Thermal characterization and crystallization kinetics of polyester polyols derived from adipic acid and bio-based succinic acid with 1,4-butanediol and 1,6-hexanediol

Crystallization kinetics, thermodynamics, and powder XRD measurements were performed on polyester polyols (PESP) made from succinic acid, SA, or adipic acid, AA, with 1,4-butanediol, BDO, or 1,6-hexanediol, HDO, at 2000 Da M-n. The SA BDO PESP exhibited the greatest crystallization supercooling. The Avrami crystallization kinetics n values are 4 or higher, indicative of sporadic nucleation of spherulitic crystals. At similar crystallization t(1/2), SA BDO K-eq determined from, Delta G(c) is ten times greater and SA HDO is five times greater than AA BDO K-eq. AA BDO and AA HDO have equivalent K-eq at similar t(1/2). Increasing the diol chain length from four carbons to six carbons increases the Delta G(c) temperature dependence for SA PESP, but has little impact on the Delta G(c) temperature dependence of AA PESP. Powder XRD shows that these PESPs contain 35%-40% macrocrystals comprised of nanocrystals with average dimensions of 6-10 nm per side. (C) 2016 Elsevier Ltd. All rights reserved.