화학공학소재연구정보센터
Applied Surface Science, Vol.256, No.11, 3394-3408, 2010
Micro- to nanoscale surface morphology and friction response of tribological polyimide surfaces
Sintered polyimide surfaces that were worn under macroscale conditions at different temperatures, were further characterised by contact-mode atomic force microscopy for getting insight in the tribophysical and -chemical processes at the micro-to nanoscale. Depending on the temperature, either mechanical interaction (23 degrees C < T < 100 degrees C), hydrolysis (120 degrees C < T < 140 degrees C), or imidisation (180 degrees C < T < 260 degrees C) results in different microscale surface characteristics. At low temperatures, surface brittleness and inter-grain fracture has been observed with an almost homogeneous friction pattern. At intermediate temperatures, the formation of a protecting local film leads to smoother surfaces with local lubricating properties. At high temperatures, different topographical and frictional patterns are observed depending on local imidisation or degradation. From AFM scans at the submicronscale, local debris depositions are observed and correspond to surface locations with locally reduced friction. From AFM scans at the nanoscale, polymer chain orientation is observed with formation of zig-zag or stretched molecular conformation: the latter is not induced by purely mechanical surface interactions or hydrolysis, but mainly results from tribochemically induced imidisation at high sliding temperatures. The present investigation describes the influences of local tribological interactions onto the macroscale wear behaviour of a polymer, and therefore aims at contributing to a better understanding of scaling between macro-to nanolevel tribological response. (C) 2009 Elsevier B. V. All rights reserved.