Search Results (90)

Polymer composites are of considerable interest due to the possibility of improving the performance parameters of plastics. The filler is a component whose introduction into the rubber mixture can affect the physicochemical and functional properties of the composite. It is present in the largest quantity in the mixture, so its type is of significant importance in the polymer composite production process. Currently, much attention is being paid to the potential use of various materials as fillers to improve the properties of composites. These materials should, among other things, exhibit good adhesion to the polymer matrix and a high degree of dispersion. One example of such a material is dried plant material. In this group, dried leaves of two plants—sage (Salvia officinalis) and lucerne (Medicago sativa)—were introduced into a rubber mixture in several different content variants. The mixtures were subjected to durability and aging tests and the results were compared with a mixture without any plant additives. Of all the test variants with plant filler, the best results were obtained with the lowest proportion of dried plant material, which was 5 Parts per Hundred Rubber (PHR). In this case, most parameters remained at a level similar to the variant without additives. A slight improvement was observed in elongation at break for the mixture with sage (from 550% to 559%), while in the case of the mixture with lucerne, the color improved (from 1.21 to 0.94). Some parameters of vulcanization characteristics and tensile strength deteriorated. For the latter parameter, a decrease of 11% was noted for the mixture with sage (from 4.65 MPa to 4.13 MPa) and 18% for the mixture with lucerne (to 3.82 MPa). Interestingly, as a result of the ageing of the samples, a significant part of the mixtures with dried plants obtained better results in the case of tensile strength than before ageing. This applies especially to the following variants: 30 PHR for the mixture with sage (an increase of 48%) and 5 PHR for the mixture with alfalfa (an increase of 15%). In general, it should be noted that the functional parameters deteriorated with the increase in the proportion of plant additives. Full article

Natural rubber is a widely used biological polymer material because of its excellent comprehensive performance. Nevertheless, the performance of domestic natural rubber cannot meet the requirements for high-end products such as aviation tires, which has become a constraint on the innovation and upgrading of high-end manufacturing enterprises and the enhancement of global competitiveness in China. To solve the bottleneck problem of natural rubber processing technology, this study systematically analyzed the effects of different varieties of fresh latex ratios on the processing and dynamic properties of bio-coagulated natural rubber. By mixing PR107 and Reyan72059 fresh latex with Reyan73397 fresh latex according to proportion, the fresh latex was coagulated by enzyme-assisted microbials, and the effects of the fresh latex ratio on physical and chemical indexes, molecular weight distribution, vulcanization characteristics, processing properties, cross-link density and physical and mechanical properties of the natural rubber were analyzed. The results showed that the aging resistance of natural rubber coagulated with enzyme-assisted microbial decreased, and the aging resistance of natural rubber increased with the increase in the mixing ratio of PR107 and Reyan72059 fresh latex. The proportion of high molecular weight of the natural rubber coagulated with the enzyme-assisted microbial increased, and the fresh latex mixing had little effect on the molecular weight distribution curve. Under the carbon black formulation, the CRI of the enzyme-assisted microbial coagulated natural rubber compound was relatively larger. Under the same strain conditions, the H-3 compound (PR107:Reyan72059:Reyan73397 = 1:1:3) had the best viscoelasticity and the least internal resistance of rubber molecules. In addition, the cross-link density, tensile strength, elongation at break, and tear strength of H-3 vulcanized rubber were the largest, improved by 23.08%, 5.32%, 12.45% and 3.70% compared with the same H-2 vulcanized rubber. In addition, the heat generation performance was reduced by 11.86%, and the wear resistance improved. Full article

As an indispensable component of power transmission systems, the performance of porcelain insulators directly impacts the reliability and operational stability of electrical networks. To enhance the anti-fouling flashover capability of transmission lines, porcelain insulators are commonly coated with RTV (Room Temperature Vulcanizing) silicone rubber coatings. However, the unique environmental conditions prevalent in high-altitude regions, such as those in Qinghai, impose distinctive stresses on the performance and longevity of RTV coatings. This study provides an in-depth analysis of the operational and aging characteristics of RTV-coated porcelain insulators under such extreme conditions, with a focus on evaluating performance degradation mechanisms. By conducting comprehensive field investigations of climatic and environmental parameters in Qinghai, this research elucidates the effects of high-altitude environments on RTV coatings and proposes a systematic methodology for detecting and analyzing aging-related phenomena. This study discerns the aging patterns of insulator surface coatings in high-altitude regions and examines the pollution accumulation mechanisms of insulators under adverse climatic conditions. These findings offer critical insights for optimizing the selection, maintenance, and replacement strategies of insulators in high-altitude transmission networks, thereby enhancing the safety, reliability, and operational efficiency of power systems in such challenging environments. Full article

To address the challenges of unclear thermo-mechanical coupling mechanisms and unpredictable multi-field synergistic effects in segmented tire molds during vulcanization, this study focuses on segmented tire molds and proposes a multi-physics coupling numerical model. This model integrates fluid flow dynamics into heat transfer mechanisms. It systematically reveals molds’ heat transfer characteristics, stress distribution and deformation behavior under combined high-temperature and mechanical loading. Based on a fluid-solid-thermal coupling framework and experimental validations, simulations indicate that the internal temperature field of the mold is highly uniform. The global temperature difference is less than 0.13%. The temperature load has a significant dominant effect on the deformation of key components such as the guide ring and installation ring. Molding forces play a secondary role in total stress. The error between multi-field coupling simulation results and experimental results is controlled within 6%, verifying the model’s reliability. This research not only provides a universally applicable multi-field coupling analysis method for complex mold design but also highlights the critical role of temperature fields in stress distribution and deformation analysis. This lays a theoretical foundation for the intelligent design and process optimization of high-temperature, high-pressure forming equipment. Full article

Calcium lignosulfonate was incorporated into rubber compounds based on styrene–butadiene rubber (SBR) and acrylonitrile–butadiene rubber (NBR) in amounts ranging from 10 to 60 phr. A sulfur-based curing system and a peroxide curing system consisting of dicumyl peroxide in combination with methacrylic acid zinc salt were used for cross-linking of the compounds. The aim of the work was to investigate the influence of lignosulfonate and curing system composition of the cross-linking process, morphology, physical–mechanical and dynamic–mechanical characteristics of the composites. The achieved results showed that peroxide cured composites demonstrated higher cross-link density, which was found not to be influenced by the content of lignosulfonate. The cross-link density of sulfur-cured composites was lower and showed a decreasing tendency with increasing amounts of the biopolymer. A lower cross-linking degree was reflected in a higher elongation at break and higher increase in the elongation at break of the corresponding composites. On the other hand, peroxide-cured composites exhibited a higher modulus M100 and higher hardness. The microscopic analysis revealed that co-agent in peroxide vulcanization contributed to the improvement of adhesion between the biopolymer and the rubber resulting in higher tensile strength of the equivalent composites. The higher cross-link density of peroxide-cured composites caused higher restriction of the chain segments’ mobility, due to which these composites exhibited a higher glass transition temperature. Full article

The damping performance of chlorinated butyl rubber (CIIR) is exceptional; however, its poor processability during vulcanization can lead to numerous defects. Natural rubber (NR) and ethylene propylene diene monomer rubber (EPDM) were selected to blend with CIIR for improving its processing performance. Their effects on the vulcanization characteristics, mechanical properties, and damping performance were investigated. Blending CIIR with NR can considerably increase the vulcanization speed of the rubber compound and improve production efficiency. The tensile strength of the vulcanizate first increases with an increase in the dosage of NR in NR/CIIR, and subsequently, it decreases before increasing again. The tensile strength first increases and then decreases with an increase in the EPDM dosage in EPDM/CIIR vulcanizate. The tensile strength increases by 15.6%when the EPDM dosage is 60 and 80 phr. EPDM and NR have similar effects on the damping performance of CIIR, which were evaluated by fitting the data of loss factor (∆tanδ) versus NR or EPDM dosage. Therefore, the quantity of NR or EPDM can be conveniently calculated based on performance requirements when designing the formula of the CIIR matrix materials. Full article

Direct ink writing (DIW) is an economical, straightforward, and relatively energy-efficient 3D printing technique that has been used in various domains. However, the utilization of rubber latex for DIW remains limited due to its high fluidity and inadequate support, which makes it challenging to meet the required ink rheological characteristics for DIW. In this study, a concentrated pre-vulcanized natural rubber latex (CPNRL) ink with a high solid content of 73% without additives is developed for DIW 3D printing. The CPNRL ink is concentrated using superabsorbent polymer (SAP) beads, which demonstrates good colloidal stability, favorable rheological properties, and superior printability. The impact of printing angles on the mechanical properties of the rubber specimens based on the CPNRL-73 ink is explored in detail, wherein the tensile strength of the specimen printed at a 90° angle reaches an impressive 26 MPa and a strain of approximately 800%, which surpasses the majority of 3D-printed rubber latex specimens. Additionally, the CPNRL ink can be used to print a wide range of intricate shapes, demonstrating its advantages in excellent formability. The preparation of 3D printable ink using the absorption method will expand the application of elastomers in fields such as customized flexible sensing and personalized rubber products. Full article

Zinc oxide (ZnO) particles were successfully synthesized through the green method using aloe vera extract and zinc nitrate (1:1). The structure, morphology and properties of the biosynthesized ZnO (bioZnO) particles were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), time of flight secondary ion mass spectrometry (TOF-SIMS) and thermogravimetry (TG). The morphology and the size of ZnO particles were elucidated by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). Then, the ability of bioZnO to activate sulfur curing of natural rubber (NR) was tested and compared to commercial ZnO traditionally used as vulcanization activator. The bioZnO showed similar activity in the vulcanization process to commercial ZnO. NR composites containing bioZnO were pro-ecological in nature and exhibited better mechanical characteristics and durability against thermo-oxidative aging than NR with commonly used micrometric ZnO. Moreover, NR vulcanizates containing bioZnO showed good mechanical properties in dynamic conditions and satisfactory thermal stability. The present research is new and in addition to the analysis of biosynthesized ZnO particles, the effect of the activator in the vulcanization process of the NR elastomer and its influence on the properties of the final products were additionally discussed. Full article

The substantial waste generated during the processing of hides and skins as well as at other stages of manufacturing is a recurring issue in the leather industry that this article attempts to address. To investigate the mechanical and thermal characteristics of the resultant composites, this study suggests using leather waste from the bovine leather industry, analyzes the tanning process, and assesses the viability of mixing this waste with natural rubber (TSR-20). Without the inclusion of leather waste, the resulting composites had exceptional tensile strength, surpassing 100% of rubber’s strength. The effective interaction of the recycled leather particles with the natural rubber matrix was evidenced using the Lorentz–Park equation. This better performance points to a competitive relationship between rubber and leather waste. The samples’ density was 10% greater than that of polybutadiene elastomers and 10% greater than that of natural leather, while the hardness was comparable to that of PVC, which is frequently utilized in the design of general-purpose soles. This suggests that waste from the leather industry can be efficiently utilized in sustainable applications, particularly in the production of leather goods and shoes, helping to valorize waste that is typically discarded. Furthermore, by encouraging the use of recycled resources in the creation of new compounds, this plan provides the rubber sector with a sustainable option. To optimize this proposal, perhaps will be necessary to identify different vulcanization systems to improve the physical mechanical properties and other uses derived from the optimizations realized. This composite can be applied in the fashion industry in order to develop new trends around the application of waste and residues for a natural design line. Through the research process, it was possible to integrate the residues into the natural rubber matrix, as evidenced in the characterization process. Full article

The use of hydrogen as fuel presents many safety challenges due to its flammability and explosive nature, combined with its lack of color, taste, and odor. The purpose of this paper is to present an electrochemical sensor that can achieve rapid and accurate detection of hydrogen leakage. This paper presents both the component elements of the sensor, like sensing material, sensing element, and signal conditioning, as well as the electronic protection and signaling module of the critical concentrations of H₂. The sensing material consists of a catalyst type Vulcan XC72 40% Pt, from FuelCellStore, (Bryan, TX, USA). The sensing element is based on a membrane electrode assembly (MEA) system that includes a cathode electrode, an ion-conducting membrane type Nafion 117, from FuelCellStore, (Bryan, TX, USA). and an anode electrode mounted in a coin cell type CR2016, from Xiamen Tob New Energy Technology Co., Ltd, (Xiamen City, Fujian Province, China). The electronic block for electrical signal conditioning, which is delivered by the sensing element, uses an INA111, from Burr-Brown by Texas Instruments Corporation, (Dallas, TX, USA). instrumentation operational amplifier. The main characteristics of the electrochemical sensor for hydrogen leakage detection are operation at room temperature so it does not require a heater, maximum amperometric response time of 1 s, fast recovery time of maximum 1 s, and extended range of hydrogen concentrations detection in a range of up to 20%. Full article

Given the growing interest of the rubber industry in seeking alternatives that contribute to environmental sustainability, this work aims to present a study of the mechanical, thermal, and structural properties of natural rubber composites using tannin extracted from Acacia mearnsii as an antioxidant agent. Tannin is a natural and biodegradable product, rich in polyphenols and known for its antioxidant properties. The analyses assessed the effectiveness of incorporating tannins (0, 1, 1.5, and 2 parts per hundred rubber) into sulfur-crosslinked natural rubber composites using a binary accelerator system across three distinct vulcanization schemes: conventional, semi-efficient, and efficient. Initially, tannin characterization tests were conducted, revealing characteristic polyphenol bands of proanthocyanidin catechins, a high total phenolic content, and a substantial reduction in antioxidant activity. These findings highlight the significant antioxidant potential of tannins, particularly for industrial and biological applications. The analyses of the characteristics of natural rubber composites with tannin incorporation indicated that the type of vulcanization process directly affects the antioxidant action of the plant tannin, with the tannins being most effective in the efficient system due to the formation of monosulfidic and disulfidic bonds. Furthermore, the incorporation of tannin did not compromise the physical and chemical properties of the materials, highlighting it as a viable additive for the rubber industry. Full article

This work investigates the relationship between the mean diameter of palladium (Pd) nanoparticles and their surface energy, specifically in the context of alkaline ethanol electro-oxidation for fuel cell applications. Employing a recent generalization of the classical Laviron equation, we derive crucial parameters such as surface energy (σ), adsorption–desorption equilibrium constant (K_eq), and electron transfer coefficient (α) from linear voltammograms obtained from Pd-based nanoparticles supported on Vulcan carbon. Synthesized using two distinct methods, these nanocatalysts exhibit mean diameters ranging from 10 to 41 nm. Our results indicate that the surface energy of the Pd/C nanocatalysts spans σ ~ 0.5–2.5 J/m², showing a linear correlation with particle size while remaining independent of ethanol bulk concentration. The adsorption–desorption equilibrium constant varies with nanoparticle size (~0.1–6 × 10⁻⁶ mol⁻¹) but is unaffected by ethanol concentration. Significantly, we identify an optimal mean diameter of approximately 28 nm for enhanced electrocatalytic activity, revealing critical size-dependent effects on catalytic efficiency. This research contributes to the ongoing development of cost-effective and durable fuel cell components by optimizing nanoparticle characteristics, thus advancing the performance of Pd-based catalysts in practical applications. Our findings are essential for the continued evolution of nanomaterials in fuel cell technologies, particularly in improving efficiency and reducing reliance on critical raw materials. Full article

This study presents data on the use of shungite ore (the Bakyrchik deposit, Kazakhstan) and its concentrate as fillers in elastomer composites based on nitrile butadiene rubber. In addition to carbon, these shungite materials contain oxides of Si, Fe, K, Ca, Ti, Mn, and Al. The shungite concentrate was obtained through a flotation process involving five stages. The chemical composition analysis of these natural fillers revealed that during flotation, the carbon content increased 3.5 times (from 11.0 wt% to 39.0 wt%), while the silicon oxide content decreased threefold (from 49.4 wt% to 13.6 wt%). The contents of oxides of K, Ca, Ti, Mn, and Al decreased by less than 1%, and iron oxide content increased by 40% (from 6.7 wt% to 9.4 wt%). The study explored the impact of partial or full replacement of carbon black (CB) of P 324 grade with the shungite ore (ShO) and the shungite concentrate (ShC) on the vulcanization process and the physical–mechanical properties of the rubber. It was found that replacing CB with ShO and ShC reduces Mooney viscosity ML (1 + 4) 100 °C of the rubber compounds by up to 29% compared to the standard CB-filled sample. The use of the shungite fillers also increased scorch time (t_s) by up to 36% and cure time (t₉₀) by up to 35%. The carbon content in the shungite fillers had little influence on these parameters. Furthermore, it was demonstrated that replacing 5–10 wt% of CB with ShO or ShC improves the tensile strength of the rubber. The results of the flotation enrichment process enable the assessment of how these shungite fillers affect the properties of the composites for producing rubbers with specific characteristics. It was also found that substituting CB with ShO or ShC does not significantly affect the rubber’s resistance to standard oil-based media. The findings indicate that Kazakhstan’s shungite materials can be used as fillers in rubber to partially replace CB. Full article

In-rubber properties of vulcanizates deteriorate in the presence of incorporated recycled ground rubber (GR). This behavior is partly explained by a possible diffusion of sulfur from the rubber matrix into the GR. Therefore, the sulfur concentration and, thus, the crosslink density in the matrix are reduced. This phenomenon was further investigated in this research work using two spatially resolved methods that supplement each other: the diffusion of soluble sulfur in GR-containing compounds was locally investigated via Micro X-Ray Fluorescence analysis. Viscoelastic properties were also determined spatially by the Micro Dynamic-Mechanical Indentation method. Combining the results of both methods, local concentrations of sulfur were related to local viscoelastic properties, revealing great differences in crosslink density at the interface between the GR and matrix material. In this way, it is shown that sulfur is capable of diffusing several mm, which locally doubles its concentration with respect to the sulfur content of the compound formulation. This, in turn, negatively impacts the homogeneity of crosslink density in both the matrix and GR, revealing a local increase in the elastic stiffness of 100 %. In addition, it was found that the vulcanization characteristics of the used polymers determine the amount of sulfur diffusion and, thus, the change in viscoelastic properties. Full article

It is highly desired yet challenging to develop advanced elastomers with excellent mechanical properties, including high strength and toughness. In this work, strong and tough rubber/rubber compound vulcanizates were facilely prepared by blending ethylene-propylene-methylene (EPM) and isoprene rubber (IR) together with dicumyl peroxide (DCP) and subsequent vulcanization, since both EPM and IR can be vulcanized synchronously by DCP and the well-crosslinked structure of EPM/IR vulcanizate presented a stable phase separation state. By tuning their composition, EPM/IR vulcanizates could present remarkably improved mechanical strength and toughness, as well as excellent energy dissipation and deformation recovery abilities. Furthermore, EPM/IR/SiO₂ nanocomposites with better properties were prepared by introducing silica nanoparticles into EPM/IR vulcanizates. It was found that the high toughness and strength of EPM/IR vulcanizates and EPM/IR/SiO₂ nanocomposites mainly resulted from the combination of stretchability of EPM and strain hardening of IR. Their excellent energy dissipation and deformation recovery abilities were related to the macromolecular characteristics of EPM and IR, compatibility between EPM and IR, and their crosslinking dynamics. Full article