The cis/trans ratio, which determines the degree of crystallinity of VESTENAMER®, is controlled by the polymerization conditions. In general, a higher concentration of trans double bonds results in a higher crystallinity and thus a higher melting point. The crystallinity is thermally reversible, and the crystallization rate is exceptionally high. This effect can be used to reduce the cold flow of soft compounds, for example, to improve green strength and reduce shrinkage in calendering.
Double bond content
On metathesis polymerization, the double bond of the monomer cyclooctene is preserved so that the resulting transpolyoctenamer contains a double bond at every eighth carbon atom. This is why the vulcanization speed is somewhat lower than for SBR. VESTENAMER® vulcanizes with all crosslinking agents commonly used in rubber curing, such as sulfur, sulfur donors, peroxides and curing resins.