Tribological Performance of Polymer Composites used in Electrical Engineering Applications

Sliding wear performance of 20% mica-filled polyamide 6 (PA6 + 20% mica) and 20% short glass fibre-reinforced polysulphone (PSU + 20 GFR) polymer composites used in electrical applications were investigated using a pin-on-disc wear test apparatus. Two different disc materials were used in this study. These are AISI 316 L stainless steel and 30% glass fibre-reinforced polyphenylenesulphide (PPS + 30%GFR) polymer composite. Wear test was carried out at 10, 20 and 30 N applied load values and 0·5 m/s sliding speed and at ambient temperature and humidity. Different combinations of rubbing surfaces were examined and friction coefficient and specific wear rate values were obtained and compared. For two material combinations used in this investigation, the coefficient of friction shows insignificant sensitivity to applied load values and large sensitivity to material combinations. For specific wear rate, PA6 + 20% mica composite has shown insensitivity to change in load, speed and materials combination while PSU + 20% glass fibre composite has shown high sensitivity to the change in load and material combinations. The friction coefficient of PA6 + 20% mica and PSU + 20 glass fibre rubbing against the AISI 4140 steel disc is between 0·35 and 0·40. In rubbing against PPS + 30% glass fibre their values were between 0·25 and 0·30. Specific wear rate for PA6 + 20% mica and PSU + 20% glass fibre composites are in the order of 10 − 13 to 10 − 14 m2/N. Finally, the wear mechanisms are a combination of adhesive and abrasive wear processes. In terms of application, especially in electrical systems, a substantial contribution was provided to extend switch life. Thus, besides robustness, this also ensured safety for the system and the users against undesirable situations.

Temperature-dependent mechanical properties of polyetherimide composites reinforced by graphene oxide-coated short carbon fibers

Effect of electrodeposited Cu interlayer thickness on characterizations and adhesion force of Ni/Cu/Ni coatings on polyetherimide composite substrates

This research highlights the effect of radiation, chemical and thermal environments on mechanical and thermal properties of polyetherimide (PEI) composites. The tests are conducted on specimens made from PEI and PEI reinforced with modified Carbon Nano Fibre (CNF). The specimens are subjected to gamma radiation doses of 5 MGy, which is equivalent to the cumulative dose of radiation from spent nuclear fuel until the end of complete radioactivity. The exposed samples are further subjected to highly corrosive and thermal environments. Studies under transmission electron microscopy reveal that there is a uniform dispersion of modified CNF in PEI. Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA) indicate that there are no significant changes in thermal properties of PEI and PEI composite when exposed to aggressive environments. It is observed that there is a marginal loss in the tensile strength of polymeric samples when exposed to gamma radiation and thermal environments. PEI samples when subjected to alkaline corrosive environments show significant loss in the tensile strength. There is a significant decrease in the molecular weight of PEI under alkaline corrosive environments as seen from Gel Permeable Chromatography (GPC).

Hexagonal boron nitride (h‐BN) micro‐platelets were surface‐functionalized by sulfuric acid (SA). Such modified h‐BN powders were mixed with thermoplastic polyether imide (PEI) to prepare flexible composite films using a solution casting method. After surface modification, the h‐BN powders were uniformly dispersed in the PEI matrix. The thermal conductivity of the flexible composite materials was significantly improved, with a 60% increase over that of pure PEI. The mechanical properties of the composites were also measured and discussed. The Young's modulus of the h‐BN/PEI composites was increased from 1.15 GPa for pure PEI to 1.62 GPa for the h‐BN/PEI composite with a filling ratio 10 vol%. As compared to pure PEI film, the electrical breakdown strength of the composites with 5 vol% h‐BN increased from 45.3 to 55.3 kV/mm. Our results show that the surface‐modified h‐BN filler is effective in improving the thermal conductivity and insulation performance of PEI‐based composites.

Control of alignment of h-BN in polyetherimide composite by magnetic field and enhancement of its thermal conductivity

Tribological properties of neat polyetherimide (PEI), glass, carbon fiber, and solid lubricants filled PEI composites are presented in this article. The aim of this study was to investigate the friction and wear properties of these composites under dry oscillating sliding condition at room temperature (RT) as well as at elevated temperature (120°C). The polymer specimens were made to oscillate against steel cylinder as a counterpart. The friction and wear properties of PEI and composites were strongly influenced by the temperature. Incorporation of carbon fiber in the PEI matrix has increased the wear rate at RT, while at elevated temperature this trend was opposite. Abrasive action of carbon fibers has severely damaged the counterpart and resulted in accelerated wear of the composite at RT. Solid lubricants filled (PTFE, MoS2, graphite) along with glass fiber is beneficial in improving the friction and wear performance of the PEI composite at RT, whereas at elevated temperature wear performance was deteriorated. Tribological performance of neat PEI and glass fiber composite was similar with each other at RT. Scanning electron micrographs and optical micrographs of the worn polymer specimens and the steel cylinders was used to study the possible wear mechanisms. The present test results were also compared with data available on the reciprocating wear of PEI and composites in the literature and trends have been reported. POLYM. COMPOS., 38:48–60, 2017. © 2015 Society of Plastics Engineers

Purpose This study aims to investigate and compare the tribological behavior of two high-performance polymers, ultra-high-molecular weight polyethylene (UHMWPE) and polyetheretherketone (PEEK), under dry sliding conditions against steel and various polyetherimide (PEI)-based polymer counterfaces. Design/methodology/approach Pin-on-disk wear tests were carried out using the UHMWPE and PEEK pins sliding against four different counterfaces of general purposed (GP)-PEI, wear resistant (WR)-PEI, glass fiber-reinforced PEI (PEI + 20% GFR) and AISI 304 L stainless steel. The experiments were conducted under normal loads of 20, 40 and 60 N at a constant sliding speed and distance. The coefficient of friction (COF), specific wear rate (SWR) and dominant wear mechanisms were evaluated based on the experimental measurements and optical microscopy observations. Findings The UHMWPE consistently exhibited lower COF and specific wear rate values than those of the PEEK, under all test conditions. Its best tribological performance was achieved at a load of 60 N against the GP-PEI counterface, yielding the COF and SWR values of 0.0728 and 7.96 × 10–15 m²/N, respectively. For the PEEK, the optimum values of the COF and SWR were obtained as 0.1856 and 8.79 × 10–15 m²/N, respectively also against the GP-PEI. The superior performance of the UHMWPE was mainly attributed to its self-lubricating behavior and the formation of a stable transfer film. However, the PEEK exhibited higher and more unstable friction behavior, particularly when sliding against the PEI + 20% GFR and steel counterfaces. Originality/value Unlike most previous studies focusing primarily on the metal–polymer tribological pairs, this study provides a comprehensive comparative evaluation of polymer–polymer and polymer–metal interfaces. The findings demonstrate that the UHMWPE outperforms the PEEK in the dry sliding applications and offer valuable insights for the rational selection of tribo-pairs in the engineering applications.

Interfacial Adhesion and Microfailure Modes of Electrodeposited Carbon Fiber/Epoxy–PEI Composites by Microdroplet and Surface Wettability Tests

Effect of hydrogen plasma-mediated surface modification of carbon fibers on the mechanical properties of carbon-fiber-reinforced polyetherimide composites

In this study, we investigated the thermal conductivities and mechanical properties of polyetherimide (PEI) composites using polyimide (PI)-coated h-BN (PI-BN) particles. We found that PI-coated h-BN effectively increased adhesion with the PEI matrix, imparting enhanced mechanical and thermal stability and thermal conductivity with increasing BN content. The thermal conductivity of the PEI composite containing 60 wt% PI-BN was 3.3 W m(-1) K(-1), while the thermal conductivity of the PEI/BN composite without modification was 2.6 W m(-1) K(-1). The PEI/PI-BN composites show higher impact strengths than the PEI/BN composites because of less BN particle agglomeration and good wettability between PEI and h-BN. The results indicate that the PI-coated BN incorporated into the PEI matrix effectively enhances the thermal conductivity and mechanical properties of the PEI composites.

Mechanical and tribological properties of hybrid fabric–modified polyetherimide composites

Friction and wear performance of pure and glass fibre reinforced poly-ether-imide on polymer and steel counterface materials

Effects of carbon nanotube-polydopamine hybridization on the mechanical properties of short carbon fiber/polyetherimide composites

Polyetherimide composite is one of the most non-flexible and lightest composite materials which is difficult to machine by conventional machining process. This material has widespread applications in mechanical engineering, industries, etc. Polyetherimide composite has excellent properties of high-temperature stability, specific stiffness performance, high durability, corrosion resistance, wear resistance, high conductivity and self-lubrication. In the present investigation, 24-layered structured matrix was constructed and properties such as hardness and quality of carbon-fabricated composite structure using dry sliding method have been examined. Further, to testify its applicability in aviation and automobile industry the simulations were illustrated to comment on its mechanical strength. There is a reduction in coefficient of friction by 66.67% noticed at 70 N load, which is associated with surface modifications from frictional heating. Further, to examine and evaluate material’s stress and strain strengths a set of simulations were carried out with a maximum von Mises stress of 2145.4 GPa on ANSYS Workbench 18.1. Finally, it has been concluded that as the layers of the carbon fiber content increase, hardness along with wear resistance of reinforced carbon fiber for polyetherimide composites increases.