Tribological testing of peroxide cured HNBR with different MWCNT and silica contents under dry sliding and rolling conditions against steel

The sliding, and rolling friction and wear behaviors of peroxide cured hydrogenated nitrile rubber (HNBR) with 10 and 30 parts per hundred rubber (phr) multiwall carbon nanotube (MWCNT) and silica, respectively, were investigated. Mechanical properties (hardness, tensile modulus, ultimate tensile strength and strain, tear strength) of the rubbers were determined. Dynamic-mechanical thermal analysis was also performed and the apparent crosslink density estimated. Tribological properties were investigated in pin (steel)-on-plate (rubber), with roller (steel)-on-plate (rubber), with oscillating steel cylinder on rubber plate (Fretting) and with rolling ball (steel)-on-plate (rubber) (RBOP) test configurations. Coefficient of friction and specific wear rate (Ws) of the HNBR systems were determined. It was established that the resistance to wear increases with increasing filler content, and the incorporation of MWCNT was more advantageous than silica from the viewpoint of dry sliding and rolling performance. The friction and wear characteristics strongly depended on the test configurations. The worn surface of the HNBR systems was inspected in scanning electron microscope to conclude the typical wear mechanisms which were discussed accordingly. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Unlubricated rolling and sliding wear against steel of carbon‐black‐reinforced and in situ cured polyurethane containing ethylene/propylene/diene rubber compounds

The dry rolling and sliding friction and wear of ethylene/propylene/diene rubber containing carbon black and in situ cured polyurethane (EPDM+PUR_CB) were studied. For rolling and sliding tests against steel counterparts, different experimental conditions and tribotests were selected. The apparent network properties and phase structures of the rubbers were derived from dynamic mechanical thermal analysis and atomic force microscopy results. It was concluded that in EPDM+PUR_CB, both rubber phases, present in a 1 : 1 ratio, were continuous (interpenetrating network). The coefficient of friction (COF), specific wear rate (W_s), and heat development during the tribotests were determined. The carbon black and polyurethane contents did not much influence the COF in rolling wear tests. W_s of the ethylene/propylene/diene rubber containing carbon black went through a minimum as a function of the carbon black content. W_s of the EPDM+PUR_CB compounds decreased monotonously with an increasing amount of carbon black. The incorporation of polyurethane into the ethylene/propylene/diene rubber compounds decreased the resistance to rolling wear markedly. With carbon black filling of the ethylene/propylene/diene rubber–polyurethane compound, the COF and W_s increased and dramatically decreased, respectively, under sliding wear. The wear mechanisms were inspected with scanning electron microscopy and discussed as a function of recipe modifications and changes in the testing conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A study on the characteristics of a rubber blend of fluorocarbon rubber and hydrogenated nitrile rubber

In this study, the physical and chemical characteristics of a rubber blend of fluorocarbon rubber (FKM) and hydrogenated Nitrile Butadiene rubber (HNBR) were investigated based on the blend ratio for the purpose improving thermal resistance of HNBR and the low-temperature resistance of FKM. The blended FKM and HNBR materials showed better heat resistance, oil resistance, and fuel resistance than those of the 100 phr HNBR materials. Blended materials with added compatibilizer (KBM503) showed improved basic physical properties than those of the materials without the agent. This result agreed with a scanning electron microscopy image. The thermal properties of the blended materials based on the FKM and HNBR blend ratio were studied by Thermo Gravimetric Analysis (TGA) and differential scanning calorimetry (DSC). The TGA results showed improved heat resistance characteristics for the blended materials than those of the HNBR materials. The DSC results also showed improved characteristics of low temperature resistance with increasing HNBR contents.     

Mechanical properties,flame retardancy,hot‐air ageing,and hot‐oil ageing resistance of ethylene‐vinyl acetate rubber/hydrogenated nitrile‐butadiene rubber/magnesium hydroxide composites

The mechanical properties, flame retardancy, hot‐air ageing, and hot‐oil ageing resistance of ethylene‐vinyl acetate rubber (EVM)/hydrogenated nitrile‐butadiene rubber (HNBR)/magnesium hydroxide (MH) composites were studied. With increasing HNBR fraction, elongation at break and tear strength of the EVM/HNBR/MH composites increased, whereas the limited oxygen index and Shore A hardness decreased slightly. Hot‐air ageing resistance and hot‐oil ageing resistance of the composites became better with increasing HNBR fraction. Thermal gravimetric analysis results demonstrated that the presence of MH and low HNBR fraction could improve the thermal stability of the composites. Differential scanning calorimeter revealed that the glass transition temperature (T_g) of the composites shifted toward low temperatures with increasing HNBR fraction, which was also confirmed by dynamic mechanical thermal analysis. Atomic force microscope images showed MH has a small particle size and good dispersion in the composites with high HNBR fraction. The flame retardancy, extremely good hot‐oil ageing, and hot‐air ageing resistance combined with good mechanical properties performance in a wide temperature range (?30°C to 150°C) make the EVM/HNBR/MH composites ideal for cables application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

硅藻土/nano-MoS2复合改性氟橡胶的摩擦磨损性能研究

采用红外光谱仪、无转子硫化仪、环-块摩擦试验机、电子和光学显微镜等测试分析手段,重点考察了改性硅藻土及其与纳米二硫化钼(nano-MoS2)复合对氟橡胶(FKM)复合材料摩擦磨损性能的影响。结果表明,随着改性硅藻土含量的增加,FKM硫化胶的摩擦系数和磨损体积均呈现出逐渐降低的趋势;当改性硅藻土含量达到45 phr时,硫化胶表现出较好的摩擦磨损性能。在此基础上,再添加1 phr的nano-MoS2时,硫化胶具有最低的摩擦系数和体积磨损量,分别为0.4和1.42 mm^3,降低了16.7%和63.6%。SEM分析表明,改性硅藻土的加入有效抑制了氟橡胶的黏着磨损,适量硅藻土和nano-MoS2复合改性氟橡胶表现出轻微的磨粒磨损特征,磨损表面光滑平整,转移膜完整均匀。     

Aminofunctionalization effect on the microtribological behavior of carbon nanotube/bismaleimide nanocomposites

Original multiwalled carbon nanotubes (O‐MWCNTs) and aminofunctionalized ethylenediamine‐treated multiwalled carbon nanotubes (MWCNTs‐EDA) were mixed with bismaleimide (BMI) resin to prepare O‐MWCNT/BMI and MWCNT‐EDA/BMI composites, respectively. Raman spectroscopy, thermogravimetric analysis, and infrared spectroscopy were used to investigate the influence of aminofunctionalization on the multiwalled carbon nanotube (MWCNT) framework. Dynamic mechanical analysis, scanning electron microscopy images of the fractured surface, and field emission scanning electron microscopy of the worn surface were used to determine the possible friction and wear mechanisms of the system. The MWCNT‐EDA/BMI composite exhibited a higher friction coefficient value and a lower wear loss rate value than the O‐MWCNT/BMI composite, which was attributed to the larger number of defects caused by the aminofunctionalization of the MWCNTs, the stronger interfacial adhesion formed between the MWCNTs‐EDA and the BMI resin, and the better dispersive state of the MWCNTs‐EDA in the BMI matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Nanocomposite Formation in Hydrogenated Nitrile Rubber (HNBR)/Organo‐Montmorillonite as a Function of the Intercalant Type

Summary: Hydrogenated acrylonitrile butadiene rubber (HNBR) was melt compounded with montmorillonite (MMT) and organophilic modified MMTs prior to sulfur curing. In contrast to the micro‐composite formation resulting from the compounding of the HNBR and pristine MMT, the modified MMTs (i.e., octadecylamine: MMT‐ODA, octadecyltrimethylamine: MMT‐ODTMA, methyltallow‐bis(2‐hydroxyethyl) quaternary ammonium: MMT‐MTH intercalants) produced nanocomposites. It was found that the organoclay with primary amine intercalant (cf. MMT‐ODA) gave confined structures along with the exfoliated/intercalated structures. This was traced to its reactivity with the curatives. By contrast, the organoclays containing less reactive quaternary ammonium compounds (cf. MMT‐ODTMA, MMT‐MTH) were exfoliated and intercalated based on X‐ray diffraction (XRD) and transmission electron microscopy (TEM) results. The hydroxyl functional groups of the MMT‐MTH supported the clay dispersion. The better adhesion between MMT‐MTH and HNBR was explained by hydrogen bonding between the hydroxyl groups of the intercalant and the acrylonitrile group of the HNBR matrix. This HNBR/MMT‐MTH nanocomposite showed the best mechanical properties as verified by tensile mechanical tests and dynamic mechanical thermal analysis (DMTA). The high tensile strength along with the high elongation at break for the rubber nanocomposites were attributed to the ability of the ‘clay network’ to dissipate the input energy upon uniaxial loading.

Scheme of failure development in rubber/organoclay mixes with poor (a) and good (b) dispersion of the clay layers.     

Influences of (3-aminopropyl)triethoxysilane on the tribological behaviors of basalt fiber/acrylonitrile-butadiene rubber composites under dry friction and water-lubricated conditions

The weak interaction between the basalt fiber (BF) and acrylonitrile-butadiene rubber (NBR) weakens the BFs' effects on improving the tribological performances of the NBR composites. To solve this problem, (3-aminopropyl)triethoxysilane (APTES) was introduced via mixing into the matrix or grafting on the BF surface, respectively. The characteristics, mechanical, and tribological properties of the composites were evaluated, and the effects of the APTES and its introduction methods on the tribological properties were the main focus. The APTES mixed in the rubber matrix decreased the friction coefficient (COF) of the NBR-based composites under both dry friction and water-lubricated conditions. Especially, the APTES hydrolysis under water-lubricated condition was conducive to the formation of the water film and thus dramatically decreased the COF. The COF of the BF0-A3 and the BF12-A3 were 51% and 30% lower than that of the BF0-A0 and the BF12-A0 under water lubrication, respectively. The APTES grafted on the BF surface increased the wear resistance of the BF/NBR composites attributed to the improvement of the interaction between the BFs and the NBR matrix. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48558.     

Nonlinear viscoelasticity and stress‐softening behavior of chloroprene rubber reinforced by multiwalled carbon nanotubes

The viscoelasticity and stress‐softening behavior of chloroprene rubber (CR) filled with multiwalled carbon nanotubes (MWCNT) and carboxylated multiwalled carbon nanotubes (MWCNT‐COOH) were studied using a Rubber Process Analyzer 2000 (RPA2000). In the strain sweep measurements, it is found that CR/MWCNT and CR/MWCNT‐COOH compounds have different behavior on storage modulus (G′). With increasing strain, G′ of CR/MWCNT (100/8) compound decreases at strain less than 2°, while G′ of CR/MWCNT‐COOH (100/8) compound stays at constant, indicating that MWCNT‐COOH has stronger filler–filler network and filler–rubber interactions as compared to MWCNT in CR matrix. CR/MWCNT (MWCNT‐COOH) vulcanizates have higher G′ but lower loss modulus (G″) than the corresponding uncured compounds. Repeated strain sweep scans were carried out to study the stress‐softening behavior of CR compounds. A stress‐softening effect of the filled CR compounds is observed and becomes more pronounced with increasing loading of MWCNT or MWCNT‐COOH. The correlation between the Payne effect and stress‐softening effect of CR/MWCNT (MWCNT‐COOH) vulcanizates is also studied. It is found that the difference of the storage moduli at 0.1° and 10° strain amplitudes and the difference of storage moduli of first and second strain sweeps at 0.1° strain amplitude show a positive linear correlation. POLYM. COMPOS., 35:2194–2202, 2014. © 2014 Society of Plastics Engineers     

HNBR/EPDM blends: Covulcanization and compatibility

The covulcanization characteristics, mechanical properties, compatibility, and hot‐air aging resistance of hydrogenated nitrile‐butadiene rubber (HNBR)/ethylene‐propylene‐diene rubber (EPDM) blends cured with either sulfur or dicumyl peroxide (DCP) were studied. The difference between M_H and M_L (M_H ? M_L), rheometer graphs, selective swelling and a dynamic mechanical analysis of HNBR/EPDM blends confirmed that the peroxide curing system gives better covulcanization characteristics than the sulfur curing system and peroxide exhibited higher crosslink efficiency on EPDM while sulfur showed larger crosslink efficiency on HNBR. Dynamic mechanical analysis and morphology indicated that the compatibility between HNBR and EPDM is limited. Tensile strength and elongation at break of the sulfur‐cured blends are greater than those obtained with peroxide and increase with the HNBR fraction. The blends crosslinked with peroxide retain their tensile strength but not their elongation at break after hot air ageing better than blends vulcanized by sulfur. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Composition and property changes of HNBR and FKM elastomers after sour gas aging

Assessments of the suitability of elastomeric sealing materials for sour gas service tend to focus on physical property modifications. The lack of emphasis on understanding the chemical changes occurring during these exposure regimes seems surprising given that 40% of untapped gas reserves hold H₂S. Study of fluoroelastomer (FKM) and hydrogenated nitrile butadiene rubber (HNBR) compounds post sour gas aging revealed a number of degradative mechanisms had occurred; including, additional crosslinking, chain scission, filler modification, dehydrofluorination, low-level oxidative aging and extraction of soluble matter. In many instances, these mechanisms had opposing effects on the properties of HNBR and FKM compounds. Testing of further samples at incremental stages during aging will allow chemical changes to be correlated with property modifications as a function of time, and may provide a route to more robust lifetime predictions. Analysis of used or failed service parts would help verify that the aging regimes adopted are accelerating the relevant modes of degradation.     

Study on wear,cutting and chipping behaviors of hydrogenated nitrile butadiene rubber reinforced by carbon black and in‐situ prepared zinc dimethacrylate

In this study, the wear (Akron and DIN) and the cutting and chipping (C&C) behaviors of hydrogenated nitrile butadiene rubber (HNBR) reinforced by carbon black (N115) and in‐situ prepared zinc dimethacrylate (ZDMA) were investigated. It was validated that ZDMA was more effective than N115 to enhance the wear and C&C resistance of HNBR composites. The Akron wear resistance of the HNBR/N115 composites increased with the content of ZDMA, and the Schallamach ridges observed on the abraded surfaces became less and less clear. With increasing content of ZDMA, the failure mode of the DIN abraded surface underwent the transition from craters to Schallamach ridges, and finally to scratches. The HNBR/N115 composite reinforced by 10 phr ZDMA had the best DIN wear resistance when Schallamach ridges were the dominant failure mode. The use of 30 phr ZDMA can dramatically enhance the C&C resistance of the HNBR/N115 composites. The C&C resistance was suggested to be related to both the variation of the morphology of the C&C ridges and the direction of crack propagation as a function of the content of ZDMA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of waste ground fluororubber vulcanizate powders on the properties of silicone rubber/fluororubber blends

We prepared fluororubber (FKM) vulcanizate powder (FVP) via cryogenic grinding of the FKM commonly used in automobiles and assessed the particle size distribution of the resulting powder. We also prepared silicone rubber (SR)/FKM blends at a ratio of 25/75. Varying amounts of FKM were replaced with equal amounts of FVP within the range of 5–40 wt%, and the physical properties of the resulting SR/FKM/FVP blends were investigated and compared. The TGA curves of the SR/FKM/FVP blends obtained during the thermal property investigations indicated that pyrolysis of SR occurred within two temperature ranges, and that the SR/FKM/FVP blends with 5 wt% FVP demonstrated the highest thermal stability. The storage modulus (E') and loss modulus (E″) of the SR/ FKM/FVP blends increased as the FVP content increased. In the SR/FKM/FVP blends with 5 and 10 wt% FVP, very typical elastic‐deformation behavior was observed. On the contrary, in 40 wt% FVP, the rubber properties disappeared. The mean particle size of FVP was 41.75 μm, and particle size distribution measurements of the SR/FKM/FVP blends suggest particle coexistence such that FVP was condensed and separated. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Tribological investigations of carbon nanotube‐reinforced polymer (UHMWPE) nanocomposites using Taguchi methodology

Taguchi design techniques have been applied to investigate the significant influence of various operating and design parameters, such as contact load, rotational sliding speed, and carbon nanotubes (CNTs) concentration on the tribological properties of ultra‐high molecular weight polyethylene nanocomposites. Analysis of variance was conducted to discuss the significance of each of the parameters. Simple regression models were developed for wear rate as well as for the coefficient of friction (COF) of the nanocomposite. Applied normal force was found to be the dominant factor controlling the wear rate and friction coefficient. The significance of CNTs concentration on both COF and wear rate closely follow that of applied load. Rotational sliding speed has the least influence on the tribological properties of the nanocomposite. The developed model for predicting wear rate and the COF was found to give very good predictions against the experimental data. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44018.     

Structure,morphology, and properties of HNBR filled with N550, SiO2, ZDMA,and two of three kinds of fillers

The vulcanization properties, mechanical properties of hydrogenated nitrile rubber (HNBR) filled with carbon black (N550), zinc dimethacrylate (ZDMA), SiO₂ independently and two of three kinds of fillers together were investigated, respectively. The filler‐dispersion was characterized by the transmission electron microscopy (TEM) and dynamic mechanical properties. The results showed that HNBR composite filled with SiO₂ or ZDMA displayed high tensile strength, elongation at break and compression set. The HNBR composite filled with N550 displayed low compression set, tensile strength and elongation at break. The dispersion of SiO₂ in HNBR compound was better than that in HNBR vulcanizates because of SiO₂ particles self‐aggregation in vulcanizing processing. ZDMA particles with micron rod‐like and silky shape in HNBR compounds changed into near‐spherical poly‐ZDMA particles with nano size in HNBR vulcanizates by in situ polymerization reaction. The N550 particles morphology exhibited no much change between HNBR compounds and vulcanizates. N550/ZDMA have the most effective reinforcement to HNBR and the appropriate amount of ZDMA is about 25% of total filler amount by weights. The theory prediction for Payne effect (dispersion of the filler) shown by the dynamic properties is identical with actual state observed by TEM. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Dynamics of migration and phase selective localization of nanoclay in HNBR/ENR blends

The phase specific selective localization and dynamics of migration of nanoclay in hydrogenated acrylonitrile butadiene rubber (HNBR)/epoxidized natural rubber (ENR) blend systems is investigated. The phase specific dispersion of clay particles is monitored through measuring the online measured electrical conductance (OMEC) during mixing by means of a sensor system installed inside the chamber of an internal mixer. The results of different characterization techniques, such as atomic force microscopy, transmission electron microscopy, and small angle X‐ray scattering have been used to understand and interpret the OMEC behaviors of nanoclay‐filled rubber compounds individually (HNBR and ENR) and their blend systems. The observed online conductance is ionic in nature that arises due to the release of surfactant molecules from the clay galleries. It is observed that the OMEC behavior depends mainly on two factors: the localization of nanoclay in specific phase of the blend system and on the gradual development of blend morphology. The OMEC behavior and the supported data from the microscopic methods, clearly reveal the migration of organoclay from the ENR to HNBR phase during the mixing process, particularly localizing near the interface of the blend. Further, the localization of organoclay is also evaluated by applying the surface tension measurements based model, which also predicts the favorable localization of organoclay in HNBR phase of the blend. The work clearly suggests the OMEC method to be a powerful online tool to monitor and control the nanoclay dispersion and localization in rubber based nanocomposites during the melt mixing process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44074.     

Transport and electrical properties of natural rubber/nitrile rubber blend composites reinforced with multiwalled carbon nanotube and modified nano zinc oxide

As a surface modified zinc oxide, stearic acid‐coated nano zinc oxide (ZOS) has been prepared by sol‐gel method and was used along with N‐benzylimine aminothioformamide‐N‐cyclohexyl benzthiazyl sulfonamide binary accelerator system, multiwalled carbon nanotube (MWCNT) and sulfur for vulcanizing 20/80 natural rubber/nitrile rubber (NR/NBR) blend. Different formulations have been prepared by using 1–7 phr of MWCNT. Solvent transport and electrical properties of the rubber compounds have been investigated. The equilibrium solvent uptake (Q_∞) decreased with increase in concentration of the filler due to the decrease in the free volume and the increase in tortuousity. The conductivities of the vulcanizates increased with increase in the dosage of MWCNT from 1 phr in NBCNT₁ to 7 phr in NBCNT₄ indicating the formation of percolating network of MWCNTs in the NBR/NR matrix. POLYM. COMPOS., 35:956–963, 2014. © 2013 Society of Plastics Engineers     

Improvement in Low Temperature Izod Impact Strength of SAN/ASA/HNBR Ternary Blends Considering Competing Effects of Glass Transition Temperature and Compatibility

The competing effects of glass transition temperature (T_g) and compatibility on the low temperature Izod impact toughness of styrene–acrylonitrile copolymer/acrylonitrile–styrene‐acrylate terpolymer (SAN/ASA, 75/25, w/w) blends were investigated by using a series of hydrogenated nitrile butadiene rubbers (HNBRs) with different acrylonitrile (AN) contents. The results showed that the HNBR with AN mass content ranging from 21% to 43% had good compatibility with polymer matrix and exhibited dramatic toughening effect at 25°C. Owing to their low T_gs, only the HNBRs (AN = 21% and 25%) remained favorable toughening effect at 0 and ?30°C, respectively. Furthermore, the HNBR with 0% AN content was represented by butadiene rubber (BR). Although, BR has an extremely low T_g (?94.5°C), it is incompatible with polymer matrix, and then could not toughen the material at three temperatures (?30, 0, and 25°C, respectively). Various characterizations including solubility parameters, scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA), Fourier transform infrared (FTIR) spectroscopy, and so on were carried out to elucidate the toughening mechanism. J. VINYL ADDIT. TECHNOL., 25:225–235, 2019. © 2018 Society of Plastics Engineers     

汽车油封橡胶材料的研究进展

橡胶密封制品是汽车用橡胶制品不可缺少的重要组成部分,对汽车行驶的舒适性、安全性起到重要的作用。介绍了几种主要的汽车油封橡胶材料与性能以及研究进展,包括丁腈橡胶(NBR)、丙烯酸酯橡胶(ACM)、氟橡胶(FKM)、氢化丁腈橡胶(HNBR)、氟硅橡胶(MFQ)和聚四氟乙烯(PTFE)。     

Optimized process for the inclusion of carbon nanotubes in elastomers with improved thermal and mechanical properties

The effects of addition of reinforcing carbon nanotubes (CNTs) into hydrogenated nitrile–butadiene rubber (HNBR) matrix on the mechanical, dynamic viscoelastic, and permeability properties were studied in this investigation. Different techniques of incorporating nanotubes in HNBR were investigated in this research. The techniques considered were more suitable for industrial preparation of rubber composites. The nanotubes were modified with different surfactants and dispersion agents to improve the compatibility and adhesion of nanotubes on the HNBR matrix. The effects of the surface modification of the nanotubes on various properties were examined in detail. The amount of CNTs was varied from 2.5 to 10 phr in different formulations prepared to identify the optimum CNT levels. A detailed analysis was made to investigate the morphological structure and mechanical behavior at room temperature. The viscoelastic behavior of the nanotube filler elastomer was studied by dynamic mechanical thermal analysis (DMTA). Morphological analysis indicated a very good dispersion of the CNTs for a low nanotube loading of 3.5 phr. A significant improvement in the mechanical properties was observed with the addition of nanotubes. DMTA studies revealed an increase in the storage modulus and a reduction in the glass‐transition temperature after the incorporation of the nanotubes. Further, the HNBR/CNT nanocomposites were subjected to permeability studies. The studies showed a significant reduction in the permeability of nitrogen gas. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011