STUDIES ON A NEW ANTIREVERSION AGENT FOR SULFUR VULCANIZATION OF DIENE RUBBERS

The mechanism of biscitraconimides (BCI) as antireversion agents for s ulfur vulcanized diene rubber was investigated choosing squalene as a model substrate. Curing of squalene with sulfur in the presence of acc elerator, activator and BCI at 170 degrees C gave BCI bridged adducts. The products were identified by spectroscopic methods as being result s of a Diels-Alder reaction of BCI (dienophile) with conjugated polyen es that are formed as a result of reversion. The rate at which the sul fur network degrades is comparable to the rate in which BCI adduct is formed. As a result of this, a nearly constant crosslink density is ob tained after optimum cure time (t90). Based on this concept, the advan tage of using 1,3-bis-(citraconimidomethyl) benzene (BCI-MX), a repres entative of the BCI-class, in NR based compounds is examined.