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The running‐in and steady‐state coefficient of friction of some engineering thermoplastics
Author(s) -
Benabdallah S. H.
Publication year - 1993
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760330203
Subject(s) - materials science , polyoxymethylene , composite material , steady state (chemistry) , polyethylene , coefficient of friction , friction coefficient , polyamide , surface finish , surface roughness , thermodynamics , plane (geometry) , tribology , polymer , chemistry , physics , geometry , mathematics
The dry friction properties of three engineering thermoplastics, ultra high‐molecular‐weight polyethylene (UHMWPE), polyoxymethylene (POW) and polyamide 66 (PA 66), have been investigated using a plane on plane contact. During running‐in, the steady‐state of the friction coincides with stable values for the surface temperature of the slider. The proper trend as well as the correct order of magnitude are observed between the measured surface temperatures and those calculated using the equation of Lancaster. The increase of the run‐in friction as function of the P v factor could be well correlated by μ( t ) = μ ss − P v −n exp(− 2 10 4 t ), where μ ss is the steady‐state value of the coefficient of friction, n is a constant depending on the material tested. A decrease of μ ss with increasing load for UHMWPE and POM indicates that friction is primarily the result of adhesion. However, for the PA 66, the opposite is valid, assuming that in this case the high T g of this material may play an important role. Friction increases as the rugosity of specimen diminishes and as speed increases. Finally, the coefficient of friction could be well correlated by μ = kP m exp(β v ) where k , m , and β are constants depending on roughness and type of material.