Rubber Chemistry and Technology · 1996 · 25 citations · 0 references
Natural SciencesChemistryMaterials SciencePolymer ChemistryPolymer EngineeringReaction EngineeringSulfur ChemistrySulfur CompoundsThermosetsConjugated DienesCure TimeVulcanizationVulcanization Kinetics
Abstract The mechanism of biscitraconimides (BCI) as antireversion agents for sulfur vulcanized diene rubber was investigated choosing squalene as a model substrate. Curing of squalene with sulfur in the presence of accelerator, activator and BCI at 170°C gave BCI bridged adducts. The products were identified by spectroscopic methods as being results of a Diels-Alder reaction of BCI (dienophile) with conjugated polyenes that are formed as a result of reversion. The rate at which the sulfur network degrades is comparable to the rate in which BCI adduct is formed. As a result of this, a nearly constant crosslink density is obtained after optimum cure time ( t 90). Based on this concept, the advantage of using 1,3- bis -(citraconimidomethyl) benzene (BCI-MX), a representative of the BCI-class, in NR based compounds is examined.