Mechanical properties and friction of rubber vulcanizates: Aspects of crosslink structure

Vulcanizates of styrene–butadiene rubber (SBR) and carboxylic acrylonitrile–butadiene rubber (XNBR) of different crosslink structures were prepared. The degree of crosslink sulphidity of SBR and the content of ionic crosslinks in the case of XNBR were varied according to curing system applied. The influence of crosslink structure on surface energy, mechanical and dynamic properties as well as friction of rubber vulcanizates was studied. It has been found, that increase of polar crosslinks content results in higher surface energy of the vulcanizates, especially its polar component. Despite increased adhesion, rubber vulcanizeates of higher content of polysulphide crosslink and ionic multiplets or clusters exhibit lower coefficient of friction, due to their ability to stress dissipation. The results obtained create perspectives for tailoring friction of rubber vulcanizates by controlling their crosslink structure.