Relationship between Laboratory Abrasion Tests and Service Performance

Abstract

Abstract In development work on GR-S commercial recapping compounds originated in 1943 by the Directorate of Mechanical Engineering, Department of National Defence, Ottawa, Canada, in which an attempt was made to correlate road performance with physical properties as determined in the laboratory, it was found that no relationship whatever existed between the results of road tests carried out under the supervision of that directorate and standard laboratory abrasion resistance tests carried out in the Canadian National Research Council Rubber Laboratory at Ottawa. In the laboratory test the sandpaper in the abrasion machine became coated with a smear of tacky viscous material which the air jet was unable to remove. Under these conditions the rubber tends to slide over the sandpaper surface, with relatively little actual abrasion of the rubber. The effect remains even after a considerable overcure of the sample. It was felt that the removal of the tacky viscous material from vulcanized GR-S by extraction might give more reliable abrasion resistance results, inasmuch as, on the road, rubber is constantly coming in contact with a new surface and such viscous material is thus being continually removed as it migrates to the surface of the rubber. From this point of view, then, the tread surface while being abraded on the road may be looked upon as extracted rubber and may be considered as conforming closely to the extracted laboratory specimen.