铜及其氧化物填充UHMWPE力学、摩擦学性能研究

在超高分子量聚乙烯(UHMWPE)中分别填充铜粉、氧化铜粉和氧化亚铜粉,用万能材料试验机、摩擦磨损试验机等研究了三种填料对UHMWPE复合材料力学性能和摩擦磨损性能的影响,利用扫描电子显微镜对几种材料的磨损表面进行了观察和分析。结果表明,在填料添加量相同时,铜粉的减摩耐磨效果最好,氧化铜粉的减摩耐磨效果次之,氧化亚铜粉的减摩耐磨效果最差;以体积分数25％的铜粉填充的UHMWPE复合材料,具有良好的力学性能和摩擦学性能,是一种有应用前景的聚合物基减摩抗磨材料。     

Enhancement of mechanical and tribological properties in ring‐opening metathesis polymerization functionalized molybdenum disulfide/polydicyclopentadiene nanocomposites

This study focuses on the possibility of improving performance properties of polydicyclopentadiene (PDCPD) nanocomposites for engineering applications using nanoparticles. In this article, molybdenum disulfide/polydicyclopentadiene (MoS₂/PDCPD) nanocomposites have been prepared by in situ ring‐opening metathesis polymerization using reaction injecting molding (RIM) process. To enhance the interfacial adhesion between the fillers and PDCPD matrix, the surface modified MoS₂ nanoparticles hybridized with dialkyldithiophosphate (PyDDP) were successfully prepared by in situ surface grafting method. The effect of low MoS₂ loadings (<3 wt %) on the mechanical and tribological behaviors of PDCPD was evaluated. The results indicated that the friction coefficient of the MoS₂/PDCPD nanocomposites was obviously decreased and the wear resistance of nanocomposites was greatly improved by the addition of PyDDP‐hybridized MoS₂ nanoparticles; meanwhile, the mechanical properties were also enhanced. The MoS₂/PDCPD nanocomposites filled with 1 wt % PyDDP‐hybridized MoS₂ exhibited the best mechanical and anti‐wear properties. The friction coefficient was shown to decrease by more than 40% compared to pure PDCPD by incorporating just 1 wt % hybridized MoS₂ nanoparticles, and modest increase in modulus and strength was also observed. The reinforcing and wear‐resistant mechanisms of MoS₂/PDCPD nanocomposites were investigated and discussed by scanning electron microscopy. The well interfacial compatibility between the particle/matrix interfaces played an important role for the improved mechanical and tribological properties of MoS₂/PDCPD nanocomposites in very low MoS₂ loadings. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Tribological properties of bismaleimide composites with surface‐modified SiO2 nanoparticles

In this article, the surface of SiO₂ nanoparticles was modified by silane coupling agent N‐(2‐aminoethyl)‐γ‐aminopropylmethyl dimethoxy silane. The bismaleimide nanocomposites with surface‐modified SiO₂ nanoparticles or unmodified SiO₂ nanoparticles were prepared by the same casting method. The tribological performance of the nanocomposites was studied on an M‐200 friction and wear tester. The results indicated that the addition of SiO₂ nanoparticles could decrease the frictional coefficient and the wear rate of the composites. The nanocomposites with surface‐modified SiO₂ nanoparticles showed better wear resistance and lower frictional coefficient than that with the unmodified nanoparticles SiO₂. The specific wear rate and the steady frictional coefficient of the composite with 1.0 wt % surface‐modified SiO₂ nanoparticles are only 1.8 × 10^?6 mm³/N m and 0.21, respectively. The dispersion of surface‐modified SiO₂ nanoparticles in resin matrix was observed with transmission electron microscope, and the worn surfaces of pure resin matrix and the nanocomposites were observed with scanning electron microscope. The different tribological behavior of the resin matrix and the filled composites should be dependent on their different mechanical properties and wear mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

SiO2-covered graphene oxide nanohybrids for in situ preparation of UHMWPE/GO(SiO2) nanocomposites with superior mechanical and tribological properties

The modified Hummer technique was used in the preparation of graphene oxide (GO) nanosheets, and then SiO₂ decorated GO [GO(SiO₂)] nanosheets were synthesized via the sol–gel method. Then, ultrahigh-molecular-weight polyethylene (UHMWPE) nanocomposites loaded with 0.5, 1, 1.5, and 2 wt % of GO(SiO₂) were prepared using magnesium ethoxide/GO(SiO₂)-supported Ziegler–Natta catalysts via the in situ polymerization. Morphological study of the prepared polymer powders was assessed using field-emission scanning electron microscopy, which showed that GO(SiO₂) nanohybrids have been uniformly dispersed and distributed into the UHMWPE matrix. Also, the neat UHMWPE and its nanocomposites were evaluated with different analyses, including viscosity-average molecular weight measurement, differential scanning calorimetry, thermogravimetric analysis, tensile test, scratch hardness, and pin-on-disk test. The characterization of the UHMWPE nanocomposites indicated that many characterizations, including the mechanical, thermal, and tribological properties of UHMWPE, were significantly improved by incorporation of these new nanosheets in spite of the molecular weight reduction of the polymeric matrix and the improved flowability and processability of the produced nanocomposite. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47796.     

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.     

Production and characterization of UHMWPE/fumed silica nanocomposites

Ultrahigh‐molecular‐weight polyethylene (UHMWPE)/fumed silica nanocomposites were prepared via in situ polymerization using a bi‐supported Ziegler‐Natta catalytic system. Nanocomposites with different nanoparticle weight fractions were produced in order to investigate the effect of fumed silica on thermal and mechanical properties of UHMWPE/fumed silica nanocomposites. The viscosity average molecular weight (M ) of all samples including pure UHMWPE as the reference sample and nanocomposites were measured. Scanning electron microscope (SEM) images showed the homogenous dispersion of nanoparticles throughout the UHMWPE matrix while no nanoparticle cluster has been formed. Crystallization behavior of nanocomposites was investigated by differential scanning calorimetry (DSC), which showed a slight increase in melting temperature by enhancing the nanoparticle concentration while no significant change was observed in the crystallization temperature as the fumed silica concentration enhanced. The improvement in all thermal stability parameters was recorded by thermogravimetric analysis (TGA). Besides, via tensile testing, it was confirmed that addition of nanoparticles caused considerable improvement in such mechanical properties as Young's modulus, yield stress, and tensile strength of samples while the elongation at break declined by addition of more nanoparticles. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

In situ filling of SiO2 nanospheres into PTFE by sol–gel as a highly wear-resistant nanocomposite

In situ filling of nanomaterials into polymers facilitates the dispersion of the nanofillers and their interface combination with the matrices, and reduces the agglomeration encountered in the nanocomposites prepared by a mechanical mixing method. Polytetrafluoroethylene (PTFE) nanocomposites filled with SiO₂ nanospheres (SNS) were fabricated by an in situ sol–gel method in this paper. The SNS in situ filled was highly dispersed in PTFE and showed an excellent combination with the matrix, and the fabricated SNS/PTFE nanocomposites were found a pronounced improvement in stiffness, hardness, glass transition temperature, and hydrophobicity in comparison with the pristine PTFE and the ones prepared by mechanical mixing with the same content. Furthermore, significantly reduced coefficients of friction and volume wear rates were observed on the SNS/PTFE nanocomposites prepared by in situ sol–gel. An operating temperature high up to 200°C and very low volume wear rate were accessible on the optimized SNS/PTFE nanocomposite by in situ filling. The methodology, in situ filling of nanofillers into matrices, might pave a way to prepare nanocomposites with excellent mechanical, thermal, and tribological properties.     

Role of in situ generated silica for rubber science and technology

Filled rubbers have a long history in rubber technology. Filler morphology in the rubber matrix significantly influences the performance of filled rubber products. Therefore, we have to achieve a certain morphology of filler in the rubbery matrix in order to enjoy good reinforcement. However, it has not been sufficiently known what kind of morphology is necessary for the reinforcement, because preparations of adequate models for the characterization of filler morphology have been difficult. The in situ silica filling of the rubber matrix can be modeled for the preparations. In this paper, the characteristic features of in situ silica generated in diene rubbers are reviewed, citing recent reports. Two important models are presented. One is a homogeneous silica filling in situ, producing soft rubber nanocomposites. The other is the formation of an in situ silica filler network, creating stiff rubber nanocomposites. The controlled in situ silica filling is useful to evaluate the reinforcement effect of filler in a rubber matrix. © 2016 Society of Chemical Industry     

Mechanical and tribological properties of polyoxymethylene modified with nanoparticles and solid lubricants

Polyoxymethylene (POM) composites modified with nanoparticles, polytetrafluoroethylene (PTFE) and MoS₂ were prepared by a twin‐screw extruder. The effect of nanoparticles and solid lubricant PTFE/MoS₂ on mechanical and tribological properties of the composites were studied. Tribological tests were conducted on an Amsler friction and wear tester using a block‐on‐ring arrangement under dry sliding and oil lubricated conditions, respectively. The results showed that generally speaking POM nanocomposites had better stiffness and tribological properties than corresponding POM composites attributed to the high surface energy of nanoparticles, except that the tensile strength of three composites and dry‐sliding tribological properties of POM/3%Al₂O₃ nanocomposite decreased due to the agglomeration of nanoparticles. Tribological properties differed under dry sliding and oil lubricated conditions. The friction coefficient and wear volume of POM nanocomposites under oil lubricated condition decreased significantly. The increased deformation resistance supported the increased wear resistance of POM nanocomposites. POM/PTFE/MoS₂/3%Al₂O₃ nanocomposite had the best mechanical and tribological properties of all three composites, which was attributed to the synergistic effect of nanoparticles and PTFE/MoS₂. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

In situ emulsion polymerization and characterization of PVAc nanocomposites including colloidal silica nanoparticles for wood specimens bonding

Polyvinyl acetate (PVAc) nanocomposites for wood adhesives containing different amounts of colloidal silica nanoparticles (CSNs) were synthesized via in situ one-step emulsion polymerization. The adhesion strength of wood specimens bonded by PVAc nanocomposites was investigated by the tensile test. Thermal properties of PVAc nanocomposites were also characterized by differential scanning calorimetry and thermogravimetric analysis. Rheological and morphological properties of the PVAc nanocomposites were investigated using rheometric mechanical spectrometry and field emission scanning electron microscopy (FESEM), respectively. The obtaining results showed that the shear strength of PVAc nanocomposite including 1 wt. % CSNs has the highest shear and tensile strength about 4.7 and 3.2 MPa, respectively. A small increment of T_g (~3 °C) and considerable increment of the ash content proved the enhancement of PVAc thermal characterization in the presence of CSNs. FESEM results showed uniform dispersion of nanoparticles throughout the PVAc matrix due to using the in situ emulsion polymerization process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48570.     

Influence of fillers dispersion on friction and wear performance of solution styrene butadiene rubber composites

Development of structure–properties relationships between the fillers/rubber matrix interface chemistry and the dispersion and interfacial adhesion properties of the rubber composites is critical to predict their bulk mechanical and tribological properties. In this paper, three solution styrene butadiene rubber (SSBR) composites containing various fillers with tailored interfacial chemistry were prepared via conventional mixing technique. Subsequently, thermal and structural features of filled SSBR composites were monitored by TG, DSC, XRD, XPS, FESEM and TEM, respectively. Sliding contact experiments were conducted to study tribological properties of styrene butadiene rubber composites under dry and wet conditions. It was shown that the SSBR filled with silicon dioxide nanoparticles significantly reduced both the friction coefficient and the wear against marble block. On the contrary, it exhibited an increased friction coefficient and wear under wet friction conditions due to the specific superior wet‐skid resistance of silicon dioxide nanopartilce filled rubber composites, a good dispersion of silicon dioxide nanopartilce in the rubber matrix and strong interfacial adhesion between nanoparticles and rubber matrix. In addition, the influence of fillers dispersion and interfacial adhesion on friction and wear of styrene butadiene rubber composites was evaluated employing theoretical calculation, and the predicted results were in agreement with the experimental observations. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43589.     

Effect of polyethylene‐graft‐maleic anhydride as a compatibilizer on the mechanical and tribological behaviors of ultrahigh‐molecular‐weight polyethylene/copper composites

Ultrahigh‐molecular‐weight polyethylene/copper (UHMWPE/Cu) composites compatibilized with polyethylene‐graft‐maleic anhydride (PE‐g‐MAH) were prepared by compression molding. The effects of the compatibilizer on the mechanical, thermal, and tribological properties of the UHMWPE/Cu composites were investigated. These properties of the composites were evaluated at various compositions, and worn steel surfaces and composite surfaces were examined with scanning electron microscopy and X‐ray photoelectron spectroscopy. The incorporation of PE‐g‐MAH reduced the melting points of the composites and increased their crystallinity to some extent. Moreover, the inclusion of the PE‐g‐MAH compatibilizer greatly increased the tensile rupture strength and tensile modulus of the composites, and this improved the wear resistance of the composites. These improvements in the mechanical and tribological behavior of the ultrahigh‐molecular‐weight‐polyethylene‐matrix composites with the PE‐g‐MAH compatibilizer could be closely related to the enhanced crosslinking function of the composites in the presence of the compatibilizer. Moreover, the compatibilizer had an effect on the transfer and oxidation behavior of the filler Cu particulates, which could be critical to the application of metallic‐particulate‐filled polymer composites in engineering. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 948–955, 2004     

基于超高分子量聚乙烯及其复合材料摩擦学研究进展

综述了超高分子量聚乙烯(UHMWPE)及其改性复合材料的摩擦磨损规律的研究进展。传统方法改性对UHMWPE摩擦学性能的改善程度有限,而纳米粒子由于自身的表面效应、体积效应、量子尺寸效应和宏观量子隧道效应,使得纳米改性UHMWPE的摩擦学性能得到了很好的改善。     

Preparation and tribological properties of poly(methyl methacrylate)/styrene/MWNTs copolymer nanocomposites

Poly(methyl methacrylate)/styrene/multi‐walled carbon nanotubes (PMMA/PS/MWNTs) copolymer nanocomposites with different contents have been prepared successfully by means of in situ polymerization method. The structure and the microhardness of PMMA/PS/MWNTs copolymer nanocomposites were characterized. The tribological behaviors of the copolymer nanocomposites were investigated by a friction and wear tester under dry conditions. The relative humidity of the air was about 50% ± 10%. Comparing with pure PMMA/PS copolymer, the copolymer nanocomposites showed not only better wear resistance but also smaller friction coefficient. MWNTs could help the nanocomposites dramatically improve the wear resistance property. The mechanisms of the improvements on the tribological properties of the PMMA/PS/MWNTs copolymer nanocomposites were also discussed in detail. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Ultrahigh molecular weight polyethylene/polypropylene/organo‐montmorillonite nanocomposites: Phase morphology,rheological, and mechanical properties

Phase morphology, rheological, and mechanical properties of ultrahigh molecular weight polyethylene (UHMWPE)/PP/organo‐montmorillonite nanocomposites were investigated in this work. The results of TEM and XRD indicated that the organo‐montmorillonite PMM prepared with the complex intercalator [2‐methacryloyloxyethyldodecyldimethylammonium bromide/poly(ethylene glycol)] were exfoliated and dispersed into UHMWPE matrix, and the synergistic effect of the complex intercalator on the exfoliation and intercalation for montmorillonite occurred. Besides, the presence of PMM in UHMWPE matrix was found able to lead to a significant reduction of melt viscosity and enhancement in tensile strength and elongation at break of UHMWPE, except that izod‐notched impact strength was without much obvious change. The dispersed PMM particles exhibited a comparatively large two‐dimensional aspect ratio (L_clay/d_clay = 35.5), which played an important role in determining the enhancement of mechanical properties of UHMWPE nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Improvement of the tribological behavior of ultra‐high‐molecular‐weight polyethylene by incorporation of poly (phenyl p‐hydroxyzoate)

Ultra‐high‐molecular‐weight polyethylene/poly (phenyl p‐hydroxyzoate) composites (coded as UHMWPE/PPHZ) were prepared by compression molding. The effects of the poly (phenyl p‐hydroxyzoate) on the tribological properties of the UHMWPE/PPHZ composites were investigated, based on the evaluations of the tribological properties of the composites with various compositions and the examinations of the worn steel surfaces and composites structures by means of scanning electron microscopy and transmission electron microscopy. It was found that the incorporation of the PPHZ led to a significant decrease in the wear rate of the composites. The composites with the volume fraction of the PPHZ particulates within 45% ～ 75% showed the best wear resistance. The friction coefficient of the UHMWPE/PPHZ composites decreased with increasing load and sliding velocity, while the wear rates increased with increasing load. This was attributed to the enhanced softening and plastic deformation of the composites at elevated load or sliding velocity. The UHMWPE/PPHZ composites of different compositions had differences in the microstructures and the transfer film characteristics on the counterpart steel surface as well. This accounted for their different friction and wear behaviors. The transfer film of the UHMWPE/PPHZ composites appeared to be thinner and more coherent, which was largely responsible for their better wear resistance of t composite than the UHMWPE matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2336–2343, 2005     

Tribological behaviors of polyurethane composites containing self‐lubricating microcapsules and reinforced by short carbon fibers

Self‐lubricating microcapsules containing methyl silicone oil as core materials, were prepared with poly(melamine‐formaldehyde) as shell material by in situ polymerization method. Combining with synergistic effect of the short carbon fibers (SCFs) which were systematically treated by liquid‐phase oxidation and chemical grafting, they were simultaneously adopted as reinforcing additives to improve the tribological and mechanical properties of polyurethane materials. The tribological behaviors and mechanical properties of the polyurethane composites have been investigated by a block‐on‐ring wear tester and electronic universal testing machine, respectively. The results indicate that the friction coefficient and wear rate of polyurethane composites without SCFs significantly decreased with increased self‐lubricating microcapsule concentration from 2.5 to 10 wt % due to the release of methyl silicone oil; meanwhile, the polyurethane composites filled with 10 wt % microcapsule and 15 wt % SCFs not only exhibited the lowest friction and wear behaviors, but also improved mechanical strength and thermal stability of polyurethane composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45331.     

Role of the degree of acetalization on dynamic mechanical properties of polyvinyl butyral/carbon nanotube composites

In this work, polyvinyl butyral (PVB) nanocomposites reinforced with 0.1–1.0 wt % of pristine [carbon nanotube (CNT)] or oxidized (CNTO) multiwalled CNTs were synthesized via in situ polymerization. It was found that the presence of the reinforcement during the synthesis altered the degree of acetalization of PVB. Dynamic mechanical analyses showed that PVB nanocomposites containing 0.5 wt % of pristine CNT had the best adhesion factor, with increases of about 30% in the storage modulus. On the other hand, PVB/CNTO 1.0 wt % nanocomposites achieved the best reinforcement efficiency factor (“C” coefficient). It is concluded that the in situ polymerization improves dispersion and final properties of the nanocomposite only if the nanoparticles are able to form relevant interfacial interactions during the PVB synthesis. In addition, it was verified that the presence of CNT or CNTO altered the degree of acetalization of PVB, which strongly influences the final properties of the nanocomposites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48146.     

Influence of B4C nanoparticles on mechanical behaviour of Silicon brass nanocomposite through mechanical alloying and hot pressing

This research article has concentrated to develop a novel silicon brass of [82Cu4Si14Zn]_100-x – x wt.% B₄C (x = 0, 3, 6, 9, and 12) nanocomposites which were synthesized by mechanical alloying followed by vacuum hot pressing for consolidation of powders into bulk samples. Single vial planetary ball mill was used to synthesize the nanocomposite powders in which the ball-to-powder ratio of 10:1 with the milling time of 20 h was used. The milled powders were compacted and sintered simultaneously using vacuum hot pressing equipment for 1 h at 900 °C. The structural, mechanical and tribological properties were characterized and investigated by x-ray line profile analysis (XRD), scanning electron microscopy (SEM), electron backscattered diffraction images (EBSD), energy dispersive x-ray spectroscopy (EDS), Vickers microhardness, compression test, and dry sliding wear behaviour analysis. It has been found that B₄C nanoparticles had homogeneously distributed and embedded in the nanocrystallite matrix. As a result, the fabricated nanocomposites were exhibited superior properties than the conventional alloy. Here, 12 wt% B₄C reinforced silicon brass of bulk nanocomposite was produced higher hardness and compressive strength than the unreinforcement matrix. Further, the worn morphologies were evidenced the mild wear occurred at higher reinforced nanocomposites owing to decohesion and lower wear rate with considerable wear resistance.     

Mechanical and tribological behaviors of polyamide 66/ultra high molecular weight polyethylene blends

The blends of polyamide (PA) and ultra high molecular weight polyethylene (UHMWPE) were prepared by a Brabender DSE25 co‐twin screw extruder, and maleic anhydride (MAH) grafted high‐density polyethylene (HDPE) was used as a compatibilizer. A chemical reaction between MAH group of MAH‐g‐HDPE and terminal amino group of PA was testified by FT‐IR analysis. Mechanical and tribological tests showed that the tensile and bending strength of PA decrease with the increase of UHMWPE. Besides, the mechanical strengths of PA/UHMWPE blends were improved by adding appropriate MAH‐g‐HDPE. The chemical reaction between MAH‐g‐HDPE and PA ameliorated the homogeneous dispersing ability of UHMWPE in the blend. The friction coefficient and volume wear rate of the PA/UHMWPE blends decreased apparently with the increase of UHMWPE, as was probably that UHMWPE has straight chain structure and good flexibility; therefore, a transferring film could be easily formed on the steel surface with the increase of UHMWPE. In friction process, the wear resistance of the blends was relative to the mechanical property of the blends when the amount of the transferring layer reached to a certain value. POLYM. ENG. SCI., 47:738–744, 2007. © 2007 Society of Plastics Engineers.