Preparation and properties of novel green poly(ether–ester urethane)s insulating coatings based on polyols derived from glycolyzed PET, castor oil, and adipic acid and blocked isocyanate

To utilize renewable resource raw materials as well as trying to recycle polymeric materials, three new polyols (PEE1‐3) were prepared from trasesterification reaction of postconsumer poly(ethylene terephtalate) (PET), different molecular weights of poly(ethylene glycol) (PEG), and glycerine. The intermediate hydroxyl‐terminated compounds were chain extended via esterification reaction with adipic acid (AA), and the products were reacted with castor oil (CO). These polyols were cured by blocked isocyanate (BIC) made from trimethylol propane, toluene diisocyanate, and N‐methyl aniline. All of starting materials and final films were characterized by conventional methods. Curing condition was optimized via gel content measurements. Crosslink density of samples was determined via equilibrium swelling method, using Flory–Rehner equations. Effects of structural parameters on physical, electrical, mechanical, and dynamic mechanical (DMTA) properties of the polyurethane coatings were investigated. Comparison of results with commercially available product shows that the prepared green coatings have environmental benefits as well as high performance for metal insulator coatings too.