Effects of PTFE micro-particles on the fiber-matrix interface of polyoxymethylene/glass fiber/polytetrafluoroethylene composites

Reinforcing polyoxymethylene (POM) with glass fibers (GF) enhances its mechanical properties, but at the expense of tribological performance. Formation of a transfer film to facilitate tribo-contact is compromised due to the abrasiveness of GF. As a solid lubricant, for example, polytetrafluoroethylene (PTFE) significantly improves friction and wear resistance. The effects of chemically etched PTFE micro-particles on the fiber-matrix interface of POM/GF/PTFE composites have not been systematically characterized. The aim of this study is to investigate their tribological performance as a function of micro-PTFE blended by weight percentage. Samples were prepared by different compositions of PTFE (0, 1.7, 4.0, 9.5, 15.0 and 17.3 wt.%). The surface energy of PTFE micro-particles was increased by etching for 10 min using sodium naphthalene salt in tetrahydrofuran. Tribological performance was characterized through simultaneous acquisition of the coefficient of friction and wear loss on a reciprocating test rig in accordance to Procedure A of ASTM G133-95. Friction and wear resistance improved as the micro-PTFE weight ratio was increased. Morphology analysis of worn surfaces showed transfer film formation, encapsulating the abrasive GF. Energy dispersive X-ray spectroscopy (EDS) revealed increasing PTFE concentration from the GF surface interface region (0.5, 1.0, 1.5, 2.0, 2.5 µm)

Optimization of mechanical properties for polyoxymethylene/glass fiber/polytetrafluoroethylene composites using response surface methodology

This paper investigated the effects of polytetrafluoroethylene (PTFE) micro-particles on mechanical properties of polyoxymethylene (POM) composites. Since PTFE is immiscible with most polymers, the surface was etched using sodium naphthalene salt in tetrahydrofuran to increase its surface energy. The effects of two variables, namely PTFE content and PTFE etch time, on the mechanical properties of the composite were studied. Experiments were designed in accordance to response surface methodology (RSM) using central composite design (CCD). Samples were prepared with different compositions of PTFE (1.7, 4.0, 9.5, 15.0, or 17.3 wt %) at different PTFE etch times (2.9, 5.0, 10.0, 15.0, or 17.1 min). Four mechanical properties of the POM/GF/PTFE composites, that is, strength, stiffness, toughness, and hardness, were characterized as a function of two studied variables. The dependency of these mechanical properties on the PTFE etch conditions was analyzed using analysis of variance (ANOVA). Overall desirability, D global index, was computed based on the combination of these mechanical properties for POM/GF/PTFE composites. The D global index was found to be 87.5%, when PTFE content and PTFE etch time were 6.5% and 10 min, respectively. Good correlation between experimental and RSM models was obtained using normal probability plots

Electrochemical performance of binder-free NiO-PANI on etched carbon cloth as active electrode material for supercapacitor

Binder free electrode for supercapacitor application was successfully fabricated which consists of carbon cloth‑nickel oxide-polyaniline (EC-NiP). The composite electrode was prepared by growing NiO on EC via hydrothermal followed by the electrodeposition of PANI. The crystallite sizes of NiO were varied from 5.73 nm to 17.81 nm over the temperature range of 200 to 500 °C. The optimized electrode, heated at 300 °C (NIP300) showed good specific capacitance of 192.31 Fg−1 with energy density of 21.63 mWhkg−1 and 4.81 Wkg−1 of power density at 0.5 Ag−1 current density in 0.5 M H2SO4 electrolyte. The symmetrical NIP300//PVA + 0.5 M H2SO4//NIP300 cell exhibit excellent reversibility where the specific capacitance retained 72% of the initial value after 4500 cycles

Fabrication of polyaniline nanorods on electro-etched carbon cloth and its electrochemical activities as electrode materials

In this work, polyaniline (PANI) nanorods were deposited on electro-etched carbon cloth (EC) by facile electrodeposition method with the existence of purified aniline and sulfuric acid. Various deposition potentials were applied to achieve a good electrochemical performance of EC-PANI electrode. Different applied potentials resulted in different morphologies of PANI deposits and studied by field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). X-ray diffraction (XRD) and Fourier transform infrared (FTIR) characterizations were used to confirm the deposition of PANI on the EC substrate. The optimized PANI nanorods electrode exhibited an excellent specific capacitance of 357.14 Fg−1 with an energy density of 40.18 Wh kg−1 and a power density of 1.28 Wkg−1 at a current density of 0.5 Ag−1 in 0.5 M H2SO4 electrolyte. A symmetrical cell of P1.4//PVA + 0.5 M H2SO4//P1.4 has recorded a good cycling stability with 95 and 88% capacitance retention at current densities of 200 and 300 mAg−1. EC-PANI electrode can be used as a scalable solution for high-performance energy storage devices. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature