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The elasticity of polymer networks, formed by cross-linking high molecular mass polymers in the melt state and then swollen by a solvent, involves contributions from both the presence of cross-link network junctions and the interchain interactions associated with the combined effect of excluded volume interactions and topological constraints that become modified when the network is swollen. We test the capacity of the previously developed localization model of rubber elasticity, a mean field "tube model," to describe changes in elasticity observed in classical experimental studies of the mechanical properties of this type of network. In order to obtain a satisfactory comparison to the experiments, it was found to be necessary to account for the independently observed tendency of the network junctions to become localized in the network with appreciable swelling, as well as the interchain interactions emphasized in previous discussions of the localization model. [ABSTRACT FROM AUTHOR]

Hydrogen with small molecule size under high pressure can permeate most materials, being a challenge for rubber sealing materials used in hydrogen storage. The volume expansion of rubber materials due to high-pressure hydrogen is an Important indicator of their degradation and failure. Here, both microscopic calculations and experimental investigations of the nitrile rubber were conducted to evaluate the relation between the structure features and the expansion performance. Three factors, the acrylonitrile amount, the chain length, and the crosslinking degree, were considered to impact on the expansion of the nitrile rubber. Current study indicates that the increasing of acrylonitrile amount can result in the reduction of the volume expansion, owing to the preferential interactions between hydrogen and the butadiene group of nitrile rubber. Both of the chain length and the crosslinking degree are positively proportional to the chain elongation and then the volume of the nitrile rubber. Especially, the amount of acrylonitrile was found to be a key factor for evaluating the expansion of nitrile rubber under high-pressure hydrogen. This study performs microscopic calculations and macroscopic experiments to investigate the expansion of nitrile rubber, which is expected to be used in designing the sealing rubber material for high-pressure hydrogen storage applications. Highlights * Acrylonitrile determines the expansion performance of NBR within highpressure hydrogen. * Short chain and low crosslinking density suppressed the expansion of NBR. * Evaluating the expansion of nitrile rubber exposed to high-pressure hydrogen. KEYWORDS high-pressure hydrogen, molecular dynamic calculation, NBR O-rings, volume expansion, 1 | INTRODUCTION Hydrogen as a fuel is a good candidate for meeting the rapidly growing demand for energy in an environmentally friendly way. (1-3) However, the low-volume energy density [...]

In this study, a new concept of the elastic constant ratio was introduced to derive an S-N base function, which has removed the requirement of the shear modulus to be measured in previous work, allowing much wider applications in fatigue prediction with significant reduction in the costs involved in conducting experiments and acceleration of the design process in industries. In this approach, the damage parameter was the effective tensile stress verified for both positive and negative R ratios (the ratio between the minimum stress and the maximum stress). Existing work only provided a general description of the criterion without detailed explicit equations, which does not provide sufficient clarity to the reader and could lead to variable fatigue life predictions. Here, detailed equations are introduced on the calculation procedure to allow accurate results to be obtained for fatigue assessment. The applicability of the approach was validated using two industrial components, that is, the Metacone spring and the bush spring. The maximum values of the damage parameter corresponded to the same failure locations observed in the experiments. The suggested S-N base function, correlated with different materials and failure cycles, could be applied in a fatigue design stage and failure analysis for rubber isolators. Highlights * For the first time, an elastic constant ratio is introduced on different rubbers. * There is no additional test required for the material constants to save cost. * The approach is experimentally validated on two industrial isolators. * Monitoring stiffness in tests cannot determine the crack initiation accurately. KEYWORDS effective tensile stress, failure criteria, rubber fatigue, rubber isolators, S- N base function, 1 | INTRODUCTION Rubber components have been widely applied to dynamic environments in industries with many years of service, such as trains, ships, and automobiles. To meet the durability requirements [...]

To regulate the comprehensive performance of ethylene‐propylene‐diene monomer (EPDM)‐based oil‐absorbing expandable rubber, a series of irradiated α‐olefin‐EPDM7001 rubbers (EOR7001‐X‐Y) are prepared. The influence of the carbon chain length and content of α‐olefins on the structure and properties of the rubber is systematically investigated. Results show that EOR7001‐X‐Y possesses a cross‐linked network structure, and its gel fraction decreases gradually with the increase in carbon chain length and content of α‐olefins. The incorporation of α‐octadecene successfully creates micro‐nanoscale porous structures within the rubber matrix, providing favorable conditions for oil absorption. The introduction of α‐olefins and changes in irradiation dose do not significantly affect the thermal stability of EPDM7001 rubber. The tensile strength slightly reduces, while elongation at break significantly increases, improving the deformation capability. EOR7001‐18‐20 demonstrates exceptional resistance to aging and withstands external forces even after oil absorption. This study supports the development of high‐performance oil‐absorbing expandable rubber. [ABSTRACT FROM AUTHOR]

Highlights Blends of natural rubber (NR)/chlorobutyl rubber (CIIR) (50/50), along with their nanocomposites containing varying amounts of graphene nanoparticles (GNPs) with and without silane, were prepared using different feeding sequences and mixers. The results indicated that when GNP was first mixed with NR before adding CIIR, the highest GNP content was found in NR; the oxygen permeability and diffusion coefficient decreased significantly by 37% and 55%, respectively. Conversely, when graphene was initially added to CIIR, it was distributed in both rubbers and at the interface, enhancing phase interaction and achieving a finer morphology. This sample exhibited the greatest improvement in mechanical properties due to specific localization of GNP and increased crosslink density. Using an internal mixer instead of a two‐roll mill improved graphene dispersion, reduced curing time, and enhanced mechanical properties. Although the presence of silane reduced graphene dispersion, it improved mechanical and barrier properties due to increased crosslink density. Oxygen permeability was reduced by up to 36% at 3 phr of GNP content with silane. This research proves that the mixing order and the type of mixing equipment are crucial in determining the final performance of rubber composites, as they significantly influence the dispersion and localization of fillers. NR/CIIR/GNP nanocomposites were prepared by different methods and evaluated. Adding NR/GNP to CIIR led to more presence of GNP in NR and lower permeability. By adding CIIR/GNP to NR, GNP were placed more at interface, modulus improved. Mixing in an internal mixer improved GNP dispersion compared to a two‐roll mill. Silane improved mechanical and barrier properties of NR/CIIR/GNP nanocomposite. [ABSTRACT FROM AUTHOR]

Bio‐based elastomers and composites are of great interest in numerous applications for environmental sustainability. In this study, bio‐based elastomers with low hysteresis are developed from epoxied soybean oil (ESO) with tetradecanedioic acid (TA) as the curing agent. The as‐prepared ESO/TA thermosets are in the rubbery state at room temperature, with a glass transition temperature (Tg) falling between −19°C and −27°C depending on the amount of TA. With optimized amounts of TA, the elongation at break of ESO/TA thermosets exceeds 130%. ESO/TA thermosets display a stress‐softening behavior and remarkable resilience with low residual strain (<1%) and hysteresis (<7%) after removal of irregular crosslinks and/or interactions by the first stretching. The adhesion of ESO/TA thermosets to wood is also examined through adjustments to the pressure and temperature that are applied for curing. ESO/TA thermosets are then used as the matrix to prepare wood‐polymer composites. Their flexural properties are explored to demonstrate the potential for using ESO/TA thermosets in eco‐friendly wood‐polymer composites. [ABSTRACT FROM AUTHOR]

Aiming at the problem that lightweight algorithm models are difficult to accurately detect and locate tapping surfaces and tapping key points in complex rubber forest environments, this paper proposes an improved YOLOv8n-IRP model based on the YOLOv8n-Pose. First, the receptive field attention mechanism is introduced into the backbone network to enhance the feature extraction ability of the tapping surface. Secondly, the AFPN structure is used to reduce the loss and degradation of the low-level and high-level feature information. Finally, this paper designs a dual-branch key point detection head to improve the screening ability of key point features in the tapping surface. In the detection performance comparison experiment, the YOLOv8n-IRP improves the D_mAP50 and P_mAP50 by 1.4% and 2.3%, respectively, over the original model while achieving an average detection success rate of 87% in the variable illumination test, which demonstrates enhanced robustness. In the positioning performance comparison experiment, the YOLOv8n-IRP achieves an overall better localization performance than YOLOv8n-Pose and YOLOv5n-Pose, realizing an average Euclidean distance error of less than 40 pixels. In summary, YOLOv8n-IRP shows excellent detection and positioning performance, which not only provides a new method for the key point localization of the rubber-tapping robot but also provides technical support for the unmanned rubber-tapping operation of the intelligent rubber-tapping robot. [ABSTRACT FROM AUTHOR]

The application of polymer blends such as epoxidized natural rubber (ENR) and polyvinyl chloride (PVC) in immobilizing titanium dioxide (TiO2) photocatalysts has enticed many researchers. However, the presence of polymer limits the photocatalytic activity by hindering the surface‐active site of the immobilized TiO2. In this study, photoetching treatment with the presence of dye was successfully applied on the immobilized TiO2/ENR/PVC (TEP) to enhance the photocatalytic and photoelectrochemical (PEC) performance. Priorly, a dip coating technique was used to immobilize the TEP. The dye photoetching treatment was performed for several cycles to determine the reusability of the immobilized TEP. Furthermore, it demonstrated a significant enhancement of photocatalytic activity at which the best performance with the pseudo‐first‐order rate constant, k value of 0.1483 min−1 at the 13th cycle. The nonetched, photoetched TEP without dye and dye photoetched TEP have been characterized by scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), X‐ray diffraction (XRD), thermal gravimetric analysis (TGA), and PEC. It is believed that the dye photoetched TEP will produce a good photocatalytic activity and PEC performance due to the presence of dye stimulant during the photoetching treatment. [ABSTRACT FROM AUTHOR]

In this work, we prepare epoxidized aramid pulp (AP) by grafting ethylene glycol diglycidyl ether (EGDE) onto the surface of AP via poly catechol/polyamine (PCPA). Subsequently, we premix the epoxidized AP with carboxylated nitrile butadiene rubber (XNBR) to induce a chemical reaction with the carboxyl group in XNBR. The carboxylated nitrile butadiene rubber/cis‐polybutadiene rubber/aramid pulp (XNBR/BR/AP) composites are prepared by mechanical blending. Water contact angle, FTIR, and XPS confirm the grafting of EGDE onto AP via an epoxy group ring‐opening reaction. The rheological performance results indicate that the addition of EGDE decreases the curing time of the composites and increases the degree of cross‐linking of the composites. The compatibility between AP and rubber is analyzed by SEM, and it is deduced that the interfacial bonding between AP and composite is enhanced by EGDE. The tensile strength, tear strength, abrasion resistance, and solvent resistance of the composites are significantly improved after EGDE modification. RPA results show that the modified AP is uniformly dispersed in the composites and reduces the rolling resistance of the composites. A new and effective strategy is provided for the surface functionalization of aramid pulp meal, which has a wide range of rubber industry applications. Highlights: Composite mechanical properties increase with increasing EGDE content.Rheological properties of composites improved by EGDE incorporation.EGDE improves filler dispersion, reduced rolling resistance of composites.Increased interfacial bonding between AP and rubber due to EGDE. [ABSTRACT FROM AUTHOR]

Through anionic two‐stage polymerization, block‐type styrene‐butadiene rubber (SSBR) with systematically regulable low‐temperature loss peaks is successfully prepared. The influence of 1,2‐Bd unit in the soft segment of block‐type SSBR on mechanical properties, dynamic mechanical properties, and microscopic morphology is studied, while pressure factors are introduced into dynamic mechanical studies. The block‐type SSBR with a soft segment containing 21.9 wt% of 1,2‐Bd exhibits the highest tensile strength, elongation at break, and tear strength. Under atmospheric pressure, the soft segment 1,2‐Bd unit influences the dynamic mechanical properties by altering the chain segment's motion loss capability. As the mass fraction of 1,2‐Bd increases from 21.9 to 58.6 wt%, tanδmax increases, the glass transition temperature of the soft segment increases from −59.0 to −18.9°C. Additionally, influenced by thermodynamic compatibility, the microscopic morphology transitions from strong separation to weak separation. Pressure affects dynamic mechanical properties by altering the free volume of the chain segments. Pressure reduces tanδmax, increases Tg, and raises the average Tg of the soft segment by 11°C. The K value of the linear equation representing the relationship between the soft segment Tg and the mass fraction of 1,2‐Bd is unaffected by pressure. [ABSTRACT FROM AUTHOR]

This study investigates the novel effect of poly(lactic acid) (PLA) optical purity on PLA/liquid natural rubber (LNR) blend films fabricated by solution casting. An investigation was conducted to examine how different levels of PLA optical purity affect the mechanical, structural, morphological, thermal, and barrier properties of PLA/LNR films. Infrared spectroscopy analysis revealed that the D‐isomer content of PLA significantly affected the chemical interactions between the LNR and PLA. The favorable chemical interaction between the LNR and PLA with a high D‐isomer content also increased the elongation at break by 300%. Morphological investigations proved that the chemical interaction also improved the dispersion and reduced the size of the LNR droplets formed in the PLA matrix. Notably, while low D‐isomer PLA blends showed decreased crystallinity (Xc) upon LNR addition, high D‐isomer PLA blends exhibited increased Xc by 460%, leading to a 42% increase in oxygen transmission rate. Additionally, hydrolytic degradation of high D‐isomer PLA increased by 259% with increasing LNR content. Overall, optical purity of PLA plays an important role in determining the properties of PLA blends. [ABSTRACT FROM AUTHOR]

In order to improve the flame retardancy and smoke suppression of silicone rubber foam (SRF), the CoFe‐LDH was fabricated by coprecipitation method and used as flame‐retardant ingredient in SRF. The influence of CoFe‐LDH on the flame retardancy, combustion behavior, and thermal stability of SRF was investigated. The results demonstrate that SRF containing only 1.0 phr CoFe‐LDH can pass V‐0 rating in the vertical combustion test, with a limiting oxygen index of 28.6%. The total heat release and total smoke production are 22.2% and 61.1% lower than that of SRF, respectively. Moreover, CoFe‐LDH can improve the thermal stability of SRF in the high temperature range, and the char residue at 900°C of SRF/LDH composite is obviously higher than that of pure SRF. In addition, to further understand the flame‐retardant mechanism of CoFe‐LDH, the micromorphology of the char residue and the gaseous products during heating for SRF and SRF/LDH composite were analyzed. The results indicate that CoFe‐LDH exhibits excellent flame‐retardant effects in both condensed and gaseous phases for its functions of catalysis, carbonization, and nonflammable gas release. This study provides a more efficient and convenient strategy for the flame retardant and smoke suppression research of SRF. [ABSTRACT FROM AUTHOR]

The increase in demand for natural rubber has led to the search for alternative sources. Lactuca serriola is emerging as a promising candidate, as the quality of the natural rubber it produces is comparable to that of the Pará Rubber Plant, Hevea brasiliensis. This study examines the effect of methyl jasmonate (MeJA), a known elicitor, on the expression of key rubber biosynthesis pathway genes (HMGR1, HMGS1, CPT2, and SRPP1) in the latex of L. serriola plants. The expression levels of these genes increased significantly after the foliar application of 200 and 400 µM MeJA. The highest relative expression level for HMGR1, HMGS1, CPT2 and SRPP1 was 3.74, 18.56, 11.91and 16.59 fold respectively. Furthermore, the rubber content in L. serriola showed a significant rise post-treatment compared to the control with increasing the level of MeJA (6.19%, 7.24% and 7.85% which correspond to 0, 200 and 400 µM). Gel permeation chromatography revealed an augmentation in the molecular weight of extracted natural rubber from treated plants. Samples treated with 400 µM of MeJA had the highest molecular weight (1570 kg mol−1) compared to control (1186 kg mol−1). This study has demonstrated that MeJA, through the regulation of rubber biosynthesis genes, is capable of enhancing the quality and quantity of natural rubber extracted from alternative sources, such as L. serriola. [ABSTRACT FROM AUTHOR]

Water-based coating has gained much attention globally due to environmental issues. This work aims to develop a waterborne epoxy coating incorporated with modified natural rubber (NR) latex for improved performance. For this purpose, the NR latex was modified into three types of low molecular weight epoxidized natural rubber (LENR) latex. The waterborne epoxy resin was prepared by simply mixing the epoxy resin with an amine curing agent in water and various LENR latex contents (10 to 50 wt%). The waterborne epoxy/LENR blend was coated on a tin substrate and the cured coating demonstrated better adhesion and bending properties than the neat epoxy. Phase morphological properties displayed a rough surface with a heterogeneous surface structure of the dispersed rubber and epoxy matrix. Two glass transition temperatures were observed, corresponding to the rubber modifier and the epoxy matrix. The mechanical properties of the thermosetting epoxy/LENR blends were assessed, revealing a maximum increment in elongation ability by approximately 370% for adding 50 wt% LENR, compared to the neat epoxy. These results hold the potential avenue for utilizing NR-based material in the waterborne epoxy-based resin for coating applications. Furthermore, it contributes to the NR, a renewable and eco-friendly material, in the coating technology, embracing a sustainable future. [ABSTRACT FROM AUTHOR]

In this study, a novel biodegradable polymer electrolyte membrane with reduced fuel crossover, high selectivity, and high conductivity compared with Nafion 117 membrane in direct ethanol fuel cells (DEFCs) has been reported. Herein, polyvinyl alcohol/epoxidized natural rubber (PVA/ENR) blend membranes were synthesized via a simple solution casting method and applied in DEFCs. The structural and physicochemical features of the PVA/ENR blend membranes were examined using FESEM, FTIR, XRD, water absorption, ethanol uptake, swelling ratio and oxidative stability. ENR enhances the chemical, structural, and mechanical characteristics of PVA, making it a valuable material in fuel cell applications. The incorporation of ENR into the PVA matrix results in a compact morphology, excessive multifunctional groups, low fuel crossover, and high selectivity. The optimum membrane thickness achieves the highest selectivity, reaching up to 12.32 × 104 S s cm−3 at 30°C. Additionally, the maximum power density achieved is 19.52 mW cm−2, surpassing that of the Nafion membrane, which is only 14.55 mW cm−2 at 90°C. Furthermore, this biodegradable membrane can sustain operation for 1000 h at 90°C, owing to its ability to maintain hydration for an extended period. This study represents the first attempt to combine PVA and ENR in fuel cells. [ABSTRACT FROM AUTHOR]

Crosslinking natural rubber (NR) and styrene butadiene rubber (SBR) composites with carbon black (CB) have been utilized in the tire tread industry. A sulfur-based lightly crosslinker can potentially enhance the self-healing capabilities of rubber. Moreover, the rubber composites were studied for non-covalent interactions between the benzene rings of SBR and CB. In this research, rubber samples were prepared, and their structure was investigated using Fourier transform infrared (FTIR), and Raman spectroscopy. The red shift in Raman spectroscopy confirmed non-covalent interaction or hydrophobic interaction between SBR and CB in NR/SBR composites exposed to CB due to environmental change. The differential scanning calorimetry (DSC) thermograms showed that NR and SBR were incompatible. Additionally, the mechanical properties of these rubber blends were enhanced as the proportion of NR increased. The maximum self-healing performance reached 40% for the formulation containing 25 phr NR and 75 phr SBR, which also saved energy with low chain end movements. Therefore, these composites could be utilized as a semi-empirical model for studying crosslinked rubber blends, specifically in the rubber tire industry. [ABSTRACT FROM AUTHOR]

Since Charles Goodyear discovered the method of sulfur curing Natural Rubber in 1839, many studies have been carried out to understand its mechanism. Currently, the broadly accepted mechanism includes an activated accelerator complex formed by Zinc oxide, stearic acid, accelerators and sulfur. Furthermore, it is also broadly accepted that the coupling of the sulfur to the polymer takes place in the allylic position to the double bond. Modern passenger car tire treads no longer contain Natural Rubber but instead a blend of Solution Styrene Butadiene Rubber and Butadiene Rubber, filled with a silica/silane system. Is it possible to transfer all the gained knowledge from the Natural Rubber crosslink reaction to such modern passenger car tire tread formulations, or is it required to "re-think" sulfur curing? [ABSTRACT FROM AUTHOR]

The need for eco‐friendly cooling materials and material recycling are two urgent challenges to address. In this paper, the role of the ground tyre rubber treatment (cryo‐grinding and devulcanization) is investigated on the tensile and elastocaloric properties of Natural rubber (NR)/ ground tyre rubber (GTR). The GTR particles that are sieved (<63µm) and devulcanized by microwave irradiation (1 min at 800Watts) exhibit a low network chain density (0.53 × 10−4 mol.cm−3) resulting from crosslinks breakage and rubber chains scission, as supported by FTIR showing a decrease of S─S, C─S, and C─C bonds. The NR/GTR blends show a high elastocaloric effect as compared to the pristine NR, which can be ascribed to the high content of carbon black in the GTR (52 wt.%) and also the high level of devulcanization of the GTR. NR/GTR blends reach a heating of +8 °C and a cooling of >−6 °C, resulting in a material's coefficient of performance COPmat = 2.8–3 compared to 2.6 for the pristine NR. The concomitant effect of cryogrinding and microwave devulcanization is proposed as a way to improve the tensile and elastocaloric properties of natural rubber/waste rubber blends for their possible integration into elastocaloric devices for heating/cooling applications. [ABSTRACT FROM AUTHOR]

High-Content Crumb Rubber Asphalt (HCRA) binder improves road performance and address waste tyre pollution, yet its ageing behaviour is not fully understood. In this study, 70# neat asphalt binder and HCRA with rubber contents of 35% and 50% were selected and aged through the Thin Film Oven Test (TFOT) and Pressure Ageing Vessel (PAV) tests. FTIR (Fourier Transform Infrared Spectroscopy) and DSR (Dynamic Shear Rheometer) were employed to investigate their chemical composition and rheological properties. The FTIR results show that HCRA's chemical test results are similar to those of 70#, but HCRA is more susceptible to ageing. I(C=C) strength decreases with age. The DSR results show that HCRA outperforms 70# neat asphalt binder in terms of viscoelasticity, high temperature performance and fatigue resistance, and exhibits greater resistance to ageing. The ageing index (AI) was obtained through a calculation using the formula, and overall, 70# neat asphalt binder is more sensitive to ageing behaviour and less resistant to ageing, and HCRA is particularly outstanding for fatigue resistance. A strong correlation is observed between chemical composition and some rheological property indicators. Therefore, we are able to predict the rheological properties using chemical composition indicators. This study provides insight into the ageing behaviour of a neat asphalt binder and an HCRA binder and demonstrates that the HCRA binder outperforms conventional asphalt in several performance areas. It also provides theoretical support for the consumption of waste tyres to prepare high content crumb rubber asphalt. [ABSTRACT FROM AUTHOR]

In this study, epoxidized natural rubber (ENR) was mixed using a two-roller mixer. Water hyacinth fiber (WHF) acted as a reinforcing agent in the preparation of the rubber composite at 10 phr (ENRC/WHF). Chlorhexidine gluconate (CHG) was added at different concentrations (1, 5, 10, and 20 phr) as an antimicrobial and coupling agent. The tensile strength increased with a CHG content of 1 phr (4.59 MPa). The ENRC/WHF/CHG20 blend offered high hardness (38) and good morphology owing to the reduction in cavities and fiber pull-out from the rubber matrix. The swelling of the sample blends in oil and toluene decreased as the CHG content increased. Reactions of –NH2/epoxy groups and –NH2/–OH groups occurred during the preparation of the ENRC/WHF/CHG blend. The FTIR spectroscopy peak at 1730 cm−1 confirmed the reaction between the −NH2 groups of CHG and epoxy groups of ENR. The ENRC/WHF/CHG blend at 10 phr and 20 phr exhibited zones of inhibition against three bacterial species (Staphylococcus aureus, Escherichia coli, and Bacillus cereus). CHG simultaneously acted as a crosslinking agent between ENR and WHF and as an antimicrobial additive for the blends. CHG also improved the tensile strength, hardness, swelling, and antimicrobial properties of ENR composites. [ABSTRACT FROM AUTHOR]

We study the enhancement of the elastocaloric effect in natural rubber by using forced air convection to favour heat extraction during the elongation stage of a stretching–unstretching cycle. Elastocaloric performance is quantified by means of the adiabatic undercooling that occurs after fast removal of the stress, measured by infrared thermography. To ensure accuracy, spatial averaging on thermal maps of the sample surface is performed since undercooled samples display heterogeneities caused by various factors. The influence of the stretching velocity and the air velocity is analysed. The findings indicate that there is an optimal air velocity that maximises adiabatic undercooling, with stretching velocities needing to be high enough to enhance cooling power. Our experiments allowed the characterisation of the dependence of the Newton heat transfer coefficient on the air convection velocity, which revealed an enhancement up to 600% for air velocities around 4 m/s. [ABSTRACT FROM AUTHOR]

To reinforce natural rubber latex foam, fumed silica and precipitated silica are introduced into latex foam prepared using the Dunlop process as fillers. Four types of silica, including Aerosil 200 (hydrophilic fumed silica), Reolosil DM30, Aerosil R972 (hydrophobic fumed silica), and Sipernat 22S (precipitated silica), are investigated. The latex foam with added silica presents better mechanical and physical properties compared with the non-silica foam. The hydrophobic nature of the fumed silica has better dispersion in natural rubber compared to hydrophilic silica. The specific surface area of silica particles (BET) also significantly influences the properties of the latex foam, with larger specific surface areas resulting in better dispersity in the rubber matrix. It was observed that exceeding 2 phr led to difficulties in the foaming process (bulking). Furthermore, higher loading of silica also affected the rubber foam, resulting in an increased shrinkage percentage, hardness, compression set, and crosslink density. The crosslink density increased from 11.0 ± 0.2 mol/cm3 for non-silica rubber to 11.6 ± 0.6 mol/cm3 for Reolosil DM30. Reolosil DM30 also had the highest hardness, with a hardness value of 52.0 ± 2.1 IRHD, compared to 45.0 ± 1.3 IRHD for non-silica foam rubber and 48 ± 2.4 IRHD for hydrophilic fumed silica Aerosil 200. Hydrophobic fumed silica also had the highest ability to return to its original shape, with a recovery percentage of 88.0% ± 3.5% compared to the other fumed silica. Overall, hydrophobic fumed silica had better results than hydrophilic silica in both fumed and precipitated silica. [ABSTRACT FROM AUTHOR]

Over recent decades, numerous strong earthquakes have caused widespread devastation, including citywide destruction, significant loss of life, and severe structural damage. Seismic base isolation is a well-established method for mitigating earthquake-induced risks in buildings; however, its high cost often limits its implementation in developing countries. Simultaneously, the global rise in vehicle numbers has led to the accumulation of discarded tires, intensifying environmental challenges. In response to these issues, this study investigates the development of a seismic isolator matrix using recycled rubber from vehicle tires, proposed as a sustainable and cost-effective alternative. Ten recycled rubber matrices were experimentally evaluated for their physical and mechanical properties. The matrix with optimal granulometry and binder content, demonstrating superior performance, was identified. This optimized matrix underwent further validation through compression and cyclic shear tests on reduced-scale prototypes of fiber-reinforced isolators, which included five prototype designs, two of which featured flexible reinforcement. The best-performing prototype comprised a recycled rubber matrix with 15% binder and glass fiber, exhibiting vertical stiffness and damping characteristics superior to those of natural rubber. Specifically, this prototype achieved a damping ratio of up to 22%, surpassing the 10% minimum required for seismic isolation, along with a vertical stiffness of 45 kN/mm, critical for withstanding the vertical loads transferred by buildings. These findings suggest that the recycled tire rubber matrix, when combined with glass fiber, is a viable material for the production of seismic isolators. This combination utilizes discarded materials, contributing to environmental sustainability. [ABSTRACT FROM AUTHOR]

Proteins are important factors affecting the properties of natural rubber. Therefore, investigating the effect of free and bonded proteins on the structure and mechanical properties of the vulcanized crosslinking network of natural rubber would provide a theoretical basis for the production of high mechanical resistance natural rubber. Herein, natural rubbers with different protein contents and types were prepared by high-speed centrifugation. And, the effects on their network structure, vulcanization, tensile strength, tearing strength and dynamic mechanical properties were investigated. The results showed that the reduction in protein content led to the decrement in the entanglement networks, crosslinking density and tensile and tear strengths of the vulcanized natural rubber. Moreover, the bonded proteins had an obvious influence on the vulcanization process, while free proteins played an important role in the crosslink densities. These results reveal that both bonded and free proteins are involved in the vulcanization process and the construction of the vulcanized crosslinking network structure of natural rubber, which enhances the mechanical properties such as the modulus and tensile strength of vulcanized natural rubber. [ABSTRACT FROM AUTHOR]

The use of rubber crumbs provides a viable solution for alleviating the disposal problem of waste tires. In this study, rubberized sulfur concrete (RSC) was researched to investigate the optimal mixture proportion and to improve the mixing process in terms of compressive strength and durability performance. For the mixture of the RSC, sand, rubber particles, and micro-filler were adopted as aggregates and sulfur was used for the binding material. Moreover, two mixing processes were applied: the dry mixing process and the wet mixing process. Based on the test results, the increment of rubber particles in the mixture led to a decrease in the compressive strength for both the dry and wet mixing processes. To minimize the voids between the sand and rubber particles, the micro-filler was used at 5% of the total volume. The amount of sulfur varied slightly depending on the mixing process: 30% sulfur for the dry mixing process and 34% sulfur for the wet mixing process, respectively. Consequently, compared to the dry mixing process, the wet mixing process increased the bonding force between sulfur and rubber powder due to the simultaneous heating and combining. In toughness, the wet mixing process demonstrates a 40% higher energy absorption capability compared to the dry mixing process. For the durability performance of the RSC, the mixture with 20% rubber particles produced using the wet mixing process exhibited better corrosion and freeze–thaw resistance. [ABSTRACT FROM AUTHOR]

Dilatancy is commonly defined as the ratio of the rates of plastic volumetric strain to plastic deviatoric strain, denoted as Dp. Owing to the high modulus of elasticity, the elastic volumetric and deviatoric strain rates under shear stress in conventional cohesionless materials are negligible. Therefore, using the ratio of the rates of total volumetric to deviatoric strain (Dt) as an approximation is common in studying stress–dilatancy behavior and calibrating dilatancy model parameters. This approach is also common in the study of rubber-added cohesionless materials (RCM). However, RCM with a common range of rubber content exhibit a significantly lower modulus of elasticity compared to conventional cohesionless materials. Further research is needed to evaluate the potential impact of elastic strain rates in RCM on stress–dilatancy analysis. Therefore, comparisons were conducted on the stress–dilatancy responses of a series of tests on RCM, where dilatancy is calculated by Dp and Dt, respectively. Furthermore, a modified method for calibrating the parameters of a state-dependent dilatancy model considering Dp is presented. It turns out that Dp is better suited and more precise for dilatancy analysis on highly elastic RCM. Additionally, the dilatancy model can more precisely capture the test results of RCM with parameters calibrated by the proposed method. [ABSTRACT FROM AUTHOR]

Year by year, more and more plastic is used worldwide. A large part of post-consumer waste is still stored in landfills instead of being reused. The solution to this problem may be recycled materials (recyclates) or biodegradable materials. The method of 3D printing, regarded as a clean processing technology, can significantly contribute to addressing global plastic pollution by utilizing post-consumer recycled polymers to create new components and parts. Therefore, this study focuses on the assessment of various properties and characteristics of 3D-printed compositions based on post-consumer polypropylene (PP) and rubber crumbs, recycled from packages foils and car tires, respectively. Moreover, within this study, we compared the mechanical performance of the injection molding material with the one obtained from 3D printing. A characterization was made considering the thermal and mechanical properties as well as the "print quality" through the microscopic and tomographic analysis of subsequent print passes, the number of free spaces, and imperfections in the polymer melt. Samples obtained using the FDM and injection methods exhibited comparable melting temperatures, while the samples obtained by injection molding exhibited slightly better mechanical performance, higher hardness, and impact strength. [ABSTRACT FROM AUTHOR]

Previous studies have shown that choices about how to configure stepping-stones to be used as playground or exercise equipment reflect a person's action capabilities. In two experiments, we investigated whether choices about how to configure stepping-stones to be used as a path for locomotion additionally reflect the goals for which or the constraints under which the path is to be used. In Experiment 1, participants created stepping-stone configurations (with rubber mats) that would allow them to cross a given space quickly, comfortably, or carefully. Configurations in the "Quickly" condition consisted of fewer mats, and longer mean (linear) distances between mats, and greater "challenge" (relative to maximum stepping distance) than in the other two conditions. In Experiment 2, participants created stepping-stone configurations that would be fun to use or that would be easy to use to cross a given space. Configurations in the "Fun" condition consisted of more mats, longer linear distances between mats, and greater "challenge" than those in the "Easy" condition. Moreover, paths in the "Fun" condition were also wider, longer, and exhibited larger changes in distances and angles between consecutive mats than in the "Easy" condition. The results are discussed both in terms of implications for understanding affordances and for the design of stepping-stone paths. [ABSTRACT FROM AUTHOR]

This article aims to evaluate and compare two types of organic surface-modified-nanoclay of octadecylamine-modified-bentonite-nanoclay (ODA-BNC) and aminopropyltrimethoxysilane-octadecylamine-modified-nanomontmorillonite (APS-ODA-MMT). Each type of nanoclay is combined with silica as a bi-filler for natural rubber (NR)/ethylene propylene diene monomer rubber (EPDM) in a 50/50 blend ratio for possible vulcanized rubber nanocomposite application. The total filler content is 50 phr while nanoclay filler content ranges from 0 to 20 phr, keeping the other ingredients ratio fixed. The prepared composites are characterized by the Fourier transform infrared spectrophotometer (FTIR) and their mechanical and thermal properties are thoroughly investigated. The data reveal that the fillers added to the rubber can improve its surface properties according to their type and amount as confirmed by the Atomic force microscope (AFM), and Scanning electron microscope (SEM) investigation. The surface of rubber containing APS-ODA-MMT displayed higher height (251) and roughness surface (94.11), than those (69.8) and (45.62) respectively, containing ODA-BNC. Moreover, the acid resistance of the prepared composites is verified and indicated that increasing the nanoclay ratio (20%) enhances the acid resistance by reducing the surface distortion while keeping the surface morphology. The mechanical properties and Thermogravimetric Analysis (TGA) measurements showed that the rubber containing ODA-BNC has higher values of stress (2.2), elongation (975), and thermal stability (470, 505, 520°C) than those (1.75), (650), and (440, 460, 470°C) respectively, containing the APS-ODA-MMT. Moreover, the durability investigation of the vulcanized rubber via the AFM found the modified composites can be used in harsh environments as a covering layer in petrochemical networks or chemical factories. [ABSTRACT FROM AUTHOR]

Microplastic particles are emerging water-laden waste that cause a worrying concern towards the environment and humans health. Due to its small size and geometry, and uncertain surface properties, the microplastic waste capturing method in water is still evolving. To date, a number of findings report on the emergence of microplastic surface charging, especially when exposed to water environment. In this study, the natural rubber (NR) latex band was utilized to capture the microplastic waste via a surface capturing mechanism. The NR band was produced using a film casting and curing methods. The surface charging mechanism on the NR band was introduced via the usage of high amount of ZDEC accelerator and, periodic stretching and relaxation procedures. In this work, ZDEC was used as an accelerator for the rubber formulation, and surface charge booster for the NR band. The surface charge of the NR band generates electrostatic interaction with the microplastic waste in water. The polypropylene (PP) microplastic was captured via the surface attraction mechanism using the manufactured NR band. Based on FTIR analysis, the presence of PP microplastic can be quantified on the contaminated NR band surface. The NR band shows the improvement in tensile and tear properties and crosslink density, mainly due to high amount of ZDEC used. At ZDEC loading of 20 phr, the NR band recorded the highest surface potential value, and this is owing to the formation of Zn2+ complex ions on its surface. XRF analysis indicates that the increment of Zn content in the NR band with increasing ZDEC content, that suggests the formation of Zn2+ complex ions. [ABSTRACT FROM AUTHOR]

Elastomers have diverse properties that make them suitable for use in many industrial applications. Natural Rubber, in particular, is an attractive elastomer due to its desirable mechanical properties as well as lightweight compared to metals. However, due to the natural rubber structure, these elastomers are susceptible to heat, oxidation, and chemical compounds, which limits their potential use. In this paper, in order to study the behavior of natural rubber under thermo-oxidative aging, experiments, including continuous stress relaxation, creep, and intermittent tensile tests, are carried out on the samples. Based on the experimental results and using dynamic-network model, a mechanical-chemical-diffusion model is proposed to predict the changes in natural rubber properties during thermo-oxidative aging considering the effect of the natural rubber curing system. In the chemical part of the model, the two main process of aging, including chain scission and crosslinking, are modeled by using two internal variables. The proposed model is implemented using the finite element method to simulate experimental tests for the model verification. The comparisons demonstrate the proposed model ability to accurately simulate the various loading states under thermo-oxidative aging of natural rubber. [ABSTRACT FROM AUTHOR]

The rubber joints mounted on swing arms provide the main part of the yaw stiffness for wheelsets and thus have a significant influence on the dynamic behaviour of railway vehicles. However, their nonlinear dynamic properties concerning the frequency, amplitude, and temperature were not fully considered in previous studies, most of which adopt simple models such as the Kelvin–Voigt model to represent rubber components. This study aims to investigate the radial nonlinear properties of swing arm rubber joints under various conditions and assess their effects on the dynamic performance of high-speed trains. A nonlinear rubber spring model which combines the fractional derivative Zener model with Berg's friction model is established. To achieve a better fit to the measurements of a swing arm rubber joint, an optimisation-based method is employed to identify the model parameters. The viscous and frictional effects of the rubber joint are compared at different frequencies, amplitudes, and temperatures, by determining the predominant element of the nonlinear model. Additionally, the nonlinear rubber spring model is integrated into a high-speed vehicle dynamic model to investigate the effects of the nonlinear properties of swing arm rubber joints on the vehicle dynamic behaviour through the MATLAB/SIMPACK co-simulation method. [ABSTRACT FROM AUTHOR]

This paper analyzes whether the rubber stack traction structure can be applied to 140 km/h metro vehicles from the perspective of vehicle dynamics. The rolling vibration test results indicate that the vehicle Ride Index exceeds the standard limit, the low-frequency vibration of the car body is significantly greater than that of the frame and axle box, and the lateral motion mode of the car body reaches 2.0 Hz. Through the stiffness test, it is found that when the displacement is less than 5.93 mm, the additional stiffness of the rubber stack traction structure exceeds 0.55 MN/m, which is far greater than the stiffness exhibited by the Z-shaped traction rod at the same displacement. The simulation results demonstrate that the excessive additional stiffness of the traction rubber stack is the primary factor for the car body abnormal vibration and does not effectively improve the vehicle stability. It is recommended that this type of metro shall use a rubber stack traction structure with small additional stiffness or Z-shaped traction rod to improve the car body vibration characteristics at 140 km/h. Furthermore, the recommended maximum operating speed for the bogie with the studied rubber stack traction structure is 80 km/h. [ABSTRACT FROM AUTHOR]

Elastomeric products in service condition undergoe thermo-oxidative degradation under the influence of temperature, oxygen, ozone etc. Tyre is one such product where ageing phenomena affect its performance properties as it is subjected to various temperature and environmental conditions during its service life. However, ageing is a complex process and depends on many factors that include rubber type, temperature, stress level, etc. To study the underlying mechanism and kinetics of such intriguing phenomenon, a Natural Rubber based compound was chosen in the present work. The rubber compound was subjected to an aerobic ageing at a fixed temperature of 70 °C and the effect of prolonged ageing time (1 week, 2 weeks, 4 weeks, and 8 weeks) on key performance properties such as, mechanical, dynamic mechanical and fatigue crack growth resistance was evaluated. Fatigue crack growth (FCG) studies were conducted to understand the degradation of crack growth resistance with respect to ageing. The morphology of the fractured surface was also captured by Field Emission Scanning Electron Microscope to reveal the nature of fracture failure. The static as well as dynamic modulus of aged compound was found to be significantly increased with increase in ageing time which was an indication of enhanced cross-linking density. This enhanced stiffness leads to deterioration of the fatigue resistance property and as a result FCG rate increased with ageing time. The samples were characterized by Fourier transform infrared spectroscopy to understand the changes in chemical structure during ageing which revealed that intensity of double bond content was reduced by increasing ageing time. Apparent cross-linking density and other relevant chemical analysis were also performed to establish the proposed mechanism. [ABSTRACT FROM AUTHOR]

Particle shape and grain-scale deformability play key roles in controlling the response of granular material; however, in the literature, the effects of these parameters have generally been evaluated separately. In this context, this study attempts to investigate the coupled effects of these parameters on the repose angle of the sand–rubber mixture using the discrete-element method. For this purpose, the realistic shapes of three different sands and two different rubbers were reflected in the simulations. The grain-scale deformability of rubber particles was modeled by connecting the ball-cluster structure with the linear parallel bond contact model. In addition, to clearly distinguish the role of deformability in the response, the rubber particles were simulated also using a rigid clump model. The parameters of the model were validated using different tests for grain and sample scales. A series of numerical analyses were conducted, and repose angles were determined using image processing techniques. The variation of repose angle was correlated with porosity in the sample scale. The contribution of interparticle friction and interlocking mechanism on the repose angle was revealed using the coordination number and anisotropy coefficient of the contacts in the microscale. The results show that the angle of repose increases with increasing irregularity of the particles. Even though the interlocking mechanism is weakened by the addition of soft rubber, there is an increase in the repose angle of the mixtures thanks to the superior interparticle friction properties of the rubber particles. The results indicate that a high repose angle can be constituted by controlling the particle shape and deformability parameters. [ABSTRACT FROM AUTHOR]

Epoxidized natural rubber with 50 mol% epoxide (ENR-50) was compounded with zinc chloride (ZnCl2) and subjected to torque response analysis using a moving die rheometer. It was found that different ZnCl2 concentrations (3, 5, 7, 9, and 12 millimoles (mmol)) mixed in ENR-50 exhibited positive torque responses, prompting further molecular characterization using Fourier transform infrared spectroscopy. The results indicated distinct absorption peaks at wavenumbers of 442 and 809 cm-1, which signify the presence of -O-Zn-O-coordination linkages. The curing characteristics of ENR and ZnCl2 compounds showed that increasing ZnCl2 content resulted in higher minimum and maximum torque values, but also led to a decrease in scorch time and cure rate index (CRI). Moreover, higher ZnCl2 concentrations enhanced the strength properties (tensile strength, moduli, stiffness, toughness, and hardness), crosslink densities, dynamic shear moduli, initial modulus during relaxation experiments, and thermal resistance, as evidenced by temperature scanning stress relaxation (TSSR), thermogravimetric analysis, and dynamic mechanical analysis. However, an increase in ZnCl2 content led to a reduction in elongation at break due to the higher crosslink density within the coordination networks in the ENR matrix, which resulted in the movement constraint of the rubber vulcanizate. [ABSTRACT FROM AUTHOR]

Natural rubber (NR) composites reinforced with sepiolite and crosslinked with phenolic resin were prepared. Effects of compatibilizer types and contents, namely 3-aminopropyl triethoxysilane (APTES) or epoxidized NR (ENR50), on curing, tensile, strain-induced crystallization, and stress relaxation were investigated. Compared to APTES, ENR50 provided a greater compatibilizing effect in the NR composites. The ENR50 introduced strong physical and chemical interactions between sepiolite and NR, while only physical interaction was present in the APTES compatibilized composites. Stronger interaction between rubber and sepiolite improved filler dispersion, swelling resistance, and tensile strength; and delayed stress relaxation of the composite. Increased addition of ENR50 improved the modulus and tensile strength, and the greatest tensile strength was achieved at 2 phr ENR50 with a 15% improvement over composite without compatibilizer. In the case of APTES, 2 phr level enhanced tensile strength, but a further increase in APTES content degraded tensile, swelling resistance, and stress relaxation responses, due to its plasticizing effect. Moreover, ENR50 enhanced the strain-induced crystallization and delayed stress relaxation of the composites more than APTES. Weaker interaction between rubber and filler in APTES filled composites was due to having only hydrogen bonds formed between rubber and filler, in addition to crosslinks. [ABSTRACT FROM AUTHOR]

Research into sustainable packaging materials has gained increasing importance due to the pressing environmental concerns related to plastic waste. The present study focused on developing a sustainable paper coating based on modified natural rubber (NR) latex filled with gelatin (GT). The graft copolymer latex of NR and poly(vinylbenzyl chloride) bearing quaternary ammonium groups, abbreviated as NR-g-QPVBC, was first synthesized. GT was then incorporated into the latex, and the combination of these materials resulted in a heat-sealable film with good tensile properties and a water barrier. The ionic crosslinking of the latex film was achieved by the reaction with ethylenediaminetetraacetic acid (EDTA). Heat-sealing studies of the NR-g-QPVBC latex film filled with GT (NR-g-QPVBC/GT) revealed its heat-sealability at 160 °C. Scanning electron microscope (SEM) analysis further confirmed the diffusion of the chains across the interface during heat sealing. Dip coating was a method for depositing latex film on kraft paper. The paper coated with the NR-g-QPVBC/GT latex showed a significant increase in dry and wet-tensile strength compared to the uncoated paper. The sealing process was optimized to achieve a heat-seal strength of 755.31 N/m at a dwell time of 3 s and a temperature of 160 °C. The research's practical application was demonstrated by transforming the coated paper into various heat-sealable bags using a handheld bag sealer. [ABSTRACT FROM AUTHOR]

The waste management sector is crucial for protecting the environment, conserving resources, and promoting sustainable development by ensuring efficient disposal, recycling, and minimizing the harmful impact of waste. This study aims to understand the performance levels (compressive strength), environmental impact, and overall sustainability of three concrete mixes, two of which use recycled materials. The mixes are defined as a conventional mix, mix one, which replaces dune sand for recycled rubber in the mix design, and mix two, which utilizes recycled aggregate as a replacement for fine aggregates. SEM-EDS is used to assess the elemental composition and surface morphology of the materials. The potential leaching of pollutants such as polycyclic aromatic hydrocarbons (PAHs), non-targeted organic compounds, and heavy metals was obtained using GC/MS and ICP-OES. The results showed low concentrations of PAHs in all mixes and a low calculated Potential Ecological Risk Index (PERI), where the conventional mix and mix two had the lowest risk (55 and 33, respectively) compared to mix one, which displayed a higher risk of 125. The results of the heavy metals assessment yielded that mix one was the most contaminated, with 1535 mg/kg of nickel and 1200 mg/kg of zinc, followed by the conventional mix, with 1385 mg/kg of nickel and 135.5 mg/kg of chromium, and finally, mix two was the least contaminated with 378.5 mg/kg of nickel and 142.5 mg/kg of zinc. Overall, the sustainability potential showed that mix two, with the recycled aggregates, was the most sustainable, with a Building Material Sustainability Potential (BMSP) value of 9.25. The study advocates for a shift toward sustainable concrete practices to mitigate environmental impacts while maintaining structural integrity. [ABSTRACT FROM AUTHOR]

To address the environmental impact of greenhouse gases in cement production, incorporating cement substitute materials is crucial. However, the slow degradation of discarded tires poses environmental challenges, making burial or incineration unsustainable. This study explores the integration of discarded tires as crumb rubber in concrete and the use of silica fume as a cement substitute. Experimental methods, coupled with neurofuzzy systems, were employed to predict the mechanical properties of the resulting modified concretes. In the experimental approach, silica fume replaced cement at weight percentages of 0%, 10%, 12%, and 15%, while crumb rubber substituted sand at volume percentages of 0%, 10%, and 25%. Compressive and flexural strengths were evaluated at seven, 28, and 90 days, with tensile strength assessed at 28 days. The neurofuzzy system utilized six inputs—cement, gravel, sand, silica fume, water–cement ratio, and sample age—to forecast tensile and compressive strength in silica fume-containing concrete. Similarly, six inputs—cement, gravel, sand, crumb rubber, water–cement ratio, and sample age—were used to predict flexural and compressive strength in rubber-containing concrete. The findings reveal that the inclusion of silica fume enhances the mechanical properties of concrete, while the introduction of crumb rubber diminishes these properties. Specifically, a quantitative analysis demonstrates the positive impact of silica fume on the strength and contrasting effect of crumb rubber. The neurofuzzy system exhibits remarkable accuracy in predicting tensile and compressive strength for silica fume-containing concrete and flexural and compressive strength for rubber-containing concrete. [ABSTRACT FROM AUTHOR]

Accelerated degradation tests (ADTs) have been widely adopted for products whose failure is defined as the first-passage-time (FPT) when the degradation path crosses a given threshold. However, for products whose failure is defined as the last-exit-time (LET), few studies related to ADT have been investigated. In this paper, we focus on designing an optimum test condition setting and sample allocation scheme for ADTs under the LET failure mode. In particular, the widely adopted Wiener process model and the generalized exponential acceleration model are used to describe the fluctuating degradation behaviors of products. By minimizing the asymptotic variance of mean-time-to-failure under the normal use condition, we design a two-level optimum test plan and a three-level compromise plan under the constraints of total sample size and stress region. The optimum plans are given in analytical forms, and we prove that the optimum plans under the FPT failure mode and LET failure mode are equivalent under some situations. Finally, a renewed selection method for the upper limit of the stress level in ADTs is proposed based on the prior ADT information from the perspective of accelerated mechanism equivalence. The proposed method is illustrated using a real-world application to rubber rings. [ABSTRACT FROM AUTHOR]

The attenuation of impact inducer vibration is critical to the safety of underground protection structure, equipment and personnel. Metamaterials and metastructures show great potential in terms of sound and impact attenuation. To effectively attenuate ground shock-induced vibration of underground protective structures, scaled shallow-buried annular metastructures with concrete–rubber layered structures were proposed and constructed. Underground explosion experiments were performed to investigate the vibration attenuation effect of annular metastructures with different layered structures. It is clear in this research only annular metastructures with concrete–rubber–concrete structures like annular metastructure model B6 have the most excellent wave attenuation performances, whose rubber layer thickness must be over 6 mm and hardness is 20 HA. Other layered structures with rubber layer thickness of 0.3 cm or with more layers cannot effectively attenuate the shock wave in this research. [ABSTRACT FROM AUTHOR]

This study explores the impact of a graphene oxide (GO)/nano silica (NS) hybrid (GO/NS) filler on the diffusion characteristics of natural rubber (NR) composites when exposed to toluene, xylene, and hexane solvents. The lowest solvent uptake is observed for NR GO/NS 3 (3 phr), which is attributed to forming a robust filler network within the composite. The calculation of crosslink density using the Flory‐Rehner equation reveals significantly higher values for NR GO/NS 3, indicating good crosslinking density in the presence of the hybrid filler. Furthermore, molecular mass between crosslinks (Mc) is calculated, demonstrating a favorable fit with the Affine model. The investigation extends to theoretical modeling, where the Korsemeyer–Peppas and Peppas–Sahlin models are employed to predict solvent uptake behavior. Strikingly, the experimental values exhibit a strong alignment with the Peppas–Sahlin model. This comprehensive analysis provides valuable insights into the diffusion behavior of graphene oxide/nano silica (GO/NS) hybrid‐reinforced natural rubber latex in organic solvents, highlighting potential applications in areas such as solvent‐resistant coatings, barrier materials for chemical storage, and enhanced performance in protective gloves and seals used in harsh chemical environments. [ABSTRACT FROM AUTHOR]

Translation abstract Investigating natural rubber latex (NRL) composites through compressive testing for renewable and sustainable building materialsThis article explores the innovative use of natural rubber latex (NRL) as a fundamental component in the development of sustainable and renewable composite building materials, particularly focusing on incorporating wood chips as reinforcing particles. The study investigates the compressive mechanical properties of various composite formulations, analysing the influence of NRL contents and particle types – considering different wood species, shapes and sizes. Key factors such as particle geometry, NRL content, and sample preparation methods are identified as crucial factors in enhancing the mechanical properties of these composites. The results show that NRL composites exhibit distinctive characteristics like non‐linear behaviour, hysteresis, stress relaxation, and the Mullins effect during compression tests. The significance of these composite materials in construction is heightened by their potential to utilize NRL sourced from plants other than rubber trees, such as dandelions, thus advancing sustainable construction practices. This research aims to focus attention on exploring new, flexible, and highly customized composite materials by utilizing natural fibres and NRL across a range of construction applications. [ABSTRACT FROM AUTHOR]

ABSTRACT This study systematically investigates the small‐strain stiffness of sand‐rubber mixtures, focusing on combined particle disparity—both larger sand with smaller rubber and smaller sand with larger rubber—using the discrete element method. The effectiveness of various state variables in capturing stiffness behavior across different rubber contents and size disparities (SDs) is evaluated. Conventional state variables developed for natural sands, such as void ratio and mechanical void ratio were found to be less effective in describing the small‐strain stiffness characteristics of sand‐rubber mixtures due to distinct properties of rubber. This study then demonstrates that the stiffness contribution of rubber materials could be negligible, emphasizing that particle property disparity is more significant than SD between sand and rubber materials. Therefore, an adapted state variable, considering only active sand particles, shows improved performance for capturing the correlation between small‐strain stiffness with increasing rubber contents, suggesting its potential utility over conventional variables. Additionally, a refined void ratio, including inactive sand particles but excluding rubber, offers a practical alternative for capturing small‐strain stiffness in experimental and engineering practices, aligning with previous experimental observations. These findings underscore the need for developing more effective state variables that accurately reflect the interactions within heterogeneous materials like sand‐rubber mixtures. [ABSTRACT FROM AUTHOR]

Coarse-grained molecular dynamics (CGMD) simulations were employed to investigate the effects of phospholipids on the aggregation of hydrophilic, modified carbon-nanoparticle fillers in cis-polyisoprene (cis-PI) composites. The MARTINI force field was applied to model dipalmitoylphosphatidylcholine (DPPC) lipids and hydrophilic modified fullerenes (HMFs). The simulations of DPPC in cis-PI composites show that the DPPC lipids self-assemble to form a reverse micelle in a rubber matrix. Moreover, HMF molecules readily aggregate into a cluster, in agreement with the previous studies. Interestingly, the mixture of the DPPC and HMF in the rubber matrix shows a cluster of HMF is encapsulated inside the DPPC reverse micelle. The HMF encapsulated micelles disperse well in the rubber matrix, and their sizes are dependent on the lipid concentration. Mechanical and thermal properties of the composites were analyzed by calculating the diffusion coefficients (D), bulk modulus (κ), and glass transition temperatures (Tg). The results suggest that DPPC acts as a plasticizer and enhances the flexibility of the HMF-DPPC rubber composites. These findings provide valuable insights into the design and process of high-performance rubber composites, offering improved mechanical and thermal properties for various applications. [ABSTRACT FROM AUTHOR]