Nitrile Rubber Research Articles

Multiphase modeling of pressure-dependent hydrogen diffusivity in fractal porous structures of acrylonitrile butadiene rubber-carbon black composites with different fillers

The hydrogen diffusivities of acrylonitrile butadiene rubber (NBR) composites with different types and contents of carbon black (CB) fillers were investigated in the exposure pressure range of 0.5–10 MPa using a volumetric analysis system. These measured diffusivities exhibited distinct pressure-dependent behavior. The diffusivities of unfilled NBR and NBR composites containing medium-thermal CB filler decreased from 39.7 × 10−11 m2/s to 9.4 × 10−11 m2/s as the pressure increased. On the other hand, the pressure-dependent diffusivities of NBR composites containing high-abrasion furnace, fast-extrusion furnace and semireinforcing furnace CB fillers revealed left-biased unimodal shaped curves, with peak values ranging from 19.7 × 10−11 m2/s to 5.6 × 10−11 m2/s. To model this observed behavior, the diffusion resistance theory with a heterogeneous NBR–CB composite and a fractal porous structure for H2 was introduced. The theoretical parallel diffusion resistance model was found to coexist independently as the surface, Knudsen, and bulk diffusion phases. This theoretical multiphase modeling was applied to the measured diffusivities, determining diffusion resistance parameters for each phase. The obtained individual parametric characteristics for each diffusion were interpreted by considering the CB filler content and volume fraction of the filler. As a result, the diffusivities calculated by multiphase diffusion modeling were in quite agreement with the measured diffusivities for all investigated specimens, where the determined squared correlation coefficient (R2) by fitting process was in the range from 0.69 to 0.97.

Revealing the unique characteristics and strength of polycarbodiimide as an accelerator‐free crosslinker for low‐temperature processing of carboxylated nitrile butadiene rubber gloves for hand protection

Revealing the unique characteristics and strength of polycarbodiimide as an accelerator‐free crosslinker for low‐temperature processing of carboxylated nitrile butadiene rubber gloves for hand protection

Hydrogen permeation behavior and mechanisms in nitrile butadiene rubber composites for hydrogen sealing

As the most widely used sealing component in hydrogen systems, rubber seals are affected by hydrogen over long-term service. Hydrogen molecules can dissolve into rubber materials and diffuse through the material. Studies have shown that adding fillers can enhance rubber's performance, improve its compatibility with hydrogen, and reduce the damage caused by hydrogen diffusion. Therefore, this study integrates experimental hydrogen permeation research with finite element modeling for nitrile butadiene rubber (NBR). The aim is to investigate the influence of filler properties on the microstructure, hydrogen permeation behavior, and hydrogen concentration distribution within NBR. Ultimately, the study elucidates the mechanisms governing hydrogen distribution evolution and permeation in NBR under hydrogen environments. The results indicate that the crosslink density of NBR filled with carbon black (NBR-CB) and silica (NBR-SC) is directly proportional to the filler content. NBR with higher filler content exhibits a lower hydrogen permeation coefficient and superior hydrogen barrier properties. In contrast to silica fillers, carbon black fillers demonstrate strong adsorption and a more pronounced barrier effect against hydrogen molecules, thereby enhancing the hydrogen barrier efficiency. The increase in carbon black's hydrogen solubility (from 2.2 × 10-4 to 16.9 × 10-4 cc(STP)·cm-3(polymer)·cmHg-1) effectively reduces the hydrogen permeation coefficient. In contrast, the rise in carbon black's hydrogen diffusion coefficient (from 0.1 × 10-6 to 4.1 × 10-6 cm2·s-1) exacerbates the overall hydrogen permeation coefficient of NBR-CB, thereby intensifying the hydrogen permeation process.

Unveiling the Pressure-Induced Dynamics on the Glass Transition Temperature of Hydrogenated Nitrile Rubber

Unveiling the Pressure-Induced Dynamics on the Glass Transition Temperature of Hydrogenated Nitrile Rubber

Influence of Epoxy Resin Interlayer Interfaces on Electrical Tree Growth and Breakdown Characteristics.

The solid-solid insulation interface structure is a typical interface in extra-high-voltage power equipment, in which the multilayer epoxy resin material is a key component in the insulation structure of the power equipment, and the study of its interface characteristics is the most important. In this paper, epoxy-epoxy cross-linking interface specimens were prepared through experiments, and the degree of cross-linking between the interfaces was analyzed by changing the ratio of the curing agent and adding hydroxyl-terminated liquid nitrile rubber (HTBN) particles; it can be concluded that there exists a weak cross-linking reaction between the interfaces. The electrical tree measurement and alternating current (AC) breakdown test platform were set up, and three different cases of no interface, the electric field direction parallel to the interface, and the electric field direction perpendicular to the interface were tested, through which it was concluded that the existence of the interface inhibited the development of the electrical tree. For the three different cases of AC breakdown tested, it was concluded that the presence of an interface enhances the AC breakdown strength when the electric field direction is parallel to the interface and decreases the AC breakdown strength when the electric field direction is perpendicular to the interface through the interface, affecting the charge transport.

(Invited) Microwires Based on Carbon Nanotubes for Medicine and Biology

Flexible and biocompatible microwires are generally employed for biomedical implants in medicine, more specifically in neuroscience. These microwires used as electrodes need to be chemically inert and electrically conducting in order to record and stimulate the electrical activity of neurons in the nervous system. The electrodes available today are made of metals and silicon that lack the required flexibility resulting in a mechanical mismatch between soft tissues and rigid metals which induces faster biofouling and inconsistent performance for long-term implants. Biofouling triggered by inflammatory responses dramatically affects the performance of neural electrodes, resulting in decreased signal sensitivity and consistency over time. Thus, long-term clinical applications require electrically conducting flexible electrode materials with reduced dimensions and antibiofouling properties. These characteristics reduce the degree of inflammatory reactions and increase the lifetime of implanted neural electrodes. Carbon nanotubes (CNTs) are well known for their flexibility, electrical conductivity, and chemical inertness. This talk will report the fabrication of CNT fibers and subsequent coating using a biocompatible flexible polymer hydrogenated nitrile butadiene rubber (HNBR). Unlike the gold standard parylene-C coating that requires processing under vacuum, dissolved elastomer HNBR polymer can deposit uniform coating in solutions. Polymer dip-coating has been employed for uniform and continuous coating of meters-long CNT fibers of multiple diameters (26 to 66 mm) to evaluate the robustness of the approach. The polymer was able to provide uniform thickness and pinhole-free coating along the CNT fiber. Furthermore, the polymer has been shown to be biocompatible when tested with in vitro elusions and culturing neurons. The covalent functionalization of CNT microwire cross-section interfacing with the neurons using hydrophilic, anti-biofouling phosphorylcholine molecules displays reduced impedance and increased hydrophilicity. These CNT microwire assemblies are promising for the development of low-impedance neural electrodes with higher hydrophilicity and protein-fouling resistance to inhibit inflammatory responses.

Assessing the health risks of dermal exposure to heavy metals dust among nail salon technicians.

Nail salon technicians are susceptible to potential exposure to a diverse array of hazardous chemicals in the form of dust or vapors. One of the main routes of exposure is dermal contact. The aim of present study was to health risk assessment of dermal exposure to dust containing heavy metals in nail salon technicians. Dust sampling was done on the work surface of 20 available nail salon technicians. The concentration of five metals including cadmium, lead, chromium, nickel, and manganese were determined using ICP-MS. Afterwards, the United States Environmental Protection Agency (USEPA) guideline was used to estimate the potential health risks, including carcinogenic and non-carcinogenic risks, associated with the analyzed metals. Results indicated the mean concentrations of Pb, Cd, Ni, Cr and Mn were 0.7953±0.4373, 0.0952±0.0264, 0.7666±0.8629, 0.4900±0.5994 and 1.134±0.4736, respectively. The hazard quotient (HQ) of all metals was within the permissible value, while hazard index (HI) was greater than 1. The probability of cancer risk (CR) resulting from dermal exposure to Ni, Cd and Cr exceeded the acceptable risk levels (10-6-10-4), but CR calculated for Pb was less than allowable value. Implementation of engineering controls such as downdraft vented nail tables and portable source capture systems is necessary. Besides, the use of personal protective equipment such as disposable nitrile gloves, N95 respirator masks, and ensuring proper training on safe work practices is recommended.

Synthesis of a novel bio-based curing agent and the curing behavior of the corresponding epoxy asphalt system

Traditional epoxy asphalt is made from petroleum resources. However, petroleum-based materials may cause environmental pollution and are not renewable. In this study, a bio-based curing agent MYM was synthesized from Maleic anhydride and Myrcene. The cured epoxy EP/MYM with the weight ratio of 1:1 were prepared. When preparing the modified asphalt, carboxyl-terminated liquid nitrile butadiene rubber (CTBN) was incorporated into the EP/MYM system to obtain the EP/MYM/CTBN modified asphalt system (referred to EMC epoxy asphalt). Firstly, the chemical structure of MYM was characterized using Fourier transform infrared spectroscopy (FTIR). Secondly, the mechanical properties and thermal stability of the cured EP/MYM were investigated by tensile test and thermogravimetric analysis (TG). Thirdly, the novel EMC epoxy asphalt was prepared and its composition was optimized. The curing behavior of the EMC epoxy asphalt was investigated by differential scanning calorimetry (DSC). And the time-temperature-transition diagrams (TTT diagrams) were plotted to determine the optimal curing process. Then the surface micro-morphology of EMC epoxy asphalt was investigated by atomic force microscopy (AFM). Finally, the high-temperature viscoelastic properties of EMC epoxy asphalt were investigated using dynamic shear rheology (DSR) tests. The results showed that EP/MYM has better mechanical strength and more excellent flexibility than those of EP/MTHPA and EP/MHHPA. The weight ratio of EP:MYM:CTBN was 10:8:1.5, and the optimal amount of diluent was 8 % of the total weight of the modifier. The semi-empirical kinetic modes of curing reaction were used to plot the TTT diagram of EMC epoxy asphalt, thus determining its curing technique as 120℃/2 h+160℃/3 h. The cured EMC epoxy asphalt showed uniform alternation of light and dark areas in the AFM images, indicating good compatibility and stability. The high-temperature deformation resistance of EMC epoxy asphalt was significantly improved compared to the base asphalt. The novel epoxy asphalt system prepared in this research provides a new route for the development of echo-friendly epoxy asphalt.

PEDOT:PSS/XNBR films for low-temperature stretchable electromagnetic interference shielding

Electromagnetic interference shielding materials being sufficiently stretchable at low temperatures have a wider range of applications. Herein, stretchable electromagnetic shielding films for low temperatures applications with segregated conductive networks were produced by a simple method of evaporating carboxylated nitrile butadiene rubber (XNBR) latex containing lithium bis(pentafluoroethylsulfonyl)imide (Li–PFSI) doped poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS). It is proved that the mechanical and electrical properties can be improved by changing the crystallization of PEDOT by doping. For the composite film with 4 wt% PEDOT:PSS and 1.4 mm thickness, electromagnetic interference shielding efficiency can maintain at about 60 dB at 100 % strain and 48 dB at 150 % strain, being the highest among stretchable EMI shields reported. At −10 °C and 100 % strain, shielding efficiency of the composite film with 8 wt% PEDOT:PSS is about 32 dB, indicating that the stretchable film is promising in applications in wearable devices, flexible devices, etc. for EMI shielding at low temperatures.

Recyclability and self-healing capability in reinforced ionic elastomers

This study presents a comparative analysis of different sustainable alternatives for producing reinforced ionic elastomers that are not just mechanically robust but also excellent in recyclability and self-healing, marking a significant advancement in sustainable materials science. Ionically crosslinked carboxylated nitrile rubber (XNBR) was combined with conventional (carbon black and silica) and sustainable (cellulose and ground tire rubber) fillers. The sustainable fillers not only enhanced the mechanical performance (reinforcing character) but also maintained high healing efficiencies (>80 %). Notably, the incorporation of just 10 phr of waste-based ground tire rubber (GTR) produced by water jet grinding (WJ-GTR) resulted in a material capable of complete repair and recycling (100 % efficiency) after temperature-driven protocols, with mechanical properties and a reinforcement index comparable to those of conventional fillers such as silica. This achievement represents a major breakthrough in the field of sustainable composites, as it offers a unique blend of robust mechanical properties and environmental sustainability.

Superelastic Polymer Aerogel with Superamphiphilicity.

Elastic aerogels have become a research hot spot in both academia and industry recently. The reported elastic aerogels are all made of hard materials by controlling their shapes. Herein we report an elastic aerogel made of a polymer elastomer with entropy elasticity. In the aerogel, cross-linked carboxyl nitrile rubber nanoparticles with hydrophilicity are dispersed in hydrophobic derivative of styrene-maleic anhydride alternating copolymer, forming a very special micro-nano surface structure with hydrophilic protrusions and hydrophobic depressions on the aerogel wall; therefore, the aerogel is not only superelastic but also superamphiphilic. A leak-free phase-change composite was prepared using the aerogel and paraffin, which can maintain at phase change temperature of paraffin for a longer time than the traditional one. The aerogel is also extremely suitable for desalination evaporators in solar-driven interfacial evaporation technology due to its superamphiphilicity, superelasticity, and ability to absorb sunlight. Exceptional evaporation rate of 2.78 kg·m-2·h-1 and evaporation efficiency of 170% could be reached even without using expensive light-absorbing materials. The evaporation rate exceeds that of most evaporators with expensive light-absorbing materials, and the evaporation efficiency exceeds the theoretical limit of conventional 2D solar evaporators. Both the phase-change composite and the evaporator can be easily recovered because the novel superelastic aerogel reported in this work is also recyclable.

Water Absorption Effect on Tensile Properties of Linear Low-Density Polyethylene (LLDPE) Blend with Recycle Acrylonitrile Butadiene Rubber Gloves (NBRr) in Saline Water

Nowadays, waste acrylonitrile butadiene rubber glove (NBRr) has been studied for use in building materials. The primary limitation of using rubber in construction was its low water absorption capacity. The goal of this research is to investigate the effect of Linear Low-Density Polyethylene (LLDPE) on water absorption and the temperature differential (20 and 30 oC) of NBRr blender composite in distilled water (DW) and saline water (SW). The rubber glove has been blended with heated two-rolled mills at 120 °C. The substance had been compressed using a hot press. Five samples had already been created. The sample was formed like a dumbbell. The five samples were immersed in DS and SW for 30 days at temperatures of 25°C and 35°C, respectively. The result shown the tensile strength, elongation at break Eb and Young’s modulus of LLDPE/NBRr blend decrease. The tensile properties of saline water lower compare to distilled water due to corrosion and degradation. Saline water contains dissolved salts, which can contribute to corrosion and degradation of the materials. The presence of salts can accelerate chemical reactions, leading to the degradation of the polymer matrix and the rubber phase. This degradation can weaken the material and reduce its tensile strength. Moreover, as the temperature increases, the thermal energy also increases, causing the polymer chains to gain more kinetic energy. This increased energy disrupts the intermolecular forces and reduces the overall molecular interactions within the material. Weaker intermolecular interactions lead to a decrease in tensile strength. As conclusion, hydrothermal effect tensile properties when temperature increase tensile properties decrease. distilled water has better diffusion than saltwater. LLDPE/NBRr blend was discovered that both distilled and salt-water absorption resulted in a decrease in tensile properties.

Dual influence of graphene oxide/clay and electron beam radiation on the structure, mechanical, thermal, and antimicrobial properties of nitrile butadiene rubber nanocomposite

Infective diseases are becoming more popular, and managing them has become a great worry for humanity. A rubber nanocomposite based on nitrile butadiene rubber with graphene oxide (NBR/GO) and GO/nanoclay (montmorillonite, MMT) (NBR/GO/MMT) was fabricated by a simple technique, roll milling. The synergistic influence of the existence of GO, clay, and electron beam (EB)-radiation on the NBR nanocomposites was characterized using scanning electron microscopy (SEM), and Fourier-transform infrared (FT–IR) techniques to study the mechanical, thermal, and antibacterial properties. The antibacterial activity of the prepared rubber nanocomposites was estimated via the disk diffusion process against Gram-positive bacteria, Bacillus subtilis, Staphylococcus lentus, and Gram-negative bacteria ; Pseudomonas aeruginosa and Proteus mirabilis. The results demonstrated that the physico-mechanical performance was significantly reinforced by incorporating nano GO (6 phr) and clay with GO (3 phr/6 phr. NBR films have no antibacterial potential. GO increases the antibacterial efficiency of the NBR films. NBR/3% GO/3% clay film is the most effective in reducing bacterial growth and B. subtilis was the most sensitive bacteria for rubber treatments. The inhibition zone diameters of the un-irradiated and irradiated NBR/3% GO/3% clay films for B. subtilis were 18.03 ± 0.59 and 25.63 ± 0.98 mm, respectively. It could be concluded that because of its outstanding flexibility and human-body compatibility penetration, rubber in corporation with antimicrobial agents can be utilized for manufacturing medical and environmental products.

An interesting phase transition in polyamide 6/nitrile rubber blend induced by temperature and pressure and its effect on tribological performance

AbstractThe preparation of high‐performance rubber‐plastic blending elastomers has always been a research hotspot in the field of petroleum equipment. The two‐phase separation structure of the blend determines the macroscopic properties of the materials. It is of great significance to deeply explore the influence of processing technology on the two‐phase separation structure. In this paper, polyamide 6 (PA6)/nitrile rubber blends were prepared via the melt–compounding method. To meet the requirements of oil production and oil transport equipment, we investigated systematically the mechanical properties of the specimens exposed to different environments. The oil resistance and high‐temperature resistance of the blends were enhanced considerably with the addition of PA6. The temperature and pressure fields induced a novel transition from particle into fibrous phase based on Ostwald's ripening. However, this brand new transformation showed no benefits to the improvement of the frictional performance. Meanwhile, the relationship between aggregate structure and mechanical performance was demonstrated from the aspects of crystallization behavior and phase morphology.

Hydroxyapatite-Filled Acrylonitrile-Butadiene Rubber Composites with Improved Cure Characteristics and Reduced Flammability.

The goal of this work was to develop acrylonitrile-butadiene (NBR) elastomer composites filled with hydroxyapatite (HAP) characterized by improved cure characteristics and resistance to burning. Silane, i.e., (3-aminopropyl)-triethoxysilane, ionic liquid, i.e., 1-decyl-3-methylimidazolium bromide and surfactant, i.e., cetyltrimethylammonium bromide, were used to improve the filler's dispersibility in the elastomer matrix and to reduce the time and temperature of vulcanization. The effects of HAP and dispersants on the cure characteristics, crosslink density and physico-chemical properties of NBR composites were explored. The additives used, especially the ionic liquid and surfactant, effectively improved the dispersion of HAP in the NBR matrix. The amount of HAP and the dispersant used strongly affected the cure characteristics and crosslink density of NBR. The optimal vulcanization time significantly increased with HAP content and was pronouncedly reduced when ionic liquid and surfactant were applied. In addition, ionic liquid and surfactant significantly lowered the onset vulcanization temperature and improved the crosslink density and hardness of the vulcanizates while impairing their elasticity. HAP and dispersants did not significantly affect the damping properties or chemical resistance of NBR vulcanizates. Above all, application of HAP considerably enhanced the resistance of vulcanizates to thermo-oxidative aging and reduced their flammability compared with the unfilled NBR.

Fabrication of flexible Au microsensors by a simple stamping method for the point-of-care direct detection of trace leucomalachite green

Leucomalachite green (LMG) is the metabolic product of malachite green, which is a common aquaculture antimicrobial known for its high toxicity and long persistence. To date, few reports on the direct detection of LMG using electrochemical point-of-care (POC) sensors have been published. In the present work, flexible gold (Au) microsensors were fabricated from nanometer-thin Au leaves for the first time on different substrates, such as polyethylene terephthalate, thermoplastic polyurethane, silicone, polyvinyl chloride wristbands, and nitrile gloves, through simple hot stamping. The entire fabrication process did not involve toxic solvents and complex equipment, and the material cost was only $0.1 per microsensor. The morphology, electrochemical properties, and sensing performance of the microsensors were characterized by scanning electron microscopy, cyclic voltammetry, and differential pulse voltammetry. Benefiting from the excellent catalytic activity and conductivity of Au, the microsensors exhibited outstanding direct sensing capability for LMG with a detection limit of 6.3 nM. Moreover, the microsensors demonstrated excellent recovery rates in real sample analysis, validating their practicality. The technology reported in this work provides a pioneering and effective solution for the sensitive and convenient POC direct detection of LMG and further allows for the fabrication of Au microsensors on different flexible and conformal substrates, offering sensitive solutions for POC detection in environmental, food safety, and healthcare applications.

Revisiting the mechanism of rapid gas decompression failure in silica-reinforced NBR composites: Effect of interfacial phenomena

Sudden pressure drop in elastomers saturated with high temperature-high pressure gas produces a type of failure known as Rapid Gas Decompression (RGD). Understanding the relationship between the RGD and the material behaviour paves the way for better control of the RGD. It is the aim of the present work to study the effect of rubber-silica interfacial phenomena on the RGD resistance of nitrile butadiene rubber (NBR) composites. By grafting various degrees of a long-chain monofunctional silane onto the silica surface, composites having distinct levels of filler-induced mobility restrictions, and also controlled levels of interface strength were prepared. Also, to find the underlying mechanism responsible for controlling the RGD failure, an analysis of silica morphology, the cavitation strength, and the tear strength was performed for the composites. The RGD resistance was assessed under mild (70 MPa) and severe (cyclic test, 150 MPa) testing conditions using carbon dioxide gas. The obtained trend of the RGD damage was roughly correlated to the cavitation test, showing a higher resistance for the silica system having high filler-polymer interaction and bound rubber. It was suggested that the trend of RGD is more complicated to fully capture by a single physico-mechancial mechanism. Alternatively, inspired by the theory of fracture mechanics, it was suggested that the RGD can be better realized if the factors governing the driving force of RGD damage and the factors responsible for the resistance against the RGD are separated.

Molecular Dynamics Simulation and Experimental Study of Friction and Wear Characteristics of Carbon Nanotube-Reinforced Nitrile Butadiene Rubber

Nitrile butadiene rubber (NBR) and its various composite materials are widely employed as friction materials in mechanical equipment. The use of carbon nanotube (CNT) reinforcement in NBR for improved friction and wear characteristics has become a major research focus. However, the mechanisms underlying the improvement in the friction and wear characteristics of NBR with different CNT contents remain insufficiently elucidated. Therefore, we conducted a combined analysis of NBR reinforced with varying CNT contents through molecular dynamics (MD) simulations and ring–block friction experiments. The aim is to analyze the extent to which CNTs enhance the water-lubricated friction and dry wear properties of NBR and explore the improvement mechanisms through molecular chain characteristics. The results of this study demonstrate that as the mass fraction of CNTs (0%, 1.25%, 2.5%, 5%) increases, the water-lubricated friction coefficient of NBR continuously decreases. Under water-lubricated conditions, CNTs improve the water storage capacity of the NBR surface and enhance lubrication efficiency. In the dry wear state, CNTs help reduce scratch depth and dry wear volume.

Electrical and mechanical behaviors of rubber composites based on polar elastomers with incorporated Cu-based alloy

Dielectric elastomers with conducting inorganic fillers offer a wide range of uses, including capacitive energy storage, elastomer sensors, actuators, and many more. In this approach, low dielectric loss and high dielectric constant may be made possible by ternary composites that use metal alloy components as reinforcing fillers. Here, Cu-based alloy was added to acrylonitrile-butadiene rubber (NBR) to produce ternary rubber composites. Unfortunately, the Cu–Al–Zn alloy’s material incompatibility with the rubber matrix typically leads to phase separation, void formation, and particle aggregation, all of which have a dramatic negative impact on performance. Using 3-(trimethoxysilyl)propyl methacrylate as a coupling agent, Cu–Al–Zn alloy particles were uniformly dispersed onto the NBR rubber matrix through surface modification. By using scanning electron microscopy, the appropriate reinforcement of modified Cu-based alloy particles into NBR was carefully examined. The effect of modified Cu–Al–Zn alloy loading on the swelling behavior of the composite was also investigated. The findings show that the shape and dispersion state of modified Cu–Al–Zn alloy were important for the dielectric characteristics of the NBR compounds. By adding reinforced modified Cu-based alloy to the NBR matrix, mechanical characteristics were significantly improved. The uniform dispersion of modified Cu–Al–Zn alloy particles and strong interfacial compatibility with rubber matrix are the reasons for the outstanding performance of NBR composites, which suggests high-performance dielectric composite.

Features of structural formations in butadiene-nitrile rubber films under the action of a directed electric field

Features of structural formations in butadiene-nitrile rubber films under the action of a directed electric field