Rheokinetics of ring-opening metathesis polymerization of norbornene-based monomers intended for self-healing applications

Constant shear rate rheokinetics was used to evaluate the polymerization of four norbornene-based monomer systems as candidate healing agents in self-healing composites: encto-dicyclopentadiene (endo-DCPD), exo-DCPD, 5-ethylidene-2-norbornene (ENB), and a 1:1 volume mixture of endb-DCPD:ENB. The ruthenium catalyst induced ring-opening metathesis polymerization of the healing agent candidates were measured experimentally under isothermal conditions while the influences of several different variables were considered (e.g., test temperature, catalyst concentration, catalyst form). Analyzing the increase in viscosity during the polymerization, comparisons of the reaction kinetics of the different monomers were quantified by defining two parameters, t_t, and Δt, which correspond to the polymerization initiation and propagation rates respectively. Generally, ENB shows the fastest polymerization kinetics, and endo-DCPD the slowest