Boundary lubrication of glass: rubber sliding contacts

Polymer brush coatings represent a promising class of coatings for friction control [1], especially in a humid environment [2]. A study on the feasibility of a specific class of polymer brush coatings [5] was done for a sliding system that involves ‘silicon skin L7350’: a silicon rubber used by FIFA for the determination of skin / surface friction in combination with artificial grass [6]. Friction experiments were done using a reciprocating pin-on-plate test setup with polymer coated glass plates and flat silicon rubber test pieces. Series of experiments were done focusing on the operational conditions and focusing on the effect of water. Results for the combinations tested at room conditions showed a coefficient of friction values above 1, for most systems. The use of water changed this for the two layers that are able to capture water in their structure. Effective hydration lubrication [2] was able to reduce friction to a coefficient of friction values below 0.01. The results are currently used to further develop ‘low friction’ products for sliding interactions with human skin, e.g. artificial grass and possibly medical textiles