Showing papers on "Nitrile rubber published in 2023"
TL;DR: In this article , 1,2-dihydro-2,2,4-trimethylquinoline (antioxidant RD) and carbon nanotubes (CNTs) were introduced into NBR to improve its thermal-oxidative aging performance and reduce its wear.
Abstract: Nitrile butadiene rubber (NBR), a common material used in the stator rubber of screw pumps, usually undergoes severe thermal-oxidative aging and wear at various temperatures and pressures. In this study, 1,2-dihydro-2,2,4-trimethylquinoline (antioxidant RD) and carbon nanotubes (CNTs) were introduced into NBR to improve its thermal-oxidative aging performance and reduce its wear. The thermal-oxidative aging and mechanical and tribological properties of NBR composites with acrylonitrile (ACN) contents of 28%, 33%, and 41% were investigated via molecular dynamics simulations, and the interaction mechanisms of four composites: RD/N28, CNT/RD/N28, CNT/RD/N33, and CNT/RD/N41, were investigated at the atomic level. A three-layer model (Fe–Composites–Fe) was developed to simulate the wear process of the composites. CNT/RD/N41 exhibited better thermal-oxidative aging and tribological properties than those exhibited by CNT/RD/N28 and CNT/RD/N33. This was attributed to an increase in the polar–polar interactions of the nitrile (CN) groups with an increasing ACN content. During friction, a larger frictional force existed between the CNT/RD/N41 molecules, which effectively maintained the stability of the matrix. This study provides a scientific reference for the preparation of high-performance NBR at the microscopic scale, which may extend the service life of screw pumps.
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TL;DR: In this paper , a simple and effective chemo-mechanical devulcanization for waste nitrile rubber (WNBR) was introduced and compared to the mechanical, thermo-chemo-mchanical, and radio-chemmechanic methods.
Abstract: Waste rubbers are environmental pollutants that could not be easily recycled. Devulcanization (i.e. as a reverse process of rubber vulcanization) is considered as a promising method for recycling of rubber wastes. In this study, a simple and effective chemo-mechanical devulcanization for waste nitrile rubber (WNBR) was introduced and compared to the mechanical, thermo-chemo-mechanical and radio-chemo-mechanical methods. The mechanical stress was applied to crumbed waste rubbers using a two roll mill in presence of different chemical agents (i.e. N-cyclohexyl-2- benzothiazole sulfonamide (CBS), tetra methyl thiuram disulfide (TMTD), diphenyl disulfide (DPDS), VitaX and a mixture of VitaX and DPDS). The sheet formation time on two roll mill, crosslink density (CLD) and sol/gel contents of waste rubber powders were measured before and after devulcanization. The devulcanized rubbers were characterized using TGA, DSC and GPC analysis. Finally, the properties of devulcanized nitrile rubber (i.e. the tensile, hardness and curing properties) were evaluated and compared to pristine NBR. It was found that VitaX is the most efficient chemical agent among the chemical agents. It caused 43, 87 and 98% decrement in the sheet formation time of chemo-mechanically, thermo-chemo-mechanically and radio-chemo-mechanically devulcanized samples compared to the mechanically devulcanized NBR, respectively. The samples also showed 24, 33 and 100% increment in the sol content, devulcanization percent and tensile strength compared to the mechanically devulcanized NBR, respectively.
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TL;DR: In this article , the authors report efficacy of zirconia towards property enhancement of a rubber blend comprised of non-polar natural rubber (NR) and polar nitrile rubber (NBR).
TL;DR: In this paper , a lifetime prediction methodology for a downhole HNBR packer was developed based on fundamental material behavior such as viscoelasticity, hyperelasticity and chemical/physical degradation from laboratory aging tests, and finite element analysis.
Abstract: Hydrogenated acrylonitrile butadiene rubber (HNBR) has been widely used in many products that serve as sealing components for downhole operations in the energy industry, especially downhole permanent packers. A reliable methodology needs to be developed to predict operational limits for the elastomer during various tool deployments and operations. These operational limits are mostly based on laboratory life prediction tests derived from industry standards meant for material selection or screening. However, the conventional life prediction method cannot capture the effect of size/shape/stress and adequately predict the sealing performance of an actual elastomeric component under downhole operations. To fill this gap, a lifetime prediction methodology for a downhole HNBR packer was developed based on fundamental material behavior such as viscoelasticity, hyperelasticity, chemical/physical degradation from laboratory aging tests, and finite element analysis. Thereafter, the proposed methodology was used to develop an operational limit for the downhole packer in completion brine, calcium bromide. The results showed that the proposed methodology was not limited to the size or shape of the elastomeric product and can be readily extended to develop a successful operational limit for various elastomeric components in the energy industry.
TL;DR: In this paper , a study of the influence of the mixing mode and curing system on the properties of low temperature and oil resistant rubber based on a composition of butadiene-nitrile rubber (BNKS-18AMN) and ultra-high molecular weight polyethylene (GUR 4113) is presented.
Abstract: The results of a study of the influence of the mixing mode and curing system on the properties of low temperature and oil resistant rubber based on a composition of butadiene-nitrile rubber (BNKS-18AMN) and ultra-high molecular weight polyethylene (GUR 4113) are presented. Different ways of UHMWPE introducing into the rubber compound are considered: mixing before and after the introduction the main ingredients of the rubber compound at temperatures up to 80 °C (below the melting point of UHMWPE) and preliminary high-temperature (160 °C) mixing of rubber and UHMWPE. It was found that the preliminary high temperature mixing of rubber with UHMWPE leads to a decrease in the viscosity of the rubber compound, as well as a reduction in the scorch time and the achievement of an optimum vulcanization but does not lead to significant changes in the physical and mechanical properties and oil resistance of vulcanizates. The study of the influence of the curing system showed the effectiveness of using a combined sulfur-peroxide curing system, which is manifested in the improvement of the technical properties of vulcanizates, which is largely due to an increase in the density of rubber crosslinking through the formation of stronger and more heat-resistant C-C bonds. It has been shown that the best set of technical properties of vulcanizates, including high frost-resistance, physical and mechanical properties, resistance to hydrocarbon environment and retention of properties after thermal exposure, is achieved when using the sulfur-peroxide combination S/DCP – 1/2.
TL;DR: In this paper , the influence of the type of vulcanization accelerator and the quantitative composition of the curing system on the cure characteristics, morphology of elastomer network, crosslink density and physico-chemical properties of acrylonitrile-butadiene rubber (NBR) composites was studied.
Abstract: The goal of this work is to study the influence of the type of vulcanization accelerator and the quantitative composition of the curing system on the cure characteristics, morphology of elastomer network, crosslink density and physico-chemical properties of acrylonitrile-butadiene rubber (NBR) composites. Sulfur curing systems are investigated, which consist of various types of accelerators, that is, sulfenamide, guanidine and thiuram, applied in various proportions to sulfur. The type of accelerator and the sulfur/accelerator ratio significantly affect both the cure rate and the structure and number of crosslinks resulting from the vulcanization. The highest cure rate and the lowest content of polysulfidic crosslinks are exhibited by rubber composites with efficient (EV) curing systems due to the highest content of accelerators compared to semi-efficient (SEV) and conventional (CV) systems. The structure of crosslinks strongly affect tensile properties and hardness of the vulcanizates as well as their solvent resistance, thermal stability and resistance to thermo-oxidative aging.
TL;DR: In this article , polypropylene (PP)/carboxylated acrylonitrile butadiene rubber (XNBR) binary blends were prepared with the elastomer component dosed in its suspension (latex) form into the polymer matrix during melt compounding.
Abstract: Abstract In this work, polypropylene (PP)/carboxylated acrylonitrile butadiene rubber (XNBR) binary blends were prepared with the elastomer component dosed in its suspension (latex) form into the polymer matrix during melt compounding. For this purpose, samples containing 0-20 wt.% rubber were prepared using two different PP grades as matrices with lower and higher viscosity. Analogous reference samples with the same composition were also fabricated using traditional melt mixing by introducing the rubber in its dry, bulk form in order to analyze the efficiency of the latex route. Mechanical, thermomechanical and morphological analyses were used to investigate the structure-property relationships of the blends. Based on the SEM images the average domain size of the dispersed XNBR domains became markedly smaller when the rubber was introduced in its suspension form into the PP. Based on the Charpy impact tests and the tensile test results, the decreased rubber domain size led to improved ductility and toughness. The improvement was more prominent when the difference between the viscosity of the PP matrix and the XNBR rubber was higher.
TL;DR: In this article , a novel potassium methyl siliconate (PMS) was employed as a nano-type antioxidant for acrylonitrile-butadiene rubber (NBR).
Abstract: In this work, novel potassium methyl siliconate (PMS) was employed as a new nano-type antioxidant for acrylonitrile-butadiene rubber (NBR). NBR/PMS composites were produced by incorporating various contents of the prepared compound as anti-ageing agents (PMS) to improve the heat resistance of these composites. Potassium methyl siliconate (PMS) was prepared, and its chemical structure was confirmed by different elemental analyses. The curing properties, filler dispersion, thermo-oxidative ageing test, mechanical properties, FTIR, and TGA of the NBR/PMS composites were evaluated. It was detected by TEM images of PMS. The particles had a rhombic shape, and the particle size ranged from 1.23 nm to 7.84 nm. PMS could successfully promote the interfacial interaction between rubber and filler and the uniform dispersion of silica particles into the NBR matrix. As a result, the mechanical characteristics of the NBR/PMS composites were significantly improved, and they were superior to those of the NBR/TMQ composites with similar filler contents. Furthermore, the crosslinking density of the NBR composites was reduced after adding PMS (an antioxidant), which had a great effect on the mechanical properties. The results exhibited that PMS dramatically enhanced the solvent extraction resistance and the thermo-oxidative ageing resistance of NBR/silica composites more efficiently than TMQ. Overall, this work extended the application scope of PMS to develop novel and effective antioxidants for elastomers.
TL;DR: In this article , an efficient and environmentally friendly strategy was demonstrated for enhancing the interfacial interaction between nitrile-butadiene rubber (NBR) and montmorillonite (MMT) nanocomposites.
TL;DR: In this article , three types of anti-corrosion coatings were prepared on 5083 Al alloy by a simple smearing method, and the coatings are based on neat epoxy resin by introducing different amounts of graphene oxide, methyl methacrylate/nitrile rubber/graphene oxide fillers.
Abstract: Graphene oxide has a wide application prospect as filler due to its excellent physical blocking, coating reinforcement, and cathodic protection properties. However, graphene oxide is highly susceptible to agglomerative reunions. Three types of anti-corrosion coatings were prepared on 5083 Al alloy by a simple smearing method. The coatings are based on neat epoxy resin by introducing different amounts of graphene oxide, methyl methacrylate/nitrile rubber, and methyl methacrylate/nitrile rubber/ graphene oxide fillers. Thermogravimetric analysis (TGA) results show that methyl methacrylate/nitrile rubber/graphene oxide fillers enhance the thermal stability of the epoxy resin-based coatings. The SEM morphology shows the well-dispersed methyl methacrylate/nitrile rubber/graphene oxide in the coating. The 2 and 1 wt% methyl methacrylate/nitrile rubber/graphene oxide coating exhibits excellent mechanical properties and outstanding anti-corrosion properties, respectively. At 1 wt%, the OCP of the coating is −0.21 V. Additionally, the coating exhibits great anti-corrosion performance after immersion for 196 h. Compared to the pristine coating and methyl methacrylate/nitrile rubber coatings, the methyl methacrylate/nitrile rubber/graphene oxide coatings show better thermal stability, mechanical properties and anti-corrosion properties. The methyl methacrylate/nitrile rubber fillers degrade the thermal stability and anti-corrosion protection and do not affect mechanical properties. Compared with graphene oxide coatings, the surface of methyl methacrylate/nitrile rubber/graphene oxide coatings is smoother with better dispersion, possessing better mechanical and anti-corrosion properties though only a fewer amounts of graphene oxide were filled in epoxy resin. The better corrosion resistance of the coating can be attributed to the synergistic effect of a physical barrier and a coulomb block.
TL;DR: In this paper , the aging behavior and degradation mechanism of nitrile rubber (NBR) under free and compression states were investigated in simulated air and hydraulic oil environments at various elevated temperatures.
Abstract: The aging behavior and degradation mechanism of nitrile rubber (NBR) under free and compression states were investigated in simulated air and hydraulic oil environments at various elevated temperatures. The variations in the crosslinking density, volatile components and the chemical structure of NBR during aging were studied using equilibrium swelling testing and dynamic mechanical analysis (DMA), pyrolysis-gas chromatography–mass spectrometry and attenuated total reflection-Fourier transform infrared spectroscopy. The migration of additives in different media and the crosslinking density of NBR aged in different conditions were compared. The tensile strength, DMA, and thermogravimetric analysis results were consistent with the changes in the crosslinking density of NBR and the migration of additives. Four effects of the simulated hydraulic system on the thermal aging of NBR were examined. Both the compression stress and the oil medium slowed the aging of NBR. The results can provide new insights into the use of NBR products in lubricating oil environments and NBR lifespan prediction in hydraulic working conditions.
TL;DR: In this article , the authors aimed at producing polyurethane dispersion (PUD)/carboxylated nitrile butadiene rubber (XNBR) blends without using accelerators and sulfur.
Abstract: This study is aimed at producing polyurethane dispersion (PUD)/carboxylated nitrile butadiene rubber (XNBR) blends without using accelerators and sulfur. The PUD/XNBR (at blending ratios of 90:10, 80:20, 70:30, and 60:40) was prepared using coagulation and latex dipping technology. The result demonstrated that increasing XNBR in the PUD/XNBR blends increased the zeta potential of the blends up to −71.8 mV. Fourier transform infrared (FTIR) studies show hydrogen interaction bonding exists between XNBR and PUD, which significantly impacts the degree of phase mixing, degree of phase separation and relative change of hard segment separation of the PUD. The surface energy of the PUD blend is reduced from 34.68 ± 0.23 to 22.28 ± 0.63 mJ−2 with increasing XNBR loading. The presence of XNBR had increased the polar component of the surface energy, but a further increase of the XNBR amount to more than 20% had reduced the tensile strength. Overall, loading 20% of XNBR (PUD80) showed the best performance by having an improvement in tensile strength compared to pristine PUD.
TL;DR: In this paper , the relationship between o-ring swelling of sustainable aviation fuel (SAF) components, model compounds, and various blends in nitrile rubber compared to conventional fuel swelling was explored.
Abstract: : The commercial aviation sector is seeking to reach net zero CO 2 emissions by 2050, with sustainable aviation fuel (SAF) being the most important lever. However, SAF is currently limited by ASTM specifications to a maximum of 50%v blending with conventional jet fuel. One reason for the current blend limit is motivation to maintain o-ring swelling consistent with 100% petroleum fuel. This work explores the relationships between o-ring swelling of SAF blend components, model compounds, and various blends in nitrile rubber compared to conventional fuel swelling. Specifically, optical dilatometry measurements were used to gather swell propensity data for 39 different hydrocarbon dopants at 8%v in an iso-alkane solution, 4 dopants at 7 different concentrations, and 19 different fuels or fuel blends. This study also highlights the advantages of using swell measurements, such as those employed here, as a quality control metric instead of the current 8%v aromatics requirement. Notably, the potential is shown to maintain swelling in the conventional fuel range with fuels composed of less than 8%v aromatics.
TL;DR: In this article , the degradation behaviors and mechanism of nitrile butadiene rubber (NBR) after prolonged exposure to C5F10O are studied. And the effect of this interaction on the elasticity of NBR is calculated through molecular dynamics simulations.
Abstract: C5F10O is a promising insulating medium in the manufacturing of environmentally friendly gas-insulated switchgears (GISs). The fact that it is not known whether it is compatible with sealing materials used in GISs limits its application. In this paper, the deterioration behaviors and mechanism of nitrile butadiene rubber (NBR) after prolonged exposure to C5F10O are studied. The influence of C5F10O/N2 mixture on the deterioration process of NBR is analyzed through a thermal accelerated ageing experiment. The interaction mechanism between C5F10O and NBR is considered based on microscopic detection and density functional theory. Subsequently, the effect of this interaction on the elasticity of NBR is calculated through molecular dynamics simulations. According to the results, the polymer chain of NBR can slowly react with C5F10O, leading to deterioration of its surface elasticity and loss of inside additives, mainly ZnO and CaCO3. This consequently reduces the compression modulus of NBR. The interaction is related to CF3 radicals formed by the primary decomposition of C5F10O. The molecular structure of NBR will be changed in the molecular dynamics simulations due to the addition reaction with CF3 on NBR’s backbone or branched chains, resulting in changes in Lame constants and a decrease in elastic parameters.
TL;DR: In this article , the effects of polyamide elastomer (PAE) content on the overall crosslink densities of acrylonitrile-butadiene rubber (NBR) was studied.
Abstract: Polyamide elastomer (PAE) is a novel material which may improve the performances of acrylonitrile-butadiene rubber (NBR). This work uses equilibrium swelling and rheological apparatus to study the effects of the PAE content on the overall crosslink densities of NBR/PAE vulcanizate. The presence of PAE significantly increased the overall crosslink density. During the aging stage, the overall crosslink density first increased and then decreased with increasing aging temperature from 25 to 150°C. There was a linear relationship between the tensile strength with the overall crosslink density of the NBR/PAE vulcanizate. Oil resistance of the NBR/PAE vulcanizate was improved with increasing PAE content.
01 Apr 2023
TL;DR: In this paper , the surface modification with 1,1,2-trifluoro-1, 2,2,2 trichlorethane improved the properties of nitrile-butadiene rubber.
Abstract: This study investigated novel methods for treating the surface of nitrile-butadiene rubber to enhance its stability and resistance to thermal oxidation and aggressive media. The rubber surface was modified using 1,1,2-trifluoro-1,2,2-trichlorethane. The study found that the duration of the modification strongly affected specific properties of the rubbers examined. It was observed that surface modification with 1,1,2-trifluoro-1,2,2-trichlorethane improved the properties of nitrile-butadiene rubber. Subsequently, the impact of the modification duration on morphology, thermal resistance, and chemical resistance was presented.
TL;DR: In this article , the NBR/clay10/CSP20 nanocomposite cured for 70 min with tensile strength of 37.4 MPa and elongation at break of 354% which was far beyond the ordinary rubber/Clay nanocompositionites.
Abstract: The conventional covalent crosslinking has been commonly utilized in rubber/clay nanocomposite, but stronger crosslinking bonds such as coordination crosslinking should be introduced to further improve the mechanical properties. Herein, we first prepared the nitrile butadiene rubber (NBR)/clay nanocompound via gel compounding method, and then copper sulfate pentahydrate (CSP) was introduced to prepare NBR/clay/CSP nanocomposites via the coordination crosslinking. The nanocomposites with higher CSP content and more curing time exhibited higher crosslinking density and glass transition temperature, because more rubber chains were immobilized by the CSP particles. Similar effect on mechanical properties was found by increasing the CSP content and by prolonging the curing time. By optimizing the curing time, the best mechanical properties was achieved for the NBR/clay10/CSP20 nanocomposite cured for 70 min with tensile strength of 37.4 MPa and elongation at break of 354%, which was far beyond the ordinary rubber/clay nanocomposites.
TL;DR: In this paper , NBR-Graphene oxide (GO) was chemically modified by 3-aminopropyl)triethoxysilane to reinforce NBR and NBR/MGO composites.
Abstract: Graphene oxide (GO) was chemically modified by 3-aminopropyl)triethoxysilane. The modified GO (denoted as MGO) was used to reinforce nitrile butadiene rubber (NBR). The occurrence of the chemical modification was confirmed by various characterization techniques. NBR/GO (or MGO) composites were prepared by a mechanical blending process. Their mechanical and tribological properties of NBR-GO/MGO nanocomposites were investigated. The NBR/MGO composites exhibited superior performances compared to their NBR/GO counterparts over the GO (or MGO) range of 1–5 wt%. The tensile strength of the NBR/MGO (1phr) was increased by 43.7% and 30.3%, and the abrasion loss was decreased by 59.3% and 58.9% with regard to the NBR and NBR/GO composite, respectively. The morphologies of the fractured and worn surfaces of the composites were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy to reveal the reinforcement mechanisms of MGO. The pull-out behavior of the GO or MGO from the NBR matrix and the interlayer peel-off behavior of the GO or MGO were described by molecular dynamic simulations. The stress required to pull the MGO off the NBR matrix was 121.2% that for the GO, while that of the interlayer peel-off for the MGO was 36.7% that for the GO. This explains the fact that the MGO was able to be better dispersed in the NBR than the GO and consequently better reinforce the mechanical and tribological properties of the latter.
TL;DR: In this paper , the effects of nanokaolin (NK) on the tensile and chemical properties of carboxylated nitrile butadiene rubber (NBR)/polyurethane (PU) latex blends were investigated.
Abstract: The demand for gloves (e.g., disposable gloves, medical gloves) is increasing due to the Coronavirus disease 2019 (COVID-19) pandemic. Stability in the supply chain in the glove industry is important, and thus strategies are used to solve the problem of the shortage of nitrile gloves. The blending of nitrile butadiene rubber (NBR) with polyurethane (PU) and the use of the nanocomposite concept is among the feasible approaches. The present study aims to investigate the effects of nanokaolin (NK) on the tensile and chemical properties of carboxylated nitrile butadiene rubber (NBR)/polyurethane (PU) latex blends. Three different loadings of NK (10, 20, and 30 parts per hundred rubber) were added to the NBR/PU (at a blending ratio of 85/15). The zeta potential showed that all the NBR compounds exhibit good colloidal stability. The incorporation of NK increased the crosslink density and tensile strength of the NBR/PU latex blends. The highest tensile strength was achieved when the NK loading was 20 phr. All the NBR blends and nanocomposites (NBR/PU-based) possess tensile properties that fulfill the requirements for glove application. The chemical resistance of NBR compounds was increased by the incorporation of NK due to the higher crosslink density and barrier properties contributed by the NK.
TL;DR: In this article , the effect of the varying ratios of hybrid CB/PKSBc on the rheological properties, abrasion resistance, and hardness of XNBR composites was investigated.
Abstract: With the rapid development of the palm oil-related industry, this has resulted in the high production of palm oil waste. The increasing amount of palm oil waste has become an alarming issue in which researchers have carried out studies that this palm oil waste has the potential to be used as a biomass source. Carbon black (CB) is the most preferred reinforcing filler in the rubber industry but it has a disadvantage where CB is carcinogenic and a petroleum-based product. Hence CB is less sustainable. Palm kernel shell (PKS) derived from palm oil waste can be turned into palm kernel shell biochar (PKSBc) which can potentially be a value-added, sustainable biofiller as reinforcement in rubber composites. In this study, PKSBc is hybridized with CB (N660) at different loading ratios to be filled in carboxylated nitrile butadiene rubber (XNBR). This study aims to elucidate the effect of the varying ratios of hybrid CB/PKSBc on the rheological properties, abrasion resistance, and hardness of XNBR composites. In this study, both CB and PKSBc are incorporated into XNBR and were then cured with sulphur. The composites were prepared by using a two-roll mill. Different compositions of hybrid CB/PKSBc were incorporated. The rheological properties and physicomechanical properties, such as abrasion resistance and hardness of the vulcanizates, were investigated. Based on the results, as the loading ratio of PKSBc in hybrid CB/PKSBc increases, the cure time decreases, and the cure rate index increases. The abrasion resistance and hardness values of vulcanizates were maintained by the high loading of PKSBc which was due to the porous structure of PKSBc as shown in the morphological analysis of PKSBc. The pores of PKSBc provided mechanical interlocking to reduce volume loss and maintain the hardness of vulcanizates when subjected to force. With this, PKSBc is proven to be a semi-reinforcing filler that could not only act as a co-filler to existing commercialized CB, but PKSBc could also fully substitute CB as reinforcement in rubber, specifically XNBR as it is able to provide high abrasion resistance and hardness to the rubber composites. This would mean the performance of PKSBc is comparable with CB (N660) when it comes to maintaining the physicomechanical properties of XNBR composites in terms of abrasion resistance and hardness. Therefore, this approach of using eco-friendly filler derived from palm oil agricultural waste (PKSBc) can reduce the abundance of palm oil waste, be a sustainable alternative to act as a co-filler in hybrid CB/PKSBc to decrease the usage of CB, and helps to enhance the quality of existing rubber-based products.
TL;DR: In this paper , two parts of layered double hydroxide (LDH) are added to NBR to improve the tensile elongation at break, tear strength, and 100% modulus stress.
Abstract: 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.
TL;DR: In this article , a gel-compounding method was utilized to prepare nitrile butadiene rubber (NBR)/clay nanocomposite, and then a hindered phenol antioxidant, triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate (AO-245) with various contents, was mechanically blended to enhance the interactions in the Nanocomposites.
Abstract: Clay modification by organic ammonium salts has been widely introduced in rubber/clay nanocomposites, but it is inapplicable in the polar rubbers to achieve high performance due to bad dispersion and poor compatibility. In this work, gel-compounding method was utilized to prepare nitrile butadiene rubber (NBR)/clay nanocomposite, and then a hindered phenol antioxidant, triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate (AO-245) with various contents, was mechanically blended to enhance the interactions in the nanocomposites. The elongation at break increases while the Shore A hardness, permanent set and stress at 100% or 300% strain decrease by adding AO-245 into the nanocomposites. By adding only 5 phr AO-245 in the nanocomposite, the tensile strength and elongation at break increased from 18.3 MPa and 521% to 20.5 MPa and 646%, respectively, which resulted from the repeated destruction/construction of the hydrogen bonds between AO-245 and NBR. At high AO-245 content, both clay networks and AO-245 aggregate networks coexist in the nanocomposite, and the excess AO-245 in the NBR matrix can form a separated phase leading to a new internal friction peak.
TL;DR: In this article , an efficient curing strategy using multifunctional epoxides, which undergo a nucleophilic ring opening reaction across the free COOH groups of a carboxylated nitrile butadiene rubber (XNBR), was pursued.
Abstract: Herein, we pursue an efficient curing strategy using multifunctional epoxides, which undergo a nucleophilic ring opening reaction across the free COOH groups of a carboxylated nitrile butadiene rubber (XNBR). Following a prevulcanization protocol, we cure the rubber in the latex phase at 60°C. Thin films are then prepared by using a conventional coagulant dipping process, in which the final cure degree of the elastomer is reached during drying (postvulcanization). In a comprehensive approach, cure kinetics, tensile properties, and crosslink density of the thin elastomer films are studied as a function of the functionality and concentration of the applied crosslinker. The results clearly show that films with high tensile strength (39 MPa) are obtained without prevulcanization. Stability tests reveal that the shelf life of the latex formulations is limited to less than 1 day due to hydrolysis reactions of the epoxy groups of the water-soluble crosslinker. However, the storage stability can be extended to several days if nonwater-soluble epoxy crosslinkers are applied. The decent shelf life together with the fast cure rates and excellent mechanical properties make epoxy crosslinking a promising curing strategy for preparing dipped rubber gloves without hyperallergenic accelerators used in classical sulfur vulcanization.
TL;DR: In this article , the damping properties of reduced graphene oxide/nitrile butadiene rubber (RGO/NBR) composites were analyzed by combining molecular dynamics simulation and experiments.
Abstract: By combining molecular dynamics (MD) simulation and experiments, this work describes a systematic, quantitative study on the nanoscale damping of nitrile butadiene rubber (NBR) by adding graphene oxide (GO) with different oxidation degrees. Using MD simulation, the proposed two-component solubility parameters predict that GO2 (O wt %, 17.05%) and NBR have excellent thermodynamic compatibility. GO2/NBR system shows the largest molar concentration of intermolecular hydrogen bonds and the lowest free volume fraction and mean square displacement. GO2 presents a strong adsorption effect on NBR polymer chains. Meanwhile, the green preparation method of reduced graphene oxide has been developed for improving damping properties of reduced graphene oxide/nitrile butadiene rubber (RGO/NBR) composites. The prepared RGO/NBR composites with tailor-made oxidation degrees are adopted to validate the theoretical prediction by MD simulation. Fourier transform infrared spectroscopy verifies that hydrogen bond networks exist between GO and NBR polymer chains. Two main factors, the number of intermolecular hydrogen bonds and the degree of wrinkles of GO sheets dominate the damping performance of the composites. The results indicate that when the GO oxidation degree is about 17.05%, the damping capability of GO/NBR composites is maximum improved. These results pave the way for the environmentally modifying interface to design high performance GO/rubber composites.
TL;DR: In this article , an experimental study on the tracking and erosion properties of NBR with [0, 0.5, 1, 1.5 and 3 part per hundred part of rubber (Phr.)] titanium dioxide (TiO2) nanoparticles is presented.
Abstract: Occurrence of tracking and erosion on surface of polymer insulator leads to breakdown of these materials and has negative impact on their quality. Contaminants forms surface layer on insulators and chemically interact with it. This effect reduces smoothness of surface insulator and forms conducting paths. It allow passage of higher values of leakage current and cause ionization of field around insulator and rise temperature of surfaces, this leads to formation phenomenon of tracking and erosion.it cause deterioration, ageing and collapse of insulator, which affect safety of electric system. How to significantly enhance the tracking and erosion properties of nitrile butadiene rubber (NBR) are a major topic in electric insulators. With a view to enhancing the tracking and erosion properties of NBR used in power systems, nanoparticles are usually added to pure materials to enhance their electrical and physical properties. This work deals with experimental studies on tracking and erosion properties on NBR loaded with [0, 0.5, 1, 1.5, and 3 part per hundred part of rubber (Phr.)] titanium dioxide (TiO2) nanoparticles. Composite materials have been experimentally tested by inclined plane test (IPT) according to the ASTM D2303 standard. When it is necessary to explore a new insulating material, the inclined plane test is used. This is because IPT is used to evaluate the properties of laboratory modified polymers under different voltages. The times to track during the test were recorded. Data processing, analog to digital systems, and data acquisition have been used to measure leakage current passing through samples. When comparing result of leakage current measurements, it was noted that its value was lower for modified samples compared to virgin samples. This positive effect indicates to enhancement of NBR as a result of formation of stable chemical bonds.