Mechanism Governing the Enhanced Tribological Properties of Graphene-Modified Nitrile Butadiene Rubber

This paper compares the differences developed in rubber properties between compression and transfer molding methods for various types of polymers. It has been shown that the two molding methods produce distinctly different rubber properties for the same elastomer. Acrylonitrile butadiene rubber (NBR) shows little difference in durability between molding methods. Transfer molding (TM) reduces modulus and hardness of NBR, but improves compression set. The crosslink density of rubbers made with TM is higher than those made with compression molding (CM). Highly saturated acrylonitrile butadiene rubber (HNBR) properties are significantly different between the two molding methods. As for NBR rubbers, the TM method reduces modulus and hardness, but improves compression set. The crosslink density of rubbers made by TM is higher that those made with CM. Silicone rubber (VMQ) that does not require post cure shows the same rubber properties change as NBR. Transfer molding yields low tensile and modulus but better compression set. Polyacrylic rubber (ACM) molded with the TM method shows reduced tensile, elongation, modulus and hardness; but after post cure, modulus and hardness did not show substantial differences. The compression set was lower with TM both before and after post cure. Crosslink density is significantly higher with TM, but the difference diminishes after post cure. Ethylene acrylic rubber (EAM) and fluoroelastomer rubber (FKM) exhibit property changes similar to acrylic rubber when molded either with compression or transfer molding methods. Rubbers molded with TM methods showed a higher degree of anisotropy in rubber properties than with CM. With enlarged extension ratio, the coefficient of anisotropy increased, with the exception of ACM.

The use of plasticizers based on esters of various acids most effectively improves the processing of rubber compounds and the frost resistance of NBR-based rubbers. In this work, as a plasticizer, products based on vegetable raw materials were tested - Phytonorman oils produced by the Biochemical Holding ORGKHIM, which are di- and triglycerides containing fatty acids of tall oil. Model rubber compounds based on BNKS-18AMN contained 10, 20, 30 wt. including eco-oils of the Phytonorman 212 and Phytonorman 213 brands, a mixture without oil and with 10 wt. including dibutyl phthalate (DBPh). To assess the effect of the type and dosage of eco-oils on the properties of rubbers and rubber compounds, methods for studying technological, physical-mechanical and adhesive properties were used. Determination of frost resistance, a comparison was made of methods for determining the glass transition temperature: differential scanning calorimetry (DSC) and thermomechanical analysis (TMA, Fourier). When using vegetable oils Phytonorman -212 and Phytonorman -213, the technological properties of rubber compounds are significantly improved compared to the mixture without oil and are on the same level with DBPH traditionally used in nitrile rubbers. It has been established that the introduction of Phytonorman 213 eco-oil into the formulations of rubber compounds based on BNKS 18AMN up to 10 wt. hours allows you to improve the technological parameters, as well as lower the glass transition temperature of rubber. At the same time, the physical and mechanical parameters and adhesive properties of vulcanizates are reduced by an average of 10%. It is also worth noting that rubbers with Phytonorman 213 oil are not inferior to nitrile rubbers with DBPh in terms of basic characteristics, and they are superior in adhesive properties by 27%.

Rubber composite is a high molecular weight polymer, produced from natural or synthetic rubber with sulfur as its common crosslinking agent. To improve the mechanical properties of rubber, filler with high silica content was usually added. Hence in this experiment, due to their high silica content, Risk husk ash (RHA), along with chemizil and zeosil were used as the composite filler. Sulfur was chosen as the crosslinking agent of a rubber mixture that consists of polyisoprene rubber (IR), acrylonitrile butadiene rubber (KNB), and polybutadiene rubber (BR). The composition of the other component was fixed at Per Hundred Rubber (PHR) of 51.43. During mixing, the temperature and mixing time were kept constant at 60-70oC and 6 minutes. The properties of rubber composite were characterized based on their physical and mechanical properties. Based on the rheological test, RHA has a faster vulcanization time compared to chemisil and zeosil. Improvement of the mechanical properties of the RHA rubber mixture was also observed, with 300% modulus, elongation, and tear at 42 kg/cm2, 867%, and 51 kg/cm2. Meanwhile, insignificance differences in tensile strength, hardness, and specific gravity of RHA compared to chemisil and zeosil, were observed.

This work focused on using silica fume (by product) and quartz (industrial waste) in manufacture of ferrosilicon alloys in Egyptian chemical industries company (KIMA), in Aswan, Egypt. To reinforce the properties of Nitrile rubber, reduce cost and save the environment from industrial waste. Preparation rubber composites by addition different concentrations from silica fume filler (byproduct) and quartz filler (industrial waste). Investigation on the insulation properties of nitrile rubber composites by measurement of flashover voltage for unfilled nitrile rubber (blank) and nitrile rubber composites with silica fume filler and quartz filler. The measurement of flashover voltage for nitrile rubber composites occurred in different conditions (dry, wet, salinity and acidity). The effect of silica fume filler and quartz filler on mechanical properties of nitrile rubber was studied by investigation on elongation at break for nitrile rubber composites and also tensile strength. Studied the effect of hybrid filler on enhancement of electrical properties and mechanical properties of nitrile rubber, by addition different concentrations of mica filler on the samples showed the least enhancement in insulation properties of nitrile rubber composites in case of silica fume and quartz filler. And also study the morphology of nitrile rubber composites. http://ejchem.journals.ekb.eg/article_3828.html

The study aims to evaluate the frequency and temperature-dependent viscoelastic properties of natural rubber (NR) and nitrile butadiene rubber (NBR) for vibration damping applications. The dynamic mechanical analysis (DMA) tests were conducted on NR and NBR at low frequencies, from room temperature to 112 °C. The experimental data were fitted using the generalized Maxwell model, and vibration tests were conducted to obtain dynamic properties such as natural frequencies, damping ratio, and quality factor. The loss factor for NR increased significantly above 80 °C, while for NBR, it decreased above 50 °C. At higher temperatures, both NR and NBR exhibited faster relaxation, but NR had a higher loss factor, indicating a better damping ability. The relaxation strength of NR increased above 60 °C, whereas that of NBR decreased, highlighting the differences in their damping abilities. NBR showed greater damping ability at the first natural frequency, while NR performed better at the second and third natural frequencies. According to the experimental findings, NR proves to be better suited for damping in high-temperature conditions, while NBR is more suitable for low-temperature damping applications. The relaxation modulus of NR is lower than that of NBR at lower temperatures, leading to a better damping performance for NR at higher temperatures. The study recommends using NR for high-temperature applications where high damping is required and NBR for low-temperature applications that require moderate damping.

Acrylonitrile-butadiene rubber elastomers are widely used in seal and tire industries. Physiochemical, surface and tribological properties of acrylonitrile-butadiene rubber exposed to a lubricant in a sealed mechanical contact may gradually change, in particular, at elevated temperatures. In this study, industrial-grade acrylonitrile-butadiene rubber elastomers were aged in two model non-additivated base oils, namely non-polar hexadecane and polar diethylene glycol dibutyl ether at both ambient (298 K) and elevated (398 K) temperatures from 1 to 168 h. Mass changes of acrylonitrile-butadiene rubber before and after ageing indicated that acrylonitrile-butadiene rubber had distinct ageing dynamics in different model base oils and at different temperatures. For acrylonitrile-butadiene rubber aged in nonpolar hexadecane, the rate of weight loss of the rubber was larger at 398 K compared to that at 298 K. On the contrary, distinct weight-gaining (swelling) dynamics were observed for acrylonitrile-butadiene rubber aged in polar diethylene glycol dibutyl ether at 298 and 398 K. Based on Fourier transform infrared spectroscopy, liquid and solid-state nuclear magnetic resonance spectroscopy and energy dispersive spectroscopy analyses, it was found that aldehydes and sulfur- and zinc-containing compounds were leached out from acrylonitrile-butadiene rubber aged in both hexadecane and diethylene glycol dibutyl ether. The results of tribological studies showed that the non-aged acrylonitrile-butadiene rubber has a good wear-resistance. Acrylonitrile-butadiene rubber samples had a very similar surface topography before and after tribo-tests. However, the worn surfaces of acrylonitrile-butadiene rubber samples were characterized by fine scoring (abrasion) marks after ageing in both model base oils. This has been attributed to changes in the steel–rubber contact environment during the sliding process and degradation of mechanical properties of acrylonitrile-butadiene rubber after ageing. For one acrylonitrile-butadiene rubber sample (after ageing in hexadecane at 398 K), very stable friction in the steel–rubber contact was observed.

Effect of the type of activator in salt vulcanisation on the structure and properties of butadienenitrile rubber containing ester groups

Molecular dynamics simulation of mechanical and tribological properties of nitrile butadiene rubber with different length and content carbon nanotubes

Nitrile rubber is a widely used rubber, so its basic mechanical properties are very important. In order to improve the mechanical properties of nitrile butadiene rubber (NBR), Mg‐Al hydrotalcite was introduced into NBR by mechanical blending and hot pressing, and the mechanical properties of the composites were studied. The results show that, compared with NBR, the maximum MH‐ML of 2%LDH/NBR composites reaches 1.795 N·m, and an is improved by 8.7%. The T90 of NBR and 2%LDH/NBR composites insignificant changed. In terms of mechanical performance, the optimal performance is achieved when two parts of layered double hydroxide (LDH) are added. Compared with the original NBR, the tensile elongation at break, tear strength, and 100% modulus stress increased by 11.6%, 7.1%, and 29.1%, respectively. The addition of LDH also has a certain influence on the thermal conductivity of the composites. Compared with the original NBR, the peak thermal conductivity of NBR with two parts of LDH increased by 2.4 mW. Under the condition of low filling, the mechanical properties such as elongation at break and tear strength of LDH/NBR composites have been improved, which provides a reference for the development of mechanical properties research of NBR.

Electrophysical, rheometric and physicomechanical properties of rubber based on butadiene-nitrile rubber filled with technical carbon were studied for its application as sensitive elements of flexible variable capacities in sensors of remote pressure monitoring systems in automobile tires. Polytetrafluoroethylene, graphene and titanium dioxide were studied as modifiers of the electrophysical properties of rubber. The rubber mixture was prepared on laboratory rollers LB 320 160/160 at a roller surface temperature of 60-70 °C for 25 min. Rheometric properties of the rubber mixture were studied on a rheometer MDR 3000 Basic at 150 °C for 30 min in accordance with ASTM D2084-79. To determine the physical and mechanical properties, the rubber mixture was vulcanized at a temperature of 150 °C and a pressure of 18.2 MPa for 20 min in a P-V-100-3RT-2-PCD vulcanization press. The elastic strength properties of vulcanizates were determined in accordance with GOST 270-75; Shore A hardness – in accordance with GOST 263-75; tear resistance – in accordance with GOST 262-93; rebound elasticity – in accordance with GOST 27110-86. For rubber samples with a thickness of 0.3 to 1.5 mm with copper electrodes glued to both sides, the electrical capacity was measured and studied as a function of pressure on a TS-7 device. The specific surface resistance of the rubber samples was determined by the standard four-probe method on a Jandel RMS 3000 installation. It was found that rubber containing 10 parts by weight of titanium dioxide per 100 parts by weight of titanium dioxide. part butadiene-nitrile rubber, is characterized by increased electrical capacity and can be recommended as an interlining material for a variable capacitor of a pressure sensor in automobile tires. For citation: Smirnov A.V., Terentyev A.A., Balasanyan S.A., Egorov E.N., Kol’tsov N.I., Vasiliev S.A. Study of electrophysical properties of rubber based on nitrile-butadiene rubber and carbon technical as an interlining material of flexible variable capacities. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 9. P. 99-105. DOI: 10.6060/ivkkt.20256809.9y.

This paper investigated the mechanism of enhancing the mechanical and tribological properties of nitrile rubber (NBR) via the addition of nano-SiO2 on the molecular scale. Molecular dynamics (MD) simulations were performed on molecular structure models of pure NBR, NBR/SiO2, and three-layer friction pairs. The results showed that the hydrogen bonds and interfacial interaction between nano-SiO2 and NBR molecular chains decreased the fractional free volume of NBR nanocomposites and increased the shear modulus of NBR by 25% compared with that of pure NBR. During the friction process, nano-SiO2 decreased the radius of gyration of NBR molecular chains and effectively lowered the peak atomic velocity, the peak temperature, and the peak friction stress at the interface between NBR and copper atoms. The average friction stress on NBR/SiO2 was 34% lower than that on NBR, which meant the tribological properties of NBR were significantly improved by nano-SiO2. The mechanism of nano-SiO2-reinforcing NBR on a molecular scale can lay a theoretical foundation for the design of water-lubricated rubber bearings.

The effects of oxidative aging on the static and dynamic properties of nitrile rubber at the molecular scale were investigated by molecular dynamics simulation. The aged nitrile rubber models were constructed by introducing hydroxyl groups and carbonyl groups into rubber molecular chains to mimic oxidative aging. The static and dynamic properties of the unaged and aged nitrile rubber under different conditions were evaluated by mean square displacement, self-diffusion coefficients, hydrogen bond, fractional free volume, radial distribution function, cohesive energy density and solubility parameter. The results show that the elevated temperature intensified significantly the mobility of rubber molecular chains and fractional free volume, while the compressive strain displayed the opposite effect resulting in packing and rearrangement of rubber chains. The introduction of hydroxyl groups and carbonyl groups enhanced the polarity, intermolecular interactions, the volume and rigidity of molecular chains, implying weaker mobility of molecular chains as compared to unaged models. The compressive strain and oxidative aging both decreased the fractional free volume, which inhibited gaseous and liquid diffusion into the rubber materials, and slowed down the oxidative aging rate. This study provides insights to better understand the effect of molecular changes due to oxidative aging on the structural and dynamic properties of rubber materials at the molecular level.

In this study, different types of antioxidants as well as graphene were incorporated into nitrile rubber to enhance the thermo-oxidative aging and tribological properties of nitrile rubber. Molecular dynamics simulations were employed to determine critical parameters of the composite system, including the solubility parameter (δ) and mean square displacement (MSD). Based on these calculations, the effects of antioxidant RD (1,2-dihydro-2,2,4-trimethylquinoline) and antioxidant 4010NA (N-isopropyl-N’-phenyl-p-phenylenediamine) on the thermo-oxidative aging performance and tribological properties of Graphene (GNS)/Nitrile Rubber (NBR) composites were systematically analyzed. The results indicate that the GNS/RD/NBR composite exhibits good compatibility and low mean square displacement. Furthermore, experimental results demonstrate that the composite possesses excellent tribological and mechanical properties. This study elucidates, from an atomic perspective, the microscopic mechanism by which the synergistic effects of various antioxidants and graphene influence the thermo-oxidative aging resistance and tribological properties of nitrile rubber, thereby providing theoretical guidance for the development of high-performance rubber materials.

To improve the tribological properties of nitrile butadiene rubber (NBR), nano-Fe3O4 particles with good lubricity were added into the NBR to prepare NBR/nano-Fe3O4 composites. In our experiment, surface microstructure of the composites was observed by JSM-5600LV low-vacuum scanning electron microscope; disposition of nano-Fe3O4 was measured by an energy dispersive x-ray spectrometer; friction and wear condition of the composites were tested by UMT-2MT friction testing machine, and friction condition of the composites were tested for different temperatures by SRV high temperature friction testing machine. The results showed that after adding nano-Fe3O4 particles in NBR, surface of the composites was smoother than NBR due to less defects and the tribological properties were significantly improved. Friction and wear rate of the composites were 300% lower than NBR, and we owe this to the nano-Fe3O4 particles that played a role as solid lubricant on the surface of the composites. Meanwhile, friction coefficient was greatly affected by friction time; when the friction time was more than 10 min, the friction coefficient would become larger and there would be more abrasion; the friction coefficient of the composites was less affected by the temperature with the additional increase in nano-Fe3O4 particles.

This paper, investigated the effects of expandable graphite and ammonium polyphosphate on the flame-retardant properties of nitrile butadiene rubber. Several formulations of NBR were prepared by combining different ratios of expandable graphite and ammonium polyphosphate to evaluate their synergistic flame-retardant effects. The results show that the combination of expandable graphite and ammonium polyphosphate significantly enhances the flame-retardant effects of nitrile butadiene rubber, as evidenced by improved limiting oxygen index values, horizontal burning rates decreased and passed the UL-94 V1 when the ratio of expandable graphite and ammonium polyphosphate as (2/1). Results from TGA demonstrated that the ammonium polyphosphate/expandable graphite combination could retard the degradation of rubber by promoting the formation of a compact char layer on the condensed phase surface. This char layer effectively protects the matrix from heat penetration and the diffusion of flammable gas products, resulting in better flame-retardant performance. The effect of flame retardant on the mechanical properties of nitrile butadiene rubber was also evaluated. The results showed that the mechanical properties decreased with increasing flame retardant content.