Novel polyurethane insulating coatings based on polyhydroxyl compounds, derived from glycolysed PET and castor oil

To prepare versatile polyurethane material suitable as insulating coatings, novel kinds of polyhydroxy compounds (PHCs) were prepared via transesterification reaction of poly(ethylene terphthalate), different molecular weight of poly(ethylene glycol)s (PEGs), and castor oil. The final networks were prepared via crosslinking of PHCs with a novel blocked isocyanate curing agent (BPI) made from trimethylol propane (TMP), toluene diisocyanate (TDI), and N-methyl aniline (NMA). Polyols and curing agent were characterized by conventional methods and the curing condition was optimized via gel content measurements. Curing kinetic of the polyurethane network formation was investi-gated by differential scanning calorimetric method and the kinetic parameters were derived. Crosslink density of the samples was determined via equilibrium swelling method and by using Flory-Rehner equations. Effects of crosslink density on electrical, physical, mechanical, and dynamic mechanical (DMTA) properties of the polyurethane coatings were investigated. (c) 2005 Wiley Periodicals, Inc.