Two‐body abrasive wear behavior of particulate filled polyamide66/polypropylene nanocomposites

An experimental characterization of the abrasive wear behavior of clay and clay plus short carbon fiber filled polyamide66/polypropylene (PA66/PP) nanocomposites has been investigated. Two‐body abrasive wear studies were carried out using pin‐on‐disc wear tester under multi‐pass condition against the water proof silicon carbide abrasive paper. It was observed that the clay reinforcement is detrimental to the abrasive wear resistance of PA66/PP blend. A combination of clay and short carbon fiber in PA66/PP blend improved the abrasive wear performance than those of clay filled PA66/PP nanocomposites. Further, on the basis of microscopic observation of the worn surfaces, dominant wear mechanisms were discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effects of SEBS-g-MA on the Tribological Behavior of PA66/Montmorillonite Nanocomposites

The tribological behavior of PA66, PA66/Montmorillonite nanocomposites, and PA66/(SEBS-g-MA + Montmorillonite) nanocomposites was studied by means of a ring-on-block tribometer. The morphologies of the worn surfaces of specimens were observed with scanning electron microscopy (SEM). Wear of all of the specimens increases with increasing load; meanwhile, the friction coefficient decreases. Wear of PA66/Montmorillonite is larger than that of PA66. Adding SEBS-g-MA to PA66/Montmorillonite improves the wear resistance. The friction coefficient of PA66/Montmorillonite is slightly less than that of PA66 at various loads. The friction coefficient of PA66/(SEBS-g-MA + Montmorillonite) is the lowest.     

Friction and wear behaviors of several polymers under oil-lubricated conditions

The friction and wear properties of polytetrafluoroethylene (PTFE), polyimide (PI), and polyamide 66 (PA66) sliding against GCr15 bearing steel under both dry and oil-lubricated conditions were studied by using an MHK-500 ring-block wear tester (Timken wear tester), and then Stribeck's curves of PTFE, PI, and PA66 under lubrication of the oil were given out. The worn surfaces of these polymers and the transfer films formed on the counterfaces were examined by using a scanning electron microscope (SEM) and an optical microscope, respectively. Experimental results show that the friction and wear-reducing properties of PTFE, PI, and PA66 can be greatly improved by lubrication with liquid paraffin, and the friction coefficients can be decreased by 1 order of magnitude compared to those in dry friction condition. Under lubrication of liquid paraffin, the friction coefficients of PTFE, PI, and PA66 decrease with the increase of load, but the wear increases with the increase of load. The variations of friction coefficients with load for PTFE, PI, and PA66 under lubrication of liquid paraffin can be described properly by the Stribeck's curves, as given out in this article. Under higher loads and sliding speeds in liquid paraffin lubrication, the friction and wear reducing properties of PA66 are the best, and those of PTFE are the worst; therefore, PA66 is also very suitable for applications in oil-lubricated conditions. Meanwhile, SEM and optical microscope investigations show that the wear and transfer of PTFE, PI, and PA66 can be greatly reduced by lubrication of liquid paraffin, but they still take place. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2175–2182, 1998     

表面处理对CF/PA66复合材料磨损性能的影响

采用电化学氧化法和氨气法分别对碳纤维(CF)进行表面处理后,用双螺杆挤出机共混造粒和注塑成型制备CF/PA66复合材料,研究了表面处理对CF/PA66复合材料磨损性能的影向。结果表明:随着CF含量的增加,CF/PA66复合材料的耐磨损性能提高;对CF进行表面处理,可提高CF/PA66复合材料的耐磨损性能,氨气法得到的CF/PA66复合材料的耐磨损性能优于电化学氧化法,当添加CF质量分数为15%时,其体积磨损速率比电化学氧化法的约降低48%。     

Enhanced wear performance of nylon 6/organoclay nanocomposite by blending with a thermotropic liquid crystalline polymer

A new approach for improving the wear performances of nylon 6 (PA6)/clay nanocomposites was examined in this study. Two hybrid nanocomposites were prepared by melt blending a thermotropic liquid crystalline polymer (TLCP) and a well‐dispersed PA6/clay nanocomposite, but with and without the incorporation of maleic‐anhydride grafted polypropylene (MAPP) as compatibilizer. The addition of MAPP improved the compatibility between TLCP and matrix and thus enhanced the fibrillation of dispersed TLCP phase. Wear‐testing results revealed that the wear resistance of the compatibilized hybrid nanocomposite could be improved effectively, as indicated by the low values of specific wear rate and frictional coefficient, especially under high‐normal load (i.e., 80 N). Based on the characterization on the worn damage and the debris, it was suggested that abrasive wear was the main‐damage mechanism for all the materials under investigation, except for the compatibilized hybrid nanocomposite. For this system, the wear damage was caused by a combination of abrasive and adhesive wearing because of the formation of transfer film on the counter pin surface from the wear debris. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Tribological behavior of the polyamide composite coating filled with different fillers under dry sliding

The polyamide (PA) composite coating filled with the particles of microsized MoS₂, microsized graphite, and nano‐Al₂O₃, respectively, were prepared by flame spraying. The friction and wear characteristics of the PA coating and composite coating filled with the varied content of filler under dry sliding against stainless steel were comparatively investigated using a block‐ring tester. The morphologies of the worn surfaces and transfer films on the counterpart steel ring were observed on a scanning electron microscope. The result showed that the addition of fillers to the composite coatings changed significantly the friction coefficient and wear rate of the coatings. The composite coatings filled with a low level content of fillers showed lower wear rate than did pure PA coating under dry sliding; especially the MoS₂/PA composite coating had the lowest wear rate among these composite coatings. The composite coatings with a high level content of fillers had higher wear rate than did pure PA coating, except of the Al₂O₃/PA composite coating. The bonding strengths between the polymer matrix and fillers changed with the content of the fillers, which accounted for the differences in the tribological properties of the composite coatings filled with the varied content fillers. On the other hand, the difference in the friction and wear behaviors of the composite coatings and pure coating were attributed to the difference in their worn surface morphologies and transfer film characteristics. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Nanoindentation and morphological studies on nylon 66/organoclay nanocomposites. II. Effect of strain rate

Strain rate effects on surface deformation behavior of exfoliated nylon 66 (PA66)/organoclay nanocomposites have been explored by nanoindentation in present study. Sharp indenter (Berkovich) has been used to indent on the surfaces of polymer/clay nanocomposite with different strain rates. Significant strain-rate hardening has been found consistently existing in both neat PA66 and its nanocomposite systems from surface to subsurface (a few micron deep into the bulk). However, strain rate shows almost no effect on the elastic moduli of the neat system and the nanocomposites. The elastic modulus and hardness increase with the indentation depth due to inhomogeneous distributions of the crystalline morphology as well as clay concentration for the case of the nanocomposites along the indentation direction. The mechanical properties observed are correlated with the inhomogeneous microstructures of the studied systems. The plastic index of PA66 and the nanocomposites have been evaluated as a function of strain rate.     

Mechanical and tribological properties of PA66/PPS blend. III. Reinforced with GF

Based on previous work, 70 vol % PA66/30 vol % PPS blend was selected as a matrix, and the PA66/PPS blend reinforced with different content of glass fiber (GF) was prepared in this study. The mechanical properties of PA66/PPS/GF composites were studied, and the tribological behaviors were tested on block‐on‐ring sliding wear tester. The results showed that 20–30 vol % GF greatly increases the mechanical properties of PA66/PPS blend. When GF content is 20 vol %, the friction coefficient of composite is the lowest (0.35), which is decreased by 47% in comparison with the unfilled blend. The wear volume of the GF‐reinforced PA66/PPS blend composite decreases with the increase of GF content. However, the wear‐resistance is not apparently improved by the addition of GF in the experimental range for comparison with unfilled PA66/PPS blend. The worn surface and the transfer film on the counterface were examined by scanning electron microscopy (SEM). The observations revealed that the friction coefficient of composite depends on the formation and development of a transfer film. The wear mechanism involves polymer matrix wear and fiber wear. The former consists of melting wear and plastic deformation of the matrix, while the latter includes fiber sliding wear, cracking, rupturing, and pulverizing. The contributions of the matrix wear and the fiber wear determine the ultimate wear volume of PA66/PPS/GF composite. In addition, the abrasive action caused by the ruptured glass fiber is also a very important factor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 523–529, 2006     

聚酰胺66改性玻璃纤维增强聚苯硫醚体系的摩擦学性能研究

研究了聚酰胺66(PA66)改性玻璃纤维(GF)增强聚苯硫醚(PPS)（PPS/PA66/GF）复合体系的摩擦因数、磨损体积、磨损后表面的微观形貌及损耗因子峰值、储能模量对摩擦因数的影响。结果表明,PA66的加入显著改善了复合材料的摩擦学性能,当PA66含量为40 %（质量分数,下同）时,磨损最小,为5.24 mm3,相对于PPS+30 %GF(13.60 mm3)下降了61 %;扫描电镜分析磨损表面,随着PA66含量的增加,磨损机理由磨粒磨损转为粘着磨损;复合材料损耗因子峰值越大,摩擦因数越小;初始储能模量越大,摩擦因数越小。     

The Effect of Maleic Anhydride Grafted Styrene-Ethylene-Butylene-Styrene on the Friction and Wear Properties of Polyamide6/Carbon Nanotube Composites

The friction and wear properties of polyamide6 (PA6), polyamide6/carbon nanotube (PA6/CNT) nanocomposites and PA6/maleic anhydride grafted Styrene-ethylene-butylene-styrene (SEBS-g-MA+CNT) nanocomposites was studied by means of a ring-on-block tribometer. The morphologies of the worn surfaces of specimens were observed with a scanning electron microscopy (SEM). All specimen wear increases with increasing load; meanwhile, the friction coefficient decreases. Wear of PA6/CNT is larger than that of PA6. Adding SEBS-g-MA to the PA6/CNT improves the wear resistance. The friction coefficient of PA6/CNT is slightly less than that of PA6 at various loads. The friction coefficient of PA6/(SEBS-g-MA+CNT) is the lowest among PA6, PA6/CNT and PA6/(SEBS-g-MA+CNT).     

Mechanical and tribological properties of PA66/PPS blend. II. Filled with PTFE

The mechanical and tribological properties of 70 vol % PA66/30 vol % PPS blend filled with different content of polytetrafluoroethylene (PTFE) were studied in this paper. It was found that the addition of PTFE impairs the mechanical properties of PA66/PPS blend, but greatly increases the wear resistance and decreases the friction coefficient. When PTFE content exceeds 20 vol %, the friction coefficient of composite is minimum (0.15) and lower than that of pure PTFE under the same conditions (0.22). The lowest wear volume (0.44 mm³) is obtained with PA66/PPS/30 vol % PTFE composite, which decreased by 91% compared with unfilled PA66/PPS blend (4.99 mm³). The topography of transfer film and the elemental distribution were investigated by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS), respectively. Because of the characteristic crystalline structure, PTFE preferentially transferred to the steel ring surface and formed a thin, uniform and firmly adhered transfer layer, which reduced the ability of PA66/PPS blend to transfer and prevent the adhesion between the sample and the couterface. In addition, the superior lubrication of PTFE inhibited the frictional heat melting during sliding. All these aspects are close related to the friction and wear behavior of PA66/PPS/PTFE composite. Upon the addition of PTFE, thermal control of friction regime is not applicable to the PA66/PPS blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 969–977, 2006     

混杂填料增强PA6复合材料摩擦磨损性能

利用M-2000型摩擦磨损试验机考察载荷以及纳米Si_3N_4/SiO_2与玻璃纤维的混合填料对PA6复合材料摩擦磨损性能的影响,用扫描电子显微镜观察分析磨损表面形貌及磨损机理.结果表明:纳米材料与玻璃纤维的协同作用显著改善了材料的摩擦磨损性能,以3%纳米Si_3N_4与玻璃纤维混杂填充耐磨性最佳;以5%纳米SiO_2与玻璃纤维混杂摩擦因数最低.     

Study on the Friction and Wear Behaviors of Modified PA66 Composites

The wear-resistant polyamide 66 (PA66) composites were prepared and the mechanical properties, friction and wear properties were inspected. Results show that GF, PTFE and MoS₂ can improve the mechanical, friction and wear properties of PA66 composites. PTFE is more effective on the friction and wear properties than MoS₂ when GF is 30%wt. The best effect of the modification is 35%wt GF when both PTFE and MoS₂ were added. Friction coefficient first increase, then reduce to be stable as sliding time increases. Friction coefficient and wear mass loss increase as load increases. The main wear mechanisms are fatigue and abrasion wears.     

The Friction and Wear of Aramid Fiber-Reinforced Polyamide 6 Composites Filled with Nano-MoS2

The friction and wear behaviors of aramid-filled PA 6 composites filled with and without nano-MoS₂ were investigated on an end-face tribometer through rubbing against ASTM 1045 steel under dry friction. The experimental results indicated that the wear rate and the friction coefficient of PA 6 decreased with the addition of nano-MoS₂. The friction coefficients of PA 6 composites filled with aramid fiber are lower than those without nano-MoS₂. The main wear mechanisms under dry sliding condition are the plastic deformation and mechanical microploughing. For best combination of friction coefficient and wear rate, the optimal volume content of MoS₂ in the composites appears to be 10 vol %.     

Tribological behavior of polyamide 66‐based binary and ternary composites

Friction and wear characteristics of polyamide 66 (PA66) and the composites of organoclay modified by styrene–ethylene/butylene–styrene triblock copolymer grafted with 1.84 wt% of maleic anhydride (SEBS‐g‐MA) were studied using an Universal Micro Tribometer reciprocating friction and wear tester. The morphologies of the wear tracks of PA66 and the composites were observed using a scanning electron microscope. The results showed that plastic deformation induced by the traction of the harder steel ball occurred on the worn surfaces of PA66 and the composite which were reinforced by SEBS‐g‐MA copolymer. It was found that the average frictional coefficient and specific wear rate of PA66/SEBS‐g‐MA binary composite are lowest under the same conditions. This indicates that toughness and wear resistance of PA66 matrix are improved with the incorporation of SEBS‐g‐MA copolymer. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Effect of transfer film on tribological behavior of polyamide 66‐based binary and ternary nanocomposites

BACKGROUND: In a polymer–metal sliding system, the formation and performance of the transfer film have important effects on the tribological behavior of the polymer. In order to reveal the wear mechanism of polyamide 66 (PA 66) and its composites consisting of styrene–(ethylene/butylene)–styrene triblock rubber grafted with maleic anhydride (SEBS‐g‐MA) particles and organoclay nano‐layers, the tribological behavior and transfer films of polyamide 66 and its composites were investigated under dry sliding. RESULTS: The incorporation of SEBS‐g‐MA rubber particles reduces the wear mass loss of PA 66, while the addition of organoclay nano‐layers increases the wear mass loss. The transfer films formed by neat PA 66 and PA 66/organoclay binary nanocomposite include a dark portion and bright portion. In the dark portion, the transfer film is thicker; in the bright portion, the steel ring surface is exposed. The transfer film formed by PA 66/SEBS‐g‐MA/organoclay ternary nanocomposite is thinner and more uniform than the transfer films formed by the other materials. CONCLUSION: When SEBS‐g‐MA rubber particles and organoclay nano‐layers are added simultaneously to PA 66, the wear resistance of PA 66 can be improved markedly. The main reason is that PA 66/SEBS‐g‐MA/organoclay ternary nanocomposite can form a thin and uniform transfer film on the steel ring surface. Copyright © 2008 Society of Chemical Industry     

Polymorphism in polyamide 66/clay nanocomposites

Polyamide 66/clay nanocomposites (PA66CN) were prepared via melt compounding method by using a new kind of organophilic clay, which was obtained through co-intercalation of epoxy resin and quaternary ammonium into Na-montmorillonite. The silicate layers were dispersed homogeneously and nearly exfoliated in polyamide 66 (PA66) matrix. The introduction of silicate layers induced the appearance of the γ phase in PA66CN at room temperature, more clay loadings would amplify this phenomenon; the addition of clay also changed the structure of the α crystalline phase. The presence of silicate layers increased the crystallization rate and had a strong hetero phase nucleation effect on PA66 matrix. The lower Brill transition temperature of PA66CN can be attributed to the strong interaction between polyamide chains and surfaces of silicate layers.     

Graphite fluoride and fluorographene as a new class of solid lubricant additives for high‐performance polyamide 66 composites with excellent mechanical and tribological properties

Fluorographene (FG) with layer numbers of 3–4 was successfully prepared through facile microwave‐assisted liquid phase exfoliation of raw graphite fluoride (GrF). The raw GrF and the as‐prepared FG were then directly incorporated into polyamide 66 (PA66) by melt processing without using any surfactants. Microstructural, mechanical and tribological properties of the prepared PA66 composites were investigated. Various characterization results showed that both GrF and FG, as novel solid lubricants, can effectively improve the mechanical and anti‐wear performances of the PA66 matrix. It was also found that FG is better at improving mechanical properties and reducing the friction of PA66 than GrF at low concentrations owing to the large surface–volume ratio. The addition of 0.5 wt% FG into PA66 exhibits a ca 13% increase in tensile modulus, ca 5% increase in tensile strength, ca 18% reduction in coefficient of friction (COF) and ca 43% reduction in wear rate. However, at relatively high concentrations, such as 1.0 wt%, GrF shows a better reinforcement effect than FG owing to a uniform dispersion of GrF in the PA66 matrix. The addition of 1.0 wt% GrF into PA66 exhibits a ca 18% increase in tensile modulus, ca 5% increase in tensile strength, ca 37% reduction in COF and ca 46% reduction in wear rate. Wear tests also show that the excellent wear resistance of the PA66 composites is due to the improved mechanical properties and the lubrication of GrF and FG between the worn surfaces. Our current work demonstrates the tremendous potentials of fluorinated carbon materials for enhancing mechanical and anti‐wear properties of polymeric materials. © 2020 Society of Chemical Industry     

Thermal and mechanical properties of PA12/C30B nanocomposites in relationship with nanostructure

This work focuses on the effect of nanoclay mass fraction on the properties of polyamide 12 matrix. Relationships between mechanical, thermal, and structural properties of polyamide 12/Cloisite^® 30B nanocomposites were studied. The material structure, previously described from XRD and TEM experiments, was more thoroughly characterized in the present work using SEM and FTIR techniques. The FTIR results clearly showed that clay galleries are intercalated by PA chains, which leads to a partially exfoliated nanostructure, confirming the TEM observations and the XRD analysis. However, a few micrometric aggregates are evidenced by SEM analysis, particularly at high clay fractions. TGA and DTA measurements showed that the thermal stability of PA12 matrix is slightly modified by the Cloisite^® 30B content. Viscoelastic properties of the nanocomposites in solid‐state were analyzed as functions of strain, frequency, and temperature. The extent of the linear response regime of the material is shown to be sensitive to the amount of clay: nonlinearities appear at lower strain values as the clay mass fraction increases. Both relative dynamical moduli also increase with increasing clay mass fraction, with frequency dependence for the viscous modulus and without frequency dependence for the elastic modulus. Finally, similarities have been pointed out between viscoelastic properties of the nanocomposites in solid and melt states. For example, the percolation threshold is highlighted at the same clay mass fraction, ～2%, in both states. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41938.     

Influence of surface modification of carbon nanotube on microstructures and properties of polyamide 66/multiwalled carbon nanotube composites

The melt‐mixing polyamide 66 (PA66) composite samples that incorporated pure, acid‐ and amine‐functionalized multiwalled carbon nanotubes (MWCNTs) were prepared in order to enhance mechanical and frictional properties of PA66 composites. The homogeneous dispersion of amine‐functionalized MWCNTs (D‐MWCNTs) in PA66 matrix was observed from the significantly uniform morphology of tensile fractured surface of the composites. Differential scanning calorimetry measurement indicates that D‐MWCNTs acted as effective nucleation agent for PA66 matrix and the crystallinity of PA66 was increased. The fracture stress and tensile modulus of the composites were significantly improved with the incorporation of D‐MWCNTs, owing to the good dispersion of D‐MWCNTs. Compared with PA66, the PA66 composites with 1.0 wt% D‐MWCNTs were improved considerably in both wear and friction properties owing to the change of the tribological mechanisms. The good dispersion of D‐MWCNTs in PA66 and good interface compatibility between D‐MWCNTs and PA66 favored the formation of a thin layer on the contact surfaces during wear and friction test, which played an important role in reducing wear and friction of the composite and in suppressing the transverse cracks. These results prove the importance of D‐MWCNTs in a positive change of the mechanical and frictional properties of PA66 composites and suggest the applicability prospect of PA66/D‐MWCNTs composites in engineering components.POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers