Retracted: Influence of organic montmorillonite nanoparticles on the microstructures and thermal and tribological properties of polyethersulfone and polytetrafluoroethylene composites

Abstract

Because of high wear rate and low thermal deformation temperature, the generalization and application of polytetrafluoroethylene (PTFE) in the field of tribology is restrained to a certain extent. In order to improve the wear resistance and thermal stability of this self‐lubricating polymer, organic montmorillonite (OMMT) nanoparticle reinforced polyethersulfone (PES) and PTFE ternary composites were prepared by the cold molding and vacuum sintering technology. The effects of sodium montmorillonite (Na‐MMT) and OMMT on the microstructures, thermal stabilities and tribological properties of PTFE composites were comparatively studied. The results show that the thermal stability of the PES/PTFE composites is clearly improved by the incorporation of OMMT nanoparticles. Not only the friction coefficients but also the wear rates of OMMT/PES/PTFE composites are less than those of Na‐MMT/PES/PTFE composites under identical tribological tests. Of all these PTFE composites, the PES/PTFE composite containing 10.0 wt% OMMT nanoparticles exhibits the best friction and wear properties (μ = 0.14, k = 5.78 × 10−15 m3 N–1 m−1). This can be attributed to the existence of a polymer multicomponent layer consisting of PTFE, PES and OMMT on the composite surface as well as the formation of uniform PTFE transfer film on the worn surfaces of metal counterparts.

Tribological Effects of Quaternary Ammonium-Functionalized Montmorillonite as Water-Based Additives

“…To confirm the intercalation structure and interlayer spacing after intercalation, Bragg’s equation (2 d sin θ = nλ , where d is the interplanar spacing; θ is the angle between the incident X-ray and the corresponding crystal face; λ is the wavelength of the X-ray (λ = 1.5418 Å); n is the order of diffraction, n = 1) was used to calculate the layer spacing for MMT nanoparticles before and after QAS intercalation, which is denoted as the d -value. Compared with Na-MMT, the diffraction peak corresponding to the 001 crystal face of the modified MMT was obviously shifted to the left, which proved the successful intercalation of QAS . The d001-value of Na-MMT was 1.207 nm, which implied an atypical Na + form within the interlayer spacing of MMT.…”

“…Compared with Na-MMT, the diffraction peak corresponding to the 001 crystal face of the modified MMT was obviously shifted to the left, which proved the successful intercalation of QAS. 20 The d001-value of Na-MMT was 1.207 nm, which implied an atypical Na + form within the interlayer spacing of MMT. Due to the larger ionic radius of the quaternary ammonium cations, the layer spacings of Im16-MMT and Py16-MMT was extended to 1.339 and 1.356 nm, respectively.…”