MgO and ZnO as reinforcing fillers in cured polychloroprene rubber

Polychloroprene rubber (CR) is generally cured in a manner different from that of other diene rubbers. Compounding formulations based on metal oxides have been used satisfactorily for the crosslinking of CR, especially magnesium oxide (MgO) and zinc oxide (ZnO) at loadings of 4 and 5 phr, respectively. In this work, the total loading of MgO and ZnO was varied while the MgO : ZnO loading ratio of 4 : 5 (equivalent to MgO and ZnO volume fractions of 0.013 and 0.009, respectively) that usually used with CR was kept constant. Cure and mechanical properties of CR compounds and cured specimens were investigated. The obtained results could resolve the separate increments in hardness, tensile strength, abrasion resistance, and modulus associated with the increases in crosslink density and total loading of metal oxides. Furthermore, poor compression set and increased heat build-up of cured CR specimens, particularly at high total loading of metal oxides, were believed to be the result of a post-curing effect and of molecular restriction by the increased crosslink density, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013