Al)) ener- getic additive on the combustion performance of hydroxyl-terminated polybutadiene (HTPB) fuel. The HTPB-MOF fuel samples were manufactured using the vacuum-casting technique, followed by a comprehensive evaluation of their ignition and combus- tion properties using an opposed flow burner (OFB) setup utilizing gaseous oxygen as an oxidizer. To gauge the effectiveness of Al-MOFs as fuel additives, their impact is compared with that of nano-aluminum (nAl), another traditional additive in HTPB fu- el. The results indicate that the addition of 15% (mass fraction) nAl into HTPB resulted in the shortest ignition delay time (136 ms), demonstrating improved ignition performance compared to pure HTPB (273 ms). The incorporation of Al-MOF in HTPB also reduced ignition delay times to 227 ms and 189 ms, respectively. Moreover, under high oxidizer mass flux conditions (79-81kg/(m²s)), HTPB fuel with 15% nAl exhibited a substantial 83.2% increase in regression rate compared to the baseline HTPB fuel, highlighting the positive influence of nAl on combustion behavior. In contrast, HTPB-MOF with a 15% Al- MOF additive showed a 32.7% increase in regression rate compared to pure HTPB. These results suggest that HTPB-nAl out- performs HTPB-MOF in terms of regression rates, indicating a more vigorous and rapid burning behavior. [ABSTRACT FROM AUTHOR]