Hydrogenated Nitrile Butadiene Rubber Research Articles

Evaluation of rapid gas decompression (RGD) resistance of sealing materials for hydrogen-doped pipeline valves

Abstract With the rapid development of hydrogen-doped natural gas pipelines, the evaluation of the applicability of hydrogen to natural gas pipeline systems is bound to gradually involve all aspects of natural gas pipelines. Targeted at the non-metallic sealing materials for valves of hydrogen-doped natural gas pipelines, this paper, according to the ISO 23936-2 standard, carried out the rapid gas decompression (RGD) tests of hydrogenated nitrile butadiene rubber (HNBR), fluorine rubber 246 (FKM246) and fluorine rubber 26 (FKM26), and the damage level of cracking failure for the rubber materials in the course of rapid release of gaseous medium was obtained (DL). The mechanical properties and volumetric dissolution rate of the three rubber materials were tested before and after the high-pressure gas mixture treatment, which explains the reason for the cracking failure of the rubber materials during the RGD test. The study obtained the influence law of high-pressure gas mixture with different hydrogen volume fractions on the RGD resistance of HNBR, FKM246, and FKM26, and selected the material with the optimal RGD resistance as FKM26, which can be used as a reference for the selection of sealing materials for the valves of hydrogen-doped natural gas pipelines in engineering.

Harnessing melt processing for the preparation of mechanically robust thermoplastic vulcanizate electrolytes

We report a new type of polymer blend electrolyte based on the principle of thermoplastic vulcanizates (TPV). TPV materials have been extensively used in the automotive and manufacturing sectors. However, to the best of our knowledge, TPV-based electrolytes have yet to be produced. These electrolytes, obtained via melt-processing, combine the high ionic conductivity and processibility of a thermoplastic phase with the improved mechanical strength of a crosslinked elastomeric phase. TPV electrolytes prepared with poly(caprolactone) (PCL) (thermoplastic phase) and hydrogenated nitrile butadiene rubber (HNBR) (elastomeric phase) are presented in this work. These materials deliver promising results in terms of ionic conductivity, electrochemical stability and mechanical strength. Further improvements in ionic conductivity are obtained by doping the TPV electrolyte with a flame-retardant solvent, triethyl phosphate. The crosslinked nature of the TPV allows both mechanical strength and electrochemical stability to be conserved upon doping which is not possible in non-crosslinked polymer blend electrolytes prepared with PCL and HNBR.

An in-situ view cell system for investigating swelling behavior of elastomers upon high-pressure hydrogen exposure

The transition to hydrogen as a clean and efficient energy carrier is impeded by challenges in the compatibility of hydrogen with materials used within hydrogen infrastructure. Elastomers, crucial in sealing components, often exhibit premature failures in high-pressure hydrogen environments due to excessive swelling. This study employs an innovative in-situ view cell system to assess the swelling behavior of hydrogenated nitrile butadiene rubber (HNBR) under various hydrogen conditions. The system, designed to withstand pressures up to 96.5 MPa, incorporates Digital Image Correlation (DIC) for strain measurements and volume estimation. Results reveal non-linear volume increases during depressurization, challenging conventional assumptions. Furthermore, investigations into peak hydrogen pressures and pressure-holding scenarios during decompression highlight complex swelling trends. The introduction of a novel computer vision (CV) method enhances precision in volume estimation, overcoming DIC limitations. The study provides insights into mitigating elastomer swelling, crucial for developing robust materials to support future hydrogen-driven energy systems.

Artificial Neural Network Modeling in the Presence of Uncertainty for Predicting Hydrogenation Degree in Continuous Nitrile Butadiene Rubber Processing

The transition from batch to continuous production in the catalytic hydrogenation of nitrile butadiene rubber (NBR) into hydrogenated NBR (HNBR) marks a significant advance for applications under demanding conditions. This study introduces a continuous process utilizing a static mixer (SM) reactor, which notably achieves a hydrogenation conversion rate exceeding 97%. We thoroughly review a mechanistic model of the SM reactor to elucidate the internal dynamics governing the hydrogenation process and address the inherent uncertainties in key parameters such as the Peclet number (Pe), dimensionless time (θτ), reaction coefficient (R), and flow rate coefficient (q). A comprehensive dataset generated from varied parameter values serves as the basis for training an artificial neural network (ANN), which is then compared against traditional models including linear regression, decision tree, and random forest in terms of efficacy. Our results clearly demonstrate the ANN’s superiority in predicting the degree of hydrogenation, achieving the lowest root mean squared error (RMSE) of 3.69 compared to 21.90 for linear regression, 4.94 for decision tree, and 7.51 for random forest. The ANN’s robust capability for modeling complex nonlinear relationships and dynamics significantly enhances decision-making, planning, and optimization of the reactor, reducing computational demands and operational costs. In other words, this approach allows users to rely on a single ML-based model instead of multiple mechanistic models for reflecting the effects of possible uncertainties. Additionally, a feature importance study validates the critical impact of time and element number on the hydrogenation process, further supporting the ANN’s predictive accuracy. These findings underscore the potential of ML-based models in streamlining and enhancing the efficiency of chemical production processes.

Evaluation of elastomer suitability for CCUS: Chemical compatibility and rapid gas decompression in supercritical CO2

AbstractThe equipment of carbon capture, utilization, and sequestration (CCUS) infrastructure demands a range of elastomers fully compatible with CO2 phases. In this paper, the typical oilfield elastomers, perfluoroelastomer (FFKM), fluoroelastomer (FKM), tetrafluoroethylene propylene elastomer (FEPM), and hydrogenated nitrile butadiene rubber (HNBR), were studied for their chemical compatibility and rapid gas decompression (RGD) in 100% supercritical carbon dioxide (sCO2). At a given test condition, all selected oilfield compounds passed the ISO 23936‐2 acceptance compatibility criteria after 28‐day aging at 100 C and 34.5 MPa in sCO2. After aging, the elongations at break of the FFKM and FEPM compounds increased; tensile strength for FEPM decreased. In contrast to FFKM and FEPM, FKM and HNBR exhibited both lower elongations at break and lower tensile strengths. The moduli of the various elastomers consistently decreased after the sCO2 aging. The RGD testing revealed that all compounds were capable of passing the RGD ISO 23936‐2 criteria. Complementary material analyses by Fourier transform infrared spectroscopy and differential scanning calorimetry along with surface morphology analyses were also conducted to gain additional insight into the suitability of the selected elastomers for sCO2 service.

Optimum design of HNBR and PCR-based isolation system to protect a sensitive article stored in a naval vessel container subjected to shock load

In naval engineering, protecting sensitive articles from shock loads is a major concern, as it may lead to adverse consequences. This paper focuses on the design of a novel Hydrogenated Nitrile Butadiene Rubber (HNBR) and Polychloroprene Rubber (PCR)-based shock isolation system to protect a sensitive article stored in a hollow cylindrical naval vessel container (NVC). Firstly, NVC is modeled as a two-degree-of-freedom lumped parameter model (LPM), wherein isolators made of HNBR and PCR materials are modeled with 5-order polynomial nonlinear stiffness and linear damping. The optimal values of the isolator parameters are obtained using a multi-objective genetic algorithm, and corresponding responses to a shock load are found using MATLAB. Furthermore, a three-dimensional (3D) finite element model (FEM) of the NVC is generated in ABAQUS and subjected to shock loading in a transverse direction to conduct a comprehensive dynamic analysis of the isolation system. In 3D simulation, HNBR and PCR materials are modeled using a hyper-viscoelastic model developed based on experimental test data. The 3D simulation results of the NVC for the optimized design of HNBR and PCR isolators agree with the optimized results of the LPM. Moreover, the proposed HNBR and PCR isolators are very effective in shock reduction.

Hydrogenation of olefinic bonds in nitrile butadiene rubber on single-atom Pd1/CeO2−x catalysts with ultrahigh mass activity and stability

As pivotal high-performance elastomers, hydrogenated nitrile butadiene rubber (HNBR) was commonly manufactured by selective hydrogenation of nitrile butadiene rubber (NBR). Nevertheless, the high cost and poor stability of current noble metal-based catalysts seriously limit their large-scale applications. Herein, we report single-atom Pd supported by oxygen vacancies-rich CeO2−x nanorods (Pd1/CeO2−x) as a novel catalyst for selectively hydrogenating the NBR. As a result of strong interaction between single-atom Pd and CeO2−x support, the electrophilicity of Pd sites, and the nucleophilicity of olefinic bonds in NBR, the Pd1/CeO2−x show a very high hydrogenated degree of 97.6 %, an unprecedentedly high Pd mass activity of 93.9 gNBR gPd−1h−1, and outstanding cycling stability, which considerably outperform those for previously reported catalysts. Therefore, this work will promote the low-cost manufacture of HNBR and the exploration of single-atom catalysts for selective hydrogenation.

In Situ Generation of a Gel Polymer Electrolyte via the Controlled Formation of Ethylene Carbonate in a Poly(ethylene carbonate)‐Hydrogenated Nitrile Butadiene Rubber Solid Polymer Electrolyte

AbstractElectrolytes play an essential role in electrochemical energy storage devices. Liquid electrolytes have good ionic conductivity but tend to be flammable, prompting some of the safety concerns that are associated with these devices. Solid polymer electrolytes (SPEs) are presented as a potential solution to this problem. These materials have higher mechanical stability and can be formulated to be non‐flammable. However, ionic conductivity in solid polymer electrolytes tends to be several orders of magnitude lower than that of liquid electrolytes, significantly limiting device performance making electrolyte safety and performance difficult to optimize simultaneously. However, gel electrolytes which combine lower flammability, higher mechanical strength, and adequate ionic conductivity may present a solution to this challenge. To this end, the melt processing of hydrogenated nitrile rubber (HNBR) with poly(ethylene carbonate) (PEC) followed by the in situ formation of ethylene carbonate (EC) is reported. Conversion of PEC to EC is confirmed via NMR spectroscopy. Electrochemical testing reveals improved ionic conductivity following the conversion of the solid polymer electrolyte to the gel polymer electrolyte. Improvements in ionic conductivity, relative to the initial SPE, are attributed to decreased salt‐polymer interactions in favor of salt‐EC interactions as observed via differential scanning calorimetry, Fourier transform infrared, and nuclear magnetic resonance spectroscopy.

Characterization and Analysis of Corrosion Resistance of Rubber Materials for Downhole Tools in a High-Stress Environment with Coupled H2S-CO2.

In the process of constructing deep natural gas wells in Sichuan and Chongqing, gas wells encounter various technical challenges such as high temperature, high pressure, and a corrosive environment containing H2S and CO2. The corrosion of rubber materials in these acidic environments can easily lead to seal failure in downhole tools. To better investigate the corrosion resistance of rubber materials in acidic environments, we utilized a dynamic cyclic corrosion experimental device capable of simulating the service conditions experienced by downhole tools under high-temperature, high-pressure multiphase flow. Corrosion-resistance tests were conducted on fluororubbers (FKM) 1, 2, 3, and HNBR (hydrogenated nitrile-butadiene rubber) under acidic conditions (80 °C and 160 °C), along with sealing corrosion tests on O-rings. These tests aimed to analyze the mechanical properties, hardness, and corrosion resistance before and after exposure to acid media as well as the sealing performance of O-rings. Ultimately, our goal was to identify suitable rubber materials for acidic pressure environments. Experimental results revealed that all four types of rubber exhibited decreased elongation at break after undergoing corrosion testing; however, fluororubber 3 demonstrated significant susceptibility to temperature effects while the other three types showed minimal impact from temperature variations. Fluororubber 1 and fluororubber 3 displayed substantial deformation levels whereas mechanical properties greatly deteriorated for fluororubber 2. Overall, HNBR showcased superior comprehensive performance.

Molecular chain orientation and mechanical properties of hydrogenated nitrile-butadiene rubbers with different acrylonitrile content and crosslink density

A study of the thermal and mechanical properties, as well as the molecular chain orientation of sulfur-vulcanized hydrogenated nitrile-butadiene rubber (HNBR) with acrylonitrile (ACN) content of 34 and 36 wt% and different crosslink density is presented. The objective is to establish the relationships between structural changes during stretching and the tensile and elastic behavior of HNBR having different chain microstructure. The (vulcanized) HNBR samples are amorphous at room temperature with glass transition temperatures that increase with increasing ACN content and crosslink density. The samples do not exhibit strain-induced crystallization. Stretching at room temperature only induces orientation of the amorphous segments along the stretching direction, which contributes to improved tensile strength, strain-hardening, and toughness, while preserving excellent elastic recovery of the rubbers. Precise correlations are established between the degree of orientation of the amorphous chain and the deformation in the framework of the affine deformation model of rubber elasticity.

The Springback Effect in Pre-Densified Sulfidic Solid Electrolyte/Binder-Sheets and Their Implication as Separators in All-Solid-State Batteries – a First Approach

All-solid-state batteries (ASSBs) are expected to revolutionize the Li-ion battery landscape thanks to multiple benefits, such as improving both intrinsic safety and potentially enabling high energy anode concepts.[1,2,3] Amongst the variety of possible solid electrolyte (SE) materials for ASSBs, sulfidic electrolytes are considered particularly advantageous, as they possess high ionic conductivities and beneficial mechanical plasticity, allowing their pre-densification by uniaxial cold pressing at high fabrication pressures (p fab).[4] However, one bottleneck of sulfidic ASSBs compared to conventional liquid-electrolyte batteries is the necessity of a certain operating pressure to provide/maintain an intimate mechanical contact between the various materials during materials characterization measurements (e.g., SE conductivity measurements) and/or battery cycling. For these, a special cell setup is required that is hermetically sealed and facilitates a defined and, ideally, variable application of different compressions (operating pressure, p oper) on the sample/cell stack.[5] Typically, ASSB characterization cells possess a defined circular geometry, whereby the components are placed in an inert polymer containment (e.g. a PEEK tube) and are electrically contacted via metal dies.[2,5,6] However, a problem which is often neglected in the literature is the poor solid-solid contact of pre-densified SE pellets (done at a high p fab) and mechanically hard current collector dies to contact the sample for impedance measurements. This leads to impedance artifacts and potentially inaccurately determined solid electrolyte Li+-ion conductivities (σ Li).[2] In this contribution, we firstly describe a novel ASSB cell setup enabling the artifact-free measurement of the ionic conductivity of pre-densified SE-binder sheets in rigid cell matrices. By applying this setup, we could decouple effects from fabrication pressure and operating pressure, providing the basis for determining the correlation between the SE separator porosity and its Li+-ion conductivity, comparing it to the correlations predicted by the Bruggeman equation.We use sheet-type separators consisting of Li6PS5Cl (LPSCl) solid electrolyte and different amounts and types of binder, such as hydrogenated nitrile butadiene rubber (HNBR) and polyisobutylene (PIB), prepared by a slurry-based process.[5] By means of potential-controlled electrochemical impedance spectroscopy (PEIS), the impact of different p fab and p oper on the Li+-ion conductivity of the LPSCl/binder-sheet separators are investigated. As a result, we show that densifying the SE separator sheets at a high p fab, resulting in a low residual porosity, can be used to increase their conductivity at lower p oper. However, a phenomenon which is not reported in such detail so far, is the sensitivity of the measured σ Li of pre-densified LPSCl/binder-sheet separators regarding the p oper. While for pure pre-densified SE powder pellets only a negligible sensitivity regarding the p oper was observed,[2] scalable pre-densified LPSCl/binder-sheet separators show a strong correlation between p oper and measured σ Li.The extent of this phenomenon can be traced back to a “springback” effect, wherby the release of pressure after fabrication a dense binder-sheet separator leads to an apparent decrease in conductivity. We found a clear trend between the binder amount and the extent of this springback effect in LPSCl/binder-sheets and how this affects σ Li at different p oper. Furthermore, to deepen the knowledge about this springback effect, we also investigated the extent of the springback effect on the type of binder (HNBR vs. PIB) and its molecular weight (PIB OPPANOL N50 vs. PIB OPPANOL N150).Additionally, to fully understand different contributions of the pressures and springback to the overall separator impedance, we used PEIS measurements at a very low temperature (-70°C) and a measurement cell with a negligible stray capacitance to clearly distinguish between SE bulk, grain boundary, and springback effects as well as contact resistances, in the impedance spectra for such LPSCl/binder-sheets.Lastly, we evaluate how the springback effect contributes to an overall full-cell impedance in LiNi0.6Co0.2Mn0.2O2|LiIn half-cells and provide a guideline to overcome contact resistances for pre-densified sheet-type ASSB cell components. Based on our findings, it can be concluded that the springback effect contributes to the overall impedance not only in pure SE impedance measurements, but also in half-cells and cannot be neglected when characterizing slurry-coated SE/binder separators-sheets.[1] J. Janek and W. G. Zeier, Nature Energy, 1, 16141, (2016).[2] J.-M. Doux et al., J. Mater. Chem. A, 8, 5049 (2020).[3] S. Cangaz et al., Adv. Energy Mater., 2001320 (2020).[4] Z. Deng et al., J. Electrochem. Soc., 163, A67 (2015).[5] C. Sedlmeier, T. Kutsch et al., J. Electrochem. Soc., 169, 070508, (2022).[6] W. Zhang et al. ACS Appl. Mater. Interfaces, 9, 17835 (2017). Acknowledgements: This work was carried out as part of the project "Industrialisierbarkeit Festkörperelektrolyte", funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy and also supported by the BMW Group.

Dual Network Co-Crosslinked HNBR Composites with Enhanced Tribological Properties under Water Lubrication

Water-lubricated bearings play a critical role in underwater propulsion systems but are often prone to failure due to mechanical wear and vibration, especially under high loads and prolonged friction. In response to this issue, our study introduces a novel approach: a dual network co-crosslinking strategy utilizing hydrogenated nitrile butadiene rubber (HNBR). This strategy connects the rubber network with the epoxy network through epoxidized Eucommia ulmoides gum. A comprehensive analysis was conducted to assess the resulting composite’s damping, tribological, and mechanical properties. The results show that the material has excellent mechanical, damping, and tribological properties relative to pure HNBR, with a 65.9% increase in the damping temperature domain, a 78.5% increase in tensile strength, a low coefficient of friction of 0.022, and a high resistance to abrasion of 3.87 × 10−6 mm3/Nm. The successful synthesis of HNBR-based composites via the dual network co-crosslinking strategy underscores their potential as a practical solution for improving the reliability and prolonging the service life of water-lubricated bearings.

Effect of carboxyl group introduction and graft modification on the thermal properties and Fe wall adsorption performance of HNBR

Hydrogenated nitrile butadiene rubber (HNBR) has been widely used in petrochemical, aerospace, and other fields for its excellent properties. In this study, molecular dynamics methods were employed to construct molecular models of HNBR and hydrogenated carboxyl butadiene rubber (HXNBR). It was found that the introduction of carboxyl groups significantly enhanced the mechanical properties of the material, whereas the glass transition temperature of the material increased by 9.96% and the thermal conductivity decreased by 17.3%. Subsequently, the grafted hydrogenated carboxylated nitrile butadiene rubber (HXNBR-Rx) model and the HXNBR-Rx/Fe bilayer adsorption model, which incorporate grafting modifications with of C5H11OH, C10H21OH, C15H31OH, C20H41OH and C25H51OH, were constructed. In comparison between their thermal properties and the adsorption properties on the metal walls, we revealed that as the number of grafted side chain carbon atoms increased, both the mechanical properties and the glass transition temperature of the material showed a trend of first decreasing and then increasing, while the thermal conductivity of the material first increased and then decreased. Furthermore, the effect of grafting on the material properties was analyzed at the molecular level in terms of free volume fraction, interfacial interaction energy, and relative atomic concentration. The simulation results can provide some theoretical guidance for optimizing the thermal properties of HNBR materials and the adsorption capacity of the metal walls while maintaining their oil resistance and mechanical properties.

Research on Yeoh-Revised hyperelastic constitutive model considering the volume almost incompressible premise for rubber materials

For the totally incompressible Yeoh (i.e., classic Yeoh) model predicts the equibiaxial tension ( ET) stress lower, this paper proposes the totally incompressible Yeoh-Revised model to improve the prediction of ET stress. First, the fitting expression of the totally incompressible Yeoh-Revised constitutive model was derived under the presumption that fluororubber ( FPM) and hydrogenated nitrile-butadiene rubber ( HNBR) are isotropic and entirely incompressible. Meanwhile, the goodness-of-fit ( R^2) statistic was used to assess the fitting outcomes of the three tension tests data (e.g., single tension ( ST), ET and planar tension ( PT)). Additionally, in order to fit the rubber materials tensile test data more accurately, we suggest a novel hyperelastic constitutive fitting method that takes into account the volume microscopic compressibility of rubber materials. The findings demonstrate that the totally incompressible Yeoh-Revised model's prediction of ET stress has marginally improved which neglecting the rubber materials’ volume microcompressibility, while the almost incompressible Yeoh-Revised model fits the ET stress significantly and accurately, and also enhances the forecast accuracy of overall R^2. Finally, the fitting formula of the almost incompressible constitutive model may be reduced to that of the totally incompressible model if the volume microcompressibility is disregarded, which is beneficial to more accurately forecast the experiment tests of rubber materials tension.

A hyper-viscoelastic constitutive model for elastomers: A case study of hydrogenated nitrile butadiene rubber and polychloroprene rubber

Elastomer materials are widely used as shock absorbers in a variety of practical applications including the automotive, aerospace, marine industries and structures. The straightforward Hooke’s law is insufficient to adequately describe the behavior of elastomeric materials due to their nonlinear elastic and viscous properties. This study proposes a hyper-viscoelastic model to describe the mechanical behavior of Hydrogenated Nitrile Butadiene Rubber (HNBR) 62 Duro shore A and Polychloroprene Rubber (PCR) 55 Duro shore A. Six distinct hyperelastic models—Yeoh, Rivlin, Arruda-Boyce, Mooney-Rivlin, Neo-Hookean, and Ogden— are compared herein to explain the nonlinear elastic behavior of elastomers. While the time-dependent characteristics of the considered materials have been described using the four parameters Generalised Maxwell (GM) model. The material parameters of models are determined using the least square fit (LSF) optimization algorithm from the uniaxial, planar, and stress relaxation test data. The stability and suitability of each hyperelastic model is assessed using the Drucker stability. The accuracy of each model is represented by Root Mean Square Error (RMSE) of curve fitting between theoretical and experimental data. On this basis, the Ogden order three ( N = 3) model and the four-parameter GM models are selected which well agreed with the experimental test data and they are integrated to generate the hyper-viscoelastic constitutive model. In addition, the hyper-viscoelastic model is used to simulate the HNBR and PCR dampers under shock load. The numerically generated response is finally compared with the experimental test result of natural rubber (NR) 60 IRH from the existing literature to confirm accuracy of the proposed model.

Evaluation of Polymer-Coated Carbon Nanotube Flexible Microelectrodes for Biomedical Applications

The demand for electrically insulated microwires and microfibers in biomedical applications is rapidly increasing. Polymer protective coatings with high electrical resistivity, good chemical resistance, and a long shelf-life are critical to ensure continuous device operation during chronic applications. As soft and flexible electrodes can minimize mechanical mismatch between tissues and electronics, designs based on flexible conductive microfibers, such as carbon nanotube (CNT) fibers, and soft polymer insulation have been proposed. In this study, a continuous dip-coating approach was adopted to insulate meters-long CNT fibers with hydrogenated nitrile butadiene rubber (HNBR), a soft and rubbery insulating polymer. Using this method, 4.8 m long CNT fibers with diameters of 25–66 µm were continuously coated with HNBR without defects or interruptions. The coated CNT fibers were found to be uniform, pinhole free, and biocompatible. Furthermore, the HNBR coating had better high-temperature tolerance than conventional insulating materials. Microelectrodes prepared using the HNBR-coated CNT fibers exhibited stable electrochemical properties, with a specific impedance of 27.0 ± 9.4 MΩ µm2 at 1.0 kHz and a cathodal charge storage capacity of 487.6 ± 49.8 mC cm−2. Thus, the developed electrodes express characteristics that made them suitable for use in implantable medical devices for chronic in vivo applications.

Enhanced catalytic performance of Pd-Pt bimetallic alloy nanocatalyst for hydrogenation of nitrile butadiene rubber

Nowadays, the rational design of high-performance catalysts with desirable resistance to metal leaching has become the principal challenge in the hydrogenation of nitrile butadiene rubber. In the present work, the Pd-Pt bimetallic alloy nanocatalyst exhibits an outstanding hydrogenation degree of 99.0%, obviously higher than that of the conventional monometallic Pd/SiO2 catalyst with the same Pd content (92.9%), accompanied by approximately 100% selectivity to C=C bonds. The results reveal that electron transfer from Pt to Pd confirms that the Pd species are in a rich-electron state, which boosts hydrogen activation and improves catalytic activity. Additionally, the incorporation of inactive Pt species promotes the formation of uniformly dispersed Pd-Pt alloy nanoparticles. The incorporation of inactive Pt species can enhance the metal-support interaction, reducing the residual metal content in hydrogenated nitrile butadiene rubber. The current research demonstrates a simple procedure for designing efficient bimetallic catalysts for the hydrogenation of unsaturated elastomer.

Molecular Simulation and Experimental Study on the Damping and Aging Properties of 4010NA/Hydrogenated Nitrile Butadiene/Nitrile Butadiene Rubber Composites

Front Cover: The effects of 4010NA content on the damping and aging properties of hydrogenated nitrile butadiene rubber (HNBR)/nitrile butadiene rubber (NBR) matrix are studied via molecular simulation and experiments. With an increase in the 4010NA content, there is a decrease in the free volume fraction (FFV), attributed to the hydrogen bond network between 4010NA and the HNBR/NBR matrix. This is reported by Meng Song, Qi Qin, and co-workers in article number 2200072.

Molecular Simulation and Experimental Study on the Damping and Aging Properties of 4010NA/Hydrogenated Nitrile Butadiene/Nitrile Butadiene Rubber Composites

AbstractThe effects of N‐isopropyl‐N′‐phenyl‐phenylenediamine (4010NA) content on the damping and aging properties of hydrogenated nitrile butadiene rubber (HNBR)/nitrile butadiene rubber (NBR) (abbreviated as H‐NBR) matrix are studied via molecular simulation and experiments. The effects of 4010NA addition on the damping and aging properties of H‐NBR are analyzed by molecular simulation using solubility parameters (δ), hydrogen bonds, free volume fraction (FFV), binding energy (Ebinding), hydrogen bond dissociation energy (ΔG), and mean square displacement (MSD). The damping, mechanical, and thermo‐oxygen aging properties of the 4010NA/H‐NBR composites are studied experimentally using infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). The results indicate that 4010NA has good compatibility with HNBR and NBR, and the addition of 4010NA can effectively improve the damping properties of H‐NBR. When 4010NA is added at 32 phr, the composite has better damping properties, mechanical properties, and aging resistance, which provides a new insight for the construction of high performance elastomer composites.

The Sealing Effect Improvement Prediction of Flat Rubber Ring in Roller Bit Based on Yeoh_Revised Model.

In a roller bit, the flat rubber ring (FRR) often needs to apply a certain amount of compression to ensure that its rotation and static sealing surfaces can be stably sealed. For the predicted Mises stress, values smaller than the actual Mises stress due to soft single-axis compression (SAC) stress are predicted by the Yeoh (N = 3) model. To more reasonably predict stress under the static compression of the FRR in the roller bit, the sealing effect of the FRR based on the SAC contact stress and the calculated Mises stress was evaluated by the Yeoh_revised model. Based on the assumption that hydrogenated nitrile-butadiene rubber (HNBR) is isotropic and incompressible, first, we derived the fitting formulas for three types of constitutive models and the Jacobi matrix of the Yeoh_revised model and developed hyperelastic constitutive subroutines. Simultaneously, the accuracy of three models (Yeoh, Yeoh_revised and Ogden) was evaluated by the goodness of fit (R2) to data from three kinds of tensile experiment tests. The highest R2 is 0.9771 with the Yeoh_revised model, which merges the advantages of the other two fitting models and effectively improves the Yeoh model’s soft property of SAC contact stress. Additionally, by measuring on-site FRR wear, the maximum Mises stress on the sealing surface calculated based on the Yeoh_revised model is about twice that of the Yeoh model, and the maximum Mises stress on the rotation contact sealing surface is higher than that on the outside (static sealing) surface, which makes the aging of the rotation surface more severe. Thus, it was demonstrated that, on the premise of ensuring FRR sealing contact stress, the Yeoh_revised model can more reasonably predict the sealing effect of the FRR to more precisely calculate Mises stress than the Yeoh model. This also contributes to FRR structure optimization to prolong the service life of the FRR in the roller bit.