CHARACTERIZATION OF CIS-1,4-POLYBUTADIENE RAW RUBBER

A Ni-catalyst/aliphatic hydrocarbon solution polymerization system was developed forthe production of cis-1, 4-polybutadiene. Ten kinds of methods were used for the characteri-zation of this domestic raw rubber so as to compare it with the samples made abroad. All thedomestic samples have a broader molecular weight distribution in the presence of rather highfractions, which affects to some extent the viscoelastic properties, such as Δ (ML～t), stress-strain curve and stress-relaxation rate. The effect of gel and branching on the processingbehavior is rather strong. When the gel content is less than 1%, the branching moleculesplay the main role in affecting the viscoelastic properties and processing behavior of thepolymer. Such evidence was also observed in the imported polybutadiene samples which werepolymerized by Ni, Co and Ti catalysts. Our results show that it is not sufficient to useML only in evaluating the processing behavior of cis-1, 4-polybutadiene raw rubber. Thesedetermination of Δ(ML～t) values and analyses of the stress-strain curves, especially theyield strength and 300% tensile strength, are recommended as methods for evaluating thequality and pre-estimating the processing behavior of cis-1, 4-polybutadiene rubber.