The influence of wood extractives on paper-to-paper friction

Friction was measured on impregnated filter paper sheets using an apparatus based on the horizontal plane principle. The first static, S1, the third s tatic, S3 and the third kinetic coefficient of friction, K3 were measured. Acid-washed filter paper was used as a model paper. The filter paper sheets were impregnated with 24 different wood extractives in order to study the individual influences of these wood extractives on paper-to-paper friction. The model compounds, which represent major components of wood resin, were different saturated fatty acids and fatty alcohols. unsaturated fatty acids , triglycerides, resin acids. alkanes, sterols and betulin. The model compo unds lowered the friction to different extents. The long chain saturated fa tty acids and fatty alcohols, tristearin and the sterols decreased friction to the lowest values obtained in this study. No dramatic change in paper-t o-paper friction was observed when the filter papers were impregnated with the other wood extractives. It was however found that resin acids also caus ed a slight decrease in paper-to-paper friction, which was contradictory to previous findings. A model to describe the effect of the wood extractives on paper-to-paper friction is proposed.