Study of mechanical and tribological properties of nylon 66‐titanium dioxide microcomposite

Nylon 66 microcomposites with various weight percentage of titanium dioxide (TiO₂) were prepared by a twin screw extruder and investigated for mechanical and tribological properties. Mechanical properties of the composite such as tensile strength/modulus, flexural strength/modulus, impact, and compressive strength first showed an increase up to 6 wt% TiO₂ followed by a decrease at higher filler loading. The value of heat deflection temperature increased with the increase in wt% of TiO₂. Sliding wear tests were performed on pin‐on‐disk equipment under different loads, sliding velocity, and sliding distance combinations. It was found that micro‐TiO₂‐Nylon 66 composite exhibited reduced wear and coefficient of friction up to 6 wt% TiO₂. Micro‐TiO₂ at 2 wt% was most effective in improving the tribological properties of plain nylon 66. The worn surfaces were examined by scanning electron microscopy to understand the wear mechanism. The optimal combination from 2 wt% to 6 wt% micro‐TiO₂‐Nylon 66 can be used depending upon the application requiring improvement in tribological or mechanical properties, respectively.     

Preparation of Cu nanoparticles-modified PA6 composites using CuO as filler

This work focuses on the preparation of copper nanoparticles-modified polyamide 6 composites (denoted as nano-Cu/PA6) by in situ polymerization, with which cupric oxide as metallic copper source is directly reduced to metallic copper in the process of the opening-ring polymerization of ε-caprolactam only using the reducing atmosphere of reaction system. The obtained composites are characterized by means of transmission electron microscopy, X-ray diffraction, laser granulometry instrument, and ultraviolet–visible absorption spectroscopy. Moreover, the friction and wear resistance, mechanical strength, and antistatic performance of as-prepared composites are also readily evaluated. The results show that cupric oxide as filler is reduced to metallic copper and the as-reduced copper nanoparticles with 4–5-nm-size clusters separately disperse in polyamide 6 (PA6) matrix. Additionally, the addition content (mass fraction) of cupric oxide has significant effect on the crystalline form of PA6, and γ crystalline form of PA6 is predominant when higher dosage of CuO is introduced to fabricating nano-Cu/PA6 composites. Moreover, introducing a proper amount of CuO filler favors to generate nano-Cu/PA6 composites with improved mechanical properties and wear resistance. Particularly, nano-Cu/PA6 composite prepared at a CuO content of 0.5 % possesses the best tensile strength and wear resistance, showing promising application as a functional polymer–matrix composite.     

Fabrication of thermoplastic composites using fly-ash a coal and hollow glass beads to study their mechanical,thermal, rheological,morphological and flame retradency properties

Thermoplastic polycarbonate (PC) and nylon 6 (NY) composites with cenosphere and hollow glass beads were prepared and their mechanical, rheological, thermal and flame retardency properties were studied. The flexural behavior of the composites increased after loading with cenosphere and hollow glass beads. The tensile strength of the PC composites was enhanced up to 80 N mm^–2 as compared to pure PC while no remarkable change was observed in case of nylon 6 composites. Study of thermogravimetric Analysis (TGA) showed that the thermal stability of all the composites (Polycarbonate/cenosphere, Polycarbonate/hollow glass beads, Nylon 6/cenosphere and Nylon 6/hollow glass beads) increased. It was concluded that both the fillers enhanced the non-flammability of the polymers. Limiting oxygen index (LOI) value of all the composites showed an increase with increase in the concentration of filler. The optimal results of LOI and UL 94 were observed in composites with 8% cenosphere and 12 % cenosphere in case of Nylon 6. Cenosphere led to superior mechanical properties of polycarbonate and nylon 6 in comparison to hollow glass beads which suggested the composites can find use in automotive, industrial, pump component and for manufacturing of light weight parts in aeronautic industry at lower economic value.     

The Wear Resistance of Composite Materials Based on Ultra-High-Molecular-Weight Polyethylene with Fillers of Various Types

The tribological properties and wear resistance under different action of composite materials based on of ultra-high-molecular-weight polyethylene (UHMWPE) and fillers of various types such as organomodified montmorillonite (MMT), graphite nanoplates (GNP), molybdenum disulfide, and shungite prepared via polymerization in situ are studied. According to the obtained results, the introduction of these fillers to UHMWPE in the amount of 0.4–7 wt % has almost no effect on the value of the coefficient of sliding friction on steel in the mode of dry friction. Composites with GNP, MoS₂, and shungite are characterized by a significant (two- to threefold) increase in the wear resistance in the case of sliding friction on steel. The abrasive wear of composites in the case of friction on an abrasive paper is substantially affected by the type of filler, the use of MMT was the most effective for increasing the wear resistance of composites. In the case of a highspeed impact effect of water–sand suspensions all the studied composites are characterized by increased wear resistance in comparison with industrial UHMWPE at a low concentration of fillers and by an increase in the wear with the increase of the filler content.     

Mechanical properties and frictional resistance of Al composites reinforced with Ti_3C_2T_x MXene

Two-dimensional(2D) Ti_3C_2T_x MXene is an attractive additive not only used in base oil due to its low friction coefficient,but also used in composites due to its high aspect ratio and rich surface functional groups.So far there has been intense research into polymer matrix composites reinforced with Ti_3C_2T_x,Here we report on the use of 2D Ti_3C_2T_x to enhance the mechanical and frictional properties of Al matrix composites.Ti_3C_2T_x/Al composites were designed and prepared by pre s sureless sintering followed by hot extrusion technique.The prepared composites exhibit a homogeneous distribution of Ti_3C_2T_x.The Vickers hardness and the tensile strength continuously increase with increasing Ti_3C_2T_x content.A hardness of 0.52 GPa and a tensile strength of 148 MPa were achieved in the 3 wt% Ti_3C_2T_x/Al composite.The frictional properties of pure Al and the Ti_3C_2T_x/Al composite were comparably studied under dry sliding.A low friction coefficient of 0.2,twice lower than that of pure Al,was achieved in the 3 wt%Ti_3C_2T_x/Al composite.Ti_3C_2T_x acting as a solid lubricant reduces the abrasive wear in the composite,improving the frictional properties of Al matrix composites.     

Effect of nano‐modified SiO2/Al2O3 mixed‐matrix micro‐composite fillers on thermal,mechanical, and tribological properties of epoxy polymers

Thermo‐mechanically durable industrial polymer nanocomposites have great demand as structural components. In this work, highly competent filler design is processed via nano‐modified of micronic SiO₂/Al₂O₃ particulate ceramics and studied its influence on the rheology, glass transition temperature, composite microstructure, thermal conductivity, mechanical strength, micro hardness, and tribology properties. Composites were fabricated with different proportions of nano‐modified micro‐composite fillers in epoxy matrix at as much possible filler loadings. Results revealed that nano‐modified SiO₂/Al₂O₃ micro‐composite fillers enhanced inter‐particle network and offer benefits like homogeneous microstructures and increased thermal conductivity. Epoxy composites attained thermal conductivity of 0.8 W/mK at 46% filler loading. Mechanical strength and bulk hardness were reached to higher values on the incorporation of nano‐modified fillers. Tribology study revealed an increased specific wear rate and decreased friction coefficient in such fillers. The study is significant in a way that the design of nano‐modified mixed‐matrix micro‐composite fillers are effective where a high loading is much easier, which is critical for achieving desired thermal and mechanical properties for any engineering applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of clay and surface plasma‐treated carbon fiber on wear behavior of thermoplastic POM composites

In engineering applications, experimental data and insight from scientific investigations on wear properties of polyoxymethylene (POM) composites are important for engineers to understand how to design and formulate POM materials with high resistance to wear. In this work, clay and carbon fiber were utilized and incorporated into POM and the mechanical and wear properties, in specific wear rate, were then assessed. The experimental results suggested that the addition of clay increased the tensile modulus and strength. The mechanical and wear properties of POM composites were found to improve with the addition of the carbon fiber. Carbon fiber/clay/POM composite exhibited the lowest specific wear rate and friction coefficient.     

Thermal resistance and mechanical stability of tungsten oxide filled polymer composite radiation shields

Abstract

The influence of tungsten oxide on thermal and mechanical properties of Isophthalic polyester was studied in detail. Ultrasonication technique was successful in dispersing WO₃ filler particles upto 40?wt% into the polymer matrix and was confirmed through the Scanning Electron Microscopy technique. The mechanical strength of the composites was found to increase with increase in the WO3 content and is acting as a reinforcer. About 77.4%, 65.4% and 7–8 times increase was observed in tensile, flexural and compressive strength respectively with respect to pristine. The thermogram of the composites reveal two stages of degradation. Maximum weight loss was observed in the first stage of degradation in almost all the composites. The initial degradation temperature of the composites range from 151?°C–226?°C. Activation energy was estimated using Horowitz–Metzger kinetic theory and was found to range from 25.31 to 78.58?kJ/Mol. The 50?wt% WO3 filled composite exhibits excellent thermal stability and mechanical strength. Thus, WO₃ filler particles were successful in enhancing the thermal and mechanical strength of Isophthalic polyester.     

Comparative study of the mechanical and wear performance of short carbon fibers and mineral particles (Wollastonite,CaSiO3) filled epoxy composites

To improve the mechanical and tribological performance, two kinds of wollastonite fillers (fine or coarse) and short carbon fibers (5–15 vol %) were, respectively, incorporated into an epoxy resin. Fine wollastonite fillers remarkably enhanced the flexural modulus, strength, and toughness of the resin at some filler contents (i.e., 10 vol %) simultaneously, while coarse wollastonite fillers and short carbon fibers impaired most of mechanical properties except the modulus. The small particle size, low aspect ratio as well as the good adhesion to the epoxy matrix of the fine wollastonite particles are believed to be responsible for the improved strength and toughness. Tribological tests were performed under sliding and low amplitude oscillating wear conditions. All fillers enhanced the wear resistance and reduced the sliding coefficient of friction but to a different extent. Under sliding wear conditions, fine wollastonite particle‐filled epoxy displayed the highest wear resistance because of the formation of an effective transfer film and the low abrasiveness of the fillers. Under low amplitude oscillating wear conditions, both wollastonite fillers showed much higher wear resistance than short carbon fibers regardless of the filler content. The better adhesion between the wollastonite fillers and the epoxy matrix is responsible for the higher wear resistance under oscillating conditions. The wear tracks were inspected by microscopy to analyze the corresponding wear mechanisms. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 854–863, 2006     

Study on the friction and wear behavior of surface‐modified carbon nanotube filled carbon fabric composites

The functionalization of multi‐walled carbon nanotubes (MWNTs) was achieved by grafting furfuryl amine (FA) onto the surfaces of MWNTs. Furthermore, the functional MWNTs were incorporated into carbon fabric composites and the tribological properties of the resulting composites were investigated systematically on a model ring‐on‐block test rig. Friction and wear tests revealed that the modified MWNTs filled carbon fabric composite has the highest wear resistance under all different sliding conditions. Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA) revealed that MWNTs were successfully functionalized and the modification led to an improvement in the dispersion of MWNTs, which played an important role on the enhanced tribological properties of carbon fabric composites. It can also be found that the friction and wear behavior of MWNTs filled carbon fabric composites are closely related with the sliding conditions such as sliding speed, load, and lubrication conditions. Copyright © 2010 John Wiley & Sons, Ltd.     

Friction and wear behavior of PI and PTFE composites for ultrasonic motors

High‐performance polymer‐based frictional materials have become increasingly important to improve the mechanical output properties of ultrasonic motors. This study discussed the friction and wear behavior of 2 dominating frictional materials of polymer composites for ultrasonic motors, polyimide (PI), and polytetrafluoroethylene (PTFE) filled by aramid fibers (AF) and molybdenum disulfide (MoS₂). To explore the wear mechanisms, the tribo‐pair contact stress was theoretically characterized, and the interface temperature rise was numerically predicted. The predictions showed that the flash temperature on asperity tips could reach the glass transition temperature of the polymer materials. The experimental results indicated that the contact stress and sliding speed have a small effect on the friction of the PI composite but influence considerably the friction of the PTFE composite. A higher contact stress brings about a higher specific wear rate, but a higher sliding speed reduces the wear rate. Compared with AF/MoS₂/PTFE, the AF/MoS₂/PI has much better tribological performance under high loads and speeds.     

The flexural and tribological properties of UHMWPE composite filled with plasma surface‐treated wood fibers

In this paper, the wear performance of an ultra‐high molecular weight polyethylene composites filled with wood fiber were studied using a pin‐on‐disc method. The effects of surface treatment of wood fiber and sliding load and on the friction and wear of the wood fiber/UHMWPE composite are reported. The test results showed that the sliding load is an important controlling factor; its effect is diminished when the wood fiber is modified.     

Synthesis and Characterization of Polyester-Based Nanocomposite

Recently, unsaturated polyester resin (UPR) and silica nanocomposite prepared by mechanical process is the one of the promising composite materials. In this study, the effects of silica as filler on mechanical, thermal, and morphological properties of unsaturated polyester-based composite were investigated. Mechanical properties such as tensile strength, elongation and Young's modulus increase with the addition of silica nanoparticle up to 1.0 wt%, and then decrease, over 1.0 wt%. Morphological surface of composite reveals that well-dispersed silica in the matrix occurred in low concentration. However, increasing of silica concentration causes aggregation of particles. Enhancement of mechanical properties strongly corresponds to strong adhession force of silica with the matrix and it influnced by well-disperse silica particles on the whole surface of composite. Thermal characterization and analysis of major functional group of the composites were also performed and described in this paper.     

Optimization of tribological behavior of nano clay particle with sisal/jute/glass/epoxy polymer hybrid composites using RSM

The tribological properties are one of the most significant properties in many automobile components such as clutch plate, break shoe, engine liner, piston pin, etc. At present work, attempt on nano clay is loaded with natural fibers (sisal and jute), artificial fiber (E‐glass), and epoxy resin. In this investigation, the specific wear rate and coefficient of friction are analyzed by pin on disc apparatus under dry sliding conditions. The experiment design carried by Box–Behnken design on design of experiment techniques with influence wear parameters, namely, filler content, applied load, sliding distance, and sliding velocity; its responses are analyzed by response surface methodology. The regression mathematical models performed for all the responses, and the most influential factors determined by analysis of variance technique, S/N ratio. The results indicate that the coefficient of friction and specific wear rates are minimized with the addition of filler content to the developed composites and further increasing, the response of composites may be varied. Copyright © 2017 John Wiley & Sons, Ltd.     

The effect of granite powder on mechanical,structural and water absorption characteristics of alkali treated cordia dichotoma fiber reinforced polyester composite

Environmental and societal concerns such as pollution, disposal of solid waste, requirement of different conflicting properties for materials in varied applications and cost are the main reasons for the development of new materials from the existing materials. The concerns may possibly be overcome by substituting natural fibers for synthetic fibers. In this study, a hybrid composite was developed by reinforcing the natural fiber “cordia dichotoma” and filler “granite powder” into polyester resin. This composite was fabricated using hand lay-up method. Cordia dichotoma fibers were surface treated with NaOH for reducing the hydrophilic nature of the fiber. Unused industrial waste in the form of granite powder obtained from the granite polishing industry is utilized as reinforcement in polymer composite. The hybrid composite was prepared by reinforcing a constant cordia dichotoma fiber content of 20 wt % and varying the granite powder weight (wt. %) percentages (0, 5, 10, 15, and 20) into polyester resin. Mechanical properties (tensile, flexural and impact) of hybrid composites were investigated. The novelty of this work lies in utilization of granite powder sourced from industrial waste utilized as filler material. Granite, as one of the hard materials, may improve wear and other mechanical properties. Following the results obtained, granite powder could be evidenced as a good filler material for the betterment of composites mechanical properties. Also, the ability of this filler material is proved in decreasing water absorption and chemical resistance. Scanning electron microscope (SEM) analysis was performed to investigate the bonding and distribution of granite powder within both the fiber as well as resin in the composite. Besides, the presence of chemical functional groups in the composite was traced by Fourier transform Infrared spectroscopy (FTIR). Also, Thermo-gravimetric analysis (TGA) was carried out and the composite was found to be thermally stable up to 415 °C.     

五种植物纤维粉填充不饱和聚酯树脂复合材料的性能对比

以芝麻秸秆粉、水稻秸秆粉、玉米芯秆粉、菠萝叶粉、甘蔗渣粉五种不同植物纤维粉为填充体、不饱和聚酯树脂(UPR)为基体制作植物纤维粉/UPR复合材料,对比研究了秸秆种类对复合材料密度、力学性能及吸水性能的影响。结果表明,植物纤维粉粒径为100目、添加量为UPR用量的10%时,芝麻秸秆粉/UPR复合材料的综合力学性能最好,拉伸强度、弯曲强度和冲击强度分别为41.320 MPa、67.467 MPa和2.815 KJ/m^2,且每一浸泡阶段吸水率均最低。     

Preparation and Characterization of Copper Nanowire/Polyamide 6 Nanocomposites and Its Properties

Copper nanowire/polyamide 6 (denoted as nano-Cu/PA6) nanocomposites were readily prepared via in situ polymerization in reducing atmosphere. The microstructure, phase composition, and chemical state of typical elements of as-prepared nano-Cu/PA6 nanocomposites were analyzed by transmission electron microscopy, and X-ray diffraction, while their thermal stability and crystallization behaviors were evaluated by thermogravimetric analysis and differential scanning calorimetry. Moreover, the mechanical strength of as-prepared nano-Cu/PA6 nanocomposites was determined with a universal testing machine, and their friction and wear behaviors were evaluated with an MRH-3 high speed block-on-ring test rig. Findings indicate that copper nanowire is coated by surrounding molecular chains of PA6 and well disperses in the polymeric matrix. Besides, copper nanowire consists of metallic copper, which indicates that copper nanowire coated by PA6 matrix has good chemical stability and is not oxidized during the preparation of the title nanocomposites under high-temperature reactions. Furthermore, copper nanowire filler is able to remarkably improve the mechanical strength and wear resistance of polyamide 6. Particularly, nano-Cu/PA6 composite containing 0.5% (mass fraction) copper nanowire possesses the maximum tensile strength (its tensile strength is higher than that of pure PA6 by 77.41%); and its friction coefficient and wear scar diameter are also much smaller than those of PA6.     

Waste marble dust-filled sustainable polymer composite selection using a multi-criteria decision-making technique

This research works with the optimal design of marble dust-filled polymer composites using a multi-criteria decision-making (MCDM) technique. Polylactic acid (PLA) and recycled polyethylene terephthalate (rPET)-based composites containing 0, 5, 10, and 20 wt% of marble dust were developed and evaluated for various physicomechanical and wear properties. The results showed that the incorporation of marble dust improved the modulus and hardness of both PLA and rPET. Moreover, a marginal improvement in flexural strength was noted while the tensile and impact strength of the matrices were deteriorating due to marble dust addition. The outcomes of wear analysis demonstrated an improvement in wear resistance up until 10 wt% filler reinforcement, after which the incidence of dust particles peeling off from the matrix was observed, thereby reducing its efficiency. The best tensile modulus of 3.23 GPa, flexural modulus of 4.39 GPa, and hardness of 83.95 Shore D were obtained for 20 wt% marble dust-filled PLA composites. The lowest density of 1.24 g/cc and the highest tensile strength of 57.94 MPa were recorded for neat PLA, while the highest impact strength of 30.94 kJ/m² was recorded for neat rPET. The lowest wear of 0.01 g was obtained for the rPET containing 5 wt% marble dust content. The experimental results revealed that for the examined criteria, the order of composite preference is not the same. Therefore, the optimal composite was identified by adopting a preference selection index-based MCDM technique. The findings demonstrated that the 10 wt% marble dust-filled PLA composite appears to be the best solution with favorable physical, mechanical, and wear properties.     

Cure characteristics and properties of NBR composites filled with co‐precipitates of black liquor and montmorillonite

Acrylonitrile‐butadiene rubber (NBR) composites filled with co‐precipitates of black liquor and montmorillonite (CLM) were prepared by mechanical mixing on a two‐roll mill. The cure characteristics, mechanical properties, thermal properties, and thermo‐oxidative aging properties of NBR/CLM composites were evaluated. Scanning electron microscopy and transmission electron microscopy showed that the filler particles were well dispersed in the NBR/CLM composites. The scorch time and optimum cure time increase with increasing filler loading. A remarkable enhancement in tensile strength, elongation at break, 300% modulus, and shore “A” hardness was also observed. When the loading of CLM was 40 parts per hundred rubbers, it showed about seven times increase in tensile strength, about 1.8 times increase in elongation at break, about three times increase in 300% modulus, and about 1.3 times increase in shore A hardness, respectively, as compared with those of pure cured NBR. Thermal properties and thermal oxidative aging properties, in general, were also improved with loading of this novel filler. Copyright © 2011 John Wiley & Sons, Ltd.     

Mechanical,dynamic mechanical,and thermal analysis of Shorea robusta-dispersed polyester composite

The influence of Shorea robusta natural filler loading (5, 10, 15, 20, and 25 v/v%) on the mechanical, dynamic mechanical, biodegradability, and thermal stability of the polyester composite was analyzed. The composites were fabricated using hand lay-up method. The maximum mechanical properties, storage modulus, and glass transition temperature were observed for the composite with 20 v/v% filler. The peak height of Tanδ was found to be lesser for the same. Thermal analysis results revealed that the thermal stability of composite increased with the incorporation of Shorea robusta as natural filler. Biodegradability testing showed that the addition of filler resulted in weight loss of the composite under soil burial test.