Ahm. Schotman et al., STUDIES ON A NEW ANTIREVERSION AGENT FOR SULFUR VULCANIZATION OF DIENE RUBBERS, Rubber chemistry and technology, 69(5), 1996, pp. 727-741
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.