| Summary: | Nitrile rubber (NBR) vulcanizates were prepared by coordination crosslinking of cuprous chloride (CuCl), copper acetate (C4H6CuO4), copper sulfate (CuSO4), and copper chloride (CuCl2). The effects of different copper salts on the curing characteristics, mechanical properties, crosslinking density, and Mullins effect under compression mode of the vulcanizate were investigated. The results showed that a three-dimensional network structure with copper salt as the crosslinking point was formed in the coordination reaction of NBR. Compared to CuCl/NBR, C4H6CuO4/NBR, and CuSO4/NBR, CuCl2/NBR vulcanizates had the highest crosslinking density. During the uniaxial cyclic compression, various copper ion coordination cross-linked NBR vulcanizates caused significant Mullins effects, and the Mullins effect significantly weakened with the increasing crosslinking density of the vulcanizate. At the same strain, the maximum compressive stress of the vulcanizate decreased with the increasing number of loadings and unloads, but the instantaneous residual strain increased with the increasing strain and number of loadings and unloads.
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