ISOTHERMAL CURING OF AN UNCATALYZED DICYANATE ESTER MONOMER - KINETICS AND MODELING

The isothermal cure of a dicyanate ester monomer has been studied under different atmospheres (air and argon) without any catalyst, by following the evolutions of both glass transition temperature and conversion. Independently of both atmosphere and temperature of cure, there is a unique one-to-one relationship between these two parameters, correctly described by a restated DiBenedetto's equation. The chemical kinetics are satisfactorily modeled with two competing reactions schemes, which are second-order and second-order autocatalyzed, the latter displaying more relative importance under air-curing conditions. Whatever the cure temperature may be, gelation occurs around 0.60 conversion under air, whereas the theoretical x(gel) = 0.50 is experimentally observed under argon. The time-temperature-transformation diagrams have been established. (C) 1993 John Wiley & Sons, Inc.