An investigation of the effects of polymer structure upon the dissociation temperature of macromolecular-blocked isocyanates.

摘要

The effect of polymer structure upon the dissociation temperatures, rates, and mechanism of polymeric blocked isocyanates is discussed. Specifically, a blocked isocyanate monomer, based on the reaction of isocyanatoethyl methacrylate and pentachlorophenol, was incorporated into acrylic co- and terpolymers were synthesized and characterized. The resulting co- and terpolymers possessed a dissociation temperature range in excess of 150{dollar}spcirc{dollar}C and shelf lives between 2 and 13 months.; Dissociation temperatures of the monomer and polymers were determined through the use of differential scanning calorimetry and hydrogen bonding ability of the materials was elucidated via fourier transform spectroscopy. A relationship among the dissociation temperature, T{dollar}rm sb{lcub}g{rcub}{dollar}, shelf life, and hydrogen bonding ability of each of the polymers was established. Acrylic co- and terpolymers possessing relatively low T{dollar}rm sb{lcub}g{rcub}{dollar}s exhibited low dissociation temperatures (ambient temperature to 60{dollar}spcirc{dollar}C), significant hydrogen bonding, and abbreviated shelf lives (2-4 months). On the other hand, acrylic co- and terpolymers possessing relatively high T{dollar}rm sb{lcub}g{rcub}{dollar}s exhibit elevated curing temperatures (165-185{dollar}spcirc{dollar}C), decreased hydrogen bonding, and shelf lives of 13 months.