Study on the friction properties of nanocopper oxide/fluorosilicone rubber

In order to study the effect of nanocopper oxide (n-CuO) on the friction properties of fluorosilicone rubber (FVMQ), the mechanical blending method was used by adding n-CuO in preparation of FVMQ. Characterization of scanning electron microscopy, X-ray diffraction analysis, energy dispersive spectroscopy, and so on were utilized for studying the mechanism of n-CuO in FVMQ. The experimental test on tensile, tear, and friction performance were performed on n-CuO/FVMQ at both room temperature (RT) and 200°C. In comparison with n-CuO /FVMQ, the wear depth of FVMQ increased by 52.933 and 5.605 μm for RT and 200°C, respectively. Besides, the wear loss of FVMQ increased by 2.9 and 5.3 mg, respectively. The results show that for both at RT or 200°C, the addition of n-CuO changes the friction mechanism of FVMQ. The friction coefficient and wear loss of FVMQ are effectively reduced, so that the friction property of rubber matrix is significantly enhanced. In addition, the tearing property of FVMQ is improved by adding n-CuO to change the crosslinking density of FVMQ.     

Effect of adding different silane coupling agents on metal friction and wear in mixing process

The function of silane coupling agent in rubber mixing field is to combine inorganic matrix with rubber organic matrix. Silica is commonly used in the rubber mixing field to strengthen rubber. The size and amount of silica aggregates in the mixing process are important factors affecting the wear of the mixing chamber. The wear of the mixing chamber would lead to a increasing gap between the mixer chamber and the rotor, which caused the mixing efficiency reducing. It also affected the dispersion effect, then affected the mechanical and physical properties of the vulcanized rubber. In this paper, the effects of rubber compound on metal friction and wear were studied by using four silane coupling agents commonly used in rubber mixing field. The experiment was carried out at 15°C, and the attention should be paid to drying during sample preparation to avoid the deviation of the experiment caused by hydrolysis of silane coupling agent. The results showed that silanization reaction occured between silica and silane coupling agent in the mixing process. The mixing temperature was usually maintained at 145 to 155°C for 1 min in the mixer, and the silanization reaction rate was the fastest during this time. We took this rubber compound as the research object and studied the friction and wear of the rubber compound on the mixing chamber in the mixing process. The products of the silylation reaction are alcohol and water. This paper studies the corrosion and abrasion of the mixing chamber by water at high temperatures. In the mixing process, abrasive wear was the main wear form, but the corrosion wear caused by high temperature steam still occupied a large proportion.     

Frictional characteristics and vibration behavior of silicone rubber powders modified resin-based friction materials

Resin-based friction materials (RFM) are widely used in vehicle brakes. However, the thermosetting resins and rigid fillers in RFM have low toughness and produce strong vibration behavior during continuous friction processes, which adversely affects the equipment. This work proposed a method for co-blending modification of RFM with silicone rubber powders (SRP) to mitigate friction-induced vibrations, and the mechanism of silicone rubber modification on the vibrational behavior of RFM during friction was investigated. The results demonstrate that SRP-modified RFM exhibit excellent damping property and frictional characteristics. SRP modification improves the stability of the coefficient of friction and reduces fatigue wear. The wear rate of RFM modified with 10 wt% SRP reduced by 29% and the average amplitude of friction-induced vibration decreased by 35.5% compared to unmodified RFM. This work provides both theoretical and practical foundations for designing and developing RFM with high damping, low wear, and low vibration characteristic.     

Effects of ultraviolet aging on the surface properties and tribological performance of polyformaldehyde

Ultraviolet aging restricts the outdoor application of polyformaldehyde as the friction material. In this work, ultraviolet aging processes were applied to polyformaldehyde specimens and effects of the processes on their surface properties and tribological performance were evaluated. Surface morphology results show that a thin layer of white powder and micro‐cracks with further ramifications in other directions were observed on the surfaces after 400 h of ultraviolet exposure, while it is not detectable for the unaged specimens. Analysis of aging surface indicates that ultraviolet leads to the increase of micro‐cracks and the degree of crystallinity. All the tribological test results demonstrate that with the extension of ultraviolet aging time, (i) the process of damage on polyformaldehyde surface induced by ultraviolet aging is first slowly and faster afterward; (ii) the fluctuation of the friction coefficients of polyformaldehyde/GCr15 rubbing pairs increases; and (iii) the wear rate of polyformaldehyde markedly increase after aging test 400 h. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44684.     

Poly(ether ether ketone)/wrapped graphite nanosheets with poly(ether sulfone) composites: Preparation,mechanical properties,and tribological behavior

Antiwear composites with extraordinary tribological performances and good mechanical/thermal properties were developed by the dispersion of poly(ether sulfone) (PES) wrapped graphite nanosheets (GNSs) inside a poly(ether ether ketone) (PEEK) matrix via melt blending. The tribological behaviors and the mechanical/thermal properties of the composites were carefully investigated. Compared with pure PEEK and PEEK/GNS composites, the PEEK/wrapped GNS composites exhibited considerable enhancements in those performances; these were attributed to the eliminated layer of PES; this elimination not only eliminated the GNS aggregation inside the PEEK matrix for homogeneous distribution inside the PEEK matrix but also enhanced the interfacial adhesion between the PEEK and wrapped GNSs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41728.     

Effect of SiO2 nanoparticles-decorated SCF on mechanical and tribological properties of cenosphere/SCF/PEEK composites

A silicon oxide (SiO₂) nanoparticles-decorated short carbon fiber (SCF) hybrid (SCF-SiO₂) was designed to improve the weak interfacial bonding between fibers and matrix. Nano-SiO₂ was grafted onto carbon fibers by introducing amino group and epoxy group on the surface of carbon fibers and SiO₂, respectively. The chemical composition of SCF-SiO₂ was analyzed by Fourier transform infrared spectrometer and energy-dispersive spectrometry, the microstructure of SCF-SiO₂ were investigated by scanning electron microscope, and then the hybrid filler was introduced into Poly(ether ether ketone) (PEEK). Due to the strong interfacial interaction between filler and matrix, the mechanical and tribological properties of SCF-SiO₂/PEEK composites were significantly better than SCF/PEEK composites. In order to further improve the tribological properties of the composites, micrometer-sized cenosphere (CS) particles were introduced into the aforementioned system to prepare multicomponent composites. The test results of friction and wear indicate that the CS/SCF-SiO₂/PEEK composites have the optimal tribological properties. Compared with pure PEEK, the friction coefficient of CS/SCF-SiO₂/PEEK composites under 200 N load decreases by 56.4% and the specific wear rate decreases by 87.4%. Meanwhile, the thermal decomposition temperature of CS/SCF-SiO₂/PEEK composites is increased by 40 °C compared to pure PEEK. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48749.     

不同速度下丁腈橡胶摩擦特性

采用栓-盘式摩擦磨耗试验机考察了滑动速度对丁腈橡胶摩擦特性的影响,分析了其作用机理。结果表明,丁腈橡胶的摩擦系数随滑动速度的增加而降低;磨耗在较低滑动速度下,随滑动速度的增加急剧降低;在较高滑动速度下,磨耗与滑动速度几乎无关;摩擦热对丁腈橡胶的摩擦磨耗规律具有直接的影响。     

Tribological behaviors of polytetrafluoroethylene composites under dry sliding and seawater lubrication

The composites of polytetrafluoroethylene (PTFE) filled with expanded graphite (EG), poly(p‐oxybenzoyl) (POB), and basalt fiber (BF) were prepared by heating compression and sintering molding. The tribological behavior of PTFE composites was investigated with a pin‐on‐disk tester under dry conditions and seawater lubrication. The worn surface of PTFE composites and the transfer film on the counterface were observed with a scanning electron microscope. The results indicated that the incorporation of EG and POB improved the hardness of PTFE composites, and addition of BF led to greater load‐carrying capacity. Compared to pure PTFE, the coefficients of friction of PTFE composites slightly increased, but the wear rates were significantly reduced (the wear rate of composite with 3% EG being only 10.38% of pure PTFE). In addition, all the composites exhibited a lower coefficient of friction (decreases of about 0.03–0.07) but more serious wear under seawater lubrication than under dry sliding. The wear mechanism changed from serious abrasive wear of pure PTFE to slight adhesion wear of PTFE composites under both conditions. A transfer film was obviously found on the counterface in seawater, but it was not observed under dry conditions. Among all the materials tested, the PTFE‐based composite containing 20% POB (mass fraction), 2% EG, and 3% BF exhibited the best comprehensive performance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2523–2531, 2013     

Effect of titanium dioxide on the UV‐C ageing behavior of silicone rubber

The ultraviolet (UV)‐C ageing behavior of silicone rubber (SiR) incorporated with titanium dioxide nanoparticles (nano‐TiO₂) was studied under UV‐C radiation. The SiR incorporated with nano‐TiO₂ displayed excellent physical properties when exposed to UV‐C radiation. With the increase of the ageing time, the SiR with nano‐TiO₂ showed no significant change in crosslinking density and Shore A hardness. Moreover, compared with the SiR without nano‐TiO₂, the SiR incorporated with nano‐TiO₂ also exhibited high retention ratio in tensile properties, especially elongation at break. It was found that nano‐TiO₂ was a good ultraviolet light stabilizer during the UV ageing process of SiR and the optimum content of nano‐TiO₂ was 2 phr. The results of Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy showed the appearance of O? H and C?O and the decrease of the intensity of SiC₂O₂ in SiR samples during the process of UV‐C ageing. Based on these results, a possible UV ageing mechanism of SiR could be proposed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46099.     

Effect of modified Mg2B2O5w on mechanical and friction properties of oil-containing monomer casting nylon

The Mg₂B₂O₅w modified by toluene-2, 4-diisocyanate (TDI) and fatty amine (n-dodecylamine(D) or n-octadecylamine (O)) was used in oil-containing monomer casting (OMC) nylon, and the effect of modified Mg₂B₂O₅w on mechanical and friction properties of OMC nylon composites was investigated. The significant improvement of the mechanical and friction properties of composites was observed. The addition of 0.15 wt% TDI-D-Mg₂B₂O₅w or TDI-O-Mg₂B₂O₅w resulted in 21 and 20% growth in the tensile strength, 53 and 52% increase in the flexural strength, respectively. Additionally, nearly 60 and 58% reduction in the friction coefficient, about 84 and 80% decrease in the abrasion quantity. Furthermore, the worn surface of composites exhibited smooth, which confirmed the antiwear effect of Mg₂B₂O₅w. The improvement was attributed to the interfacial adhesion between whiskers and matrix by hydrogen bonds. This work provided a facile approach to the design of wear-resistant polymer composites that hold significant potential in construction machinery industry. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48856.     

Radiation–chemical modification of PTFE in the presence of graphite

PTFE with a 15% addition of graphite was subjected to irradiation using an electron beam of 10 MeV energy with absorbed doses of 26, 52, 78, 104, and 156 kGy. The effect of electron‐beam irradiation on the mechanical, sclerometic, and tribological properties, the crystallinity degree, and the morphology of the polymer surface was examined. It was found that the modification through irradiation entailed a gradual increase in the degree of crystallinity, which had a direct influence on the mechanical properties. An increase in the hardness, Young's modulus, and compressive strength of the polymer irradiated with an electron beam was also demonstrated. The electron‐beam irradiation reduced the value of components of the work‐of‐indentation, showing the growing resistance to deformation. An analysis of the scratch test parameters showed a reduced depth of penetration of the indenter into the material, proportionally to the irradiation value, at relatively constant values of the scratch depth after scratching load removal. A stereometric analysis of the scratch traces on the material allowed to determine coefficients of the wear micromechanism, β, and resistance to wear, W_β. It was found that after irradiation (especially with a dose of 4 × 26 kGy), a significant quantity of the material showed traces of ploughing, which meant a positive effect on the wear mechanism. The value of the wear resistance coefficient W_β for PTFE subjected to the absorbed irradiation dose increased intensively, which portended a significant reduction of the tribological wear compared to the nonirradiated material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42348.     

Hydroxyapatite/ultra-high molecular weight polyethylene nanocomposites fabricated by in situ hydrothermal synthesis for wear-resistance and friction reduction

In situ filling raises a possibility to restrain the agglomeration of nanomaterials in macromolecule matrices, which usually is encountered in the nanocomposites prepared by a mechanical mixing method. In this work, the nanocomposites of ultra-high molecular weight polyethylene (UHMWPE) filled with nanosized hydroxyapatite (HAP) were fabricated by an in situ hydrothermal method. The fabricated HAP/UHMWPE nanocomposites exhibited a high dispersion degree of HAP nanoparticles (NPs) and a marked improvement in stiffness, strength, toughness, glass-transition temperature, and hydrophilicity compared with the matrix and the reference composites prepared by mechanical mixing. Furthermore, pronouncedly decreased coefficients of friction and volume wear rates were observed on the in situ fabricated HAP/UHMWPE nanocomposites under dry friction, the lubrications of water, or cell culture fluid against a steel ring. The in situ fabricating strategy suggests a way to prepare highly dispersed nanocomposites, and the resulting HAP/UHMWPE nanocomposites might indicate a significant clinical prospect.     

Prediction of rubber stability by accelerated aging test modeling

This study was devoted to the prediction of polymer material aging. The prediction of the shelf time of tire rubber is used as an example in this article. The main steps of the whole procedure are described. They are the design of the experiment, accelerated aging testing, the construction of a multiresponse mathematical model and parameter estimation, and the extrapolation of the model in real‐life settings. The main pitfalls were deduced, and techniques to overcome these pitfalls are described. Novel methods of data modeling, such as evolutionary design of experiment and successive Bayesian estimation, were used. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1275–1284, 2005     

新型无石棉有机物摩擦材料的制备及其性能研究

以热压固化方法制备了一种新型无石棉有机物（NAO）摩擦材料,研究了其力学性能和摩擦磨损性能。结果表明,NAO的冲击强度可达4.25 kJ/m2,硬度为68 HRM,力学性能优异;材料具有适中的摩擦系数,摩擦系数随温度升高而稳步升高,无热衰退现象,且高温和低温的摩擦系数曲线均较平稳;材料具有极低的磨损率;主要摩擦性能均优于国家标准所规定的技术要求。     

Bioinspired oil-soluble polymers based on catecholamine chemistry for reduced friction

Reduction of friction and wear contributes significantly to energy saving for mechanical system as considerable energy has been consumed in various forms of friction worldwide. In the present study, two kinds of dopamine-based oil-soluble polymers were synthesized by atom transfer radical polymerization (DOPA-BiBB-pLMA) and photopolymerization (DOPA-I2959-pLMA), and modified onto the Ti6Al4V sheet by the “grafting to” method. The characterizations of nuclear magnetic resonance, Fourier transform infrared spectrum, water contact angle, and X-ray photoelectron spectroscopy confirmed that the polymers were successfully grafted onto the Ti6Al4V surface. Additionally, a series of tribological tests were performed in oil environment using a universal materials tester under different experimental conditions. It was shown that the coefficient of friction using the Ti6Al4V sheets grafted by the dopamine-based polymers was reduced by 23.5–46.2% compared with bare Ti6Al4V sheet. Furthermore, the wear depth and wear volume were also greatly decreased with the introduction of the dopamine-based polymers. DOPA-I2959-pLMA showed slightly better lubrication enhancement than that of DOPA-BiBB-pLMA, which may be attributed to the relatively higher polymerization degree. In summary, a universal “grafting to” surface modification approach was proposed bioinspired by catecholamine chemistry, which remarkably reduced friction and wear of the tribopairs with the introduction of oil-soluble polymers.     

Wear and thermal behavior of basalt fiber reinforced rice husk/polyvinyl chloride composites

Plant fiber reinforced polymer composites (PFRPs) in practical application are often subjected to both complex friction and variable temperature environments. The present work explores the possibility of reinforcing rice husk/polyvinyl chloride (RH/PVC) composites with basalt fibers (BF) for developing a new wear resistant material with improved thermal stability. The results showed that the structural strength and wear resistance of the composites increased at first and then decreased with an increasing ratio of BF/RH, the highest value occurred at a BF/RH ratio of 8/42. The thermal stability of composites had a positive relationship with BF/RH ratio. The composites added with BF all possessed improved performance in comparison with unadded composites. Hence, the findings of this article proposed some new perspectives on improving the wear resistance and thermal stability of PFRPs that would broaden their practical application.     

Effect of surface modification of titanium dioxide on the UV-C aging behavior of silicone rubber

Surface modification of titanium dioxide (TiO₂) nanoparticles (NPs) by silane coupling agents and the ultraviolet-C (UV-C) aging behavior of silicone rubber (SiR) incorporated with the modified TiO₂ NPs were investigated in this work. The SiR samples incorporated with TiO₂ NPs displayed excellent stability against the UV-C radiation. In order to improve the dispersion of TiO₂ NPs in the SiR matrix, the surface of TiO₂ NPs was modified with 3-aminopropyl triethoxysilane and 3-trimethoxysilyl propyl methacrylate, respectively. The surface modification of TiO₂ NPs was characterized by thermal gravimetric analysis and Fourier transform infrared spectroscopy. The dispersion stability of the pristine TiO₂ NPs and surface silane-modified TiO₂ NPs was evaluated in an organic solvent (toluene). Effect of surface modified TiO₂ NPs on the UV-C aging behavior of SiR was evaluated in terms of the change of surface morphology, tensile properties, hardness, crosslinking density, and surface microstructure before and after the UV-C aging. The results showed that surface modification of TiO₂ NPs with silane coupling agents could improve the dispersion of TiO₂ NPs in the SiR matrix. Moreover, the SiR with modified TiO₂ NPs showed an improved aging resistance to the UV-C radiation, compared with the samples with pristine TiO₂ NPs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47170.     

Tribological performance of filled PTFE‐based friction material for ultrasonic motor under different temperature and vacuum degrees

In this work, a glass fiber reinforced polytetrafluoroethylene (PTFE)‐based friction material with good properties for ultrasonic motor was fabricated. The effects of temperature and vacuum degree on the tribological behavior of the PTFE‐based friction material were investigated; the evolutions of friction‐wear modes and mechanisms were also discussed as function of temperature and vacuum degree. The results show that the delamination and fatigue wear are predominant under the effects of repeated shearing and dynamic contact under atmospheric environment. While wear mechanisms change from adhesive to abrasive and fatigue wear as it is cooled from 30 to ?60 °C at vacuum environment. Under high vacuum, adhesive wear was prone to taking place at room temperature for high frictional heat which increased the wear rate and extended the running‐in period. Experiment shows that the highest no‐load speed, output power, and holding torque of ultrasonic motor at room temperature under atmospheric environment are 220 rpm, 9.9 W, and 1.21 N m, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45358.     

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.     

Hybrid polymer matrix composite (UHMWPE-HPMC) as solid particle erosion resistant coating for sharp pipe elbows using numerical simulation and experimental analysis

A hybrid polymer matrix composite coating, resistant to solid particle erosion inside sharp elbows, consisting interlocking chains of molecules with the ability to deflect the surface impact stress and to uniformly distribute stresses along the hard-ceramic reinforcement mixture surface was developed. Formulated mixture of ceramic reinforcement particles mixtures (alumina, tungsten carbide, and silicon carbide) with polymer coupling agents; to increase adhesion to the metal surface, led to 600–700 HVN in ternary and 500–550 HVN in binary mixtures. This behavior coincides with high shear strength of 70–76 MPa, Young's and shear modulus of 8.86 and 13.4 GPa in ternary 15%Al₂O₃-5%WC-10%SiC, respectively. The low erosion weight loss of 0.1% and small coefficient of friction near 0.18 indicates the significant wear resistance of the ternary sample. The electron microscopic micrographs determined the dense smooth coating surfaces with adhesive interfaces with the substrate.