Liquid (melt) heat capacities and heats of vaporization of oligomers of poly(hexamethylene sebacate)

Abstract

AbstractThe liquid heat capacities and heats of vaporization of three linear esters of poly(hexamethylene sebacate) with hexylcapped end groups (M(mol. wt.) = 370, 655, and 939) have been determined. The heats of vaporization of the oligomers measured at a mean temperature were corrected to 323.15 to 523.15°K by use of the experimental liquid (melt) heat capacities and the calculated gas heat capacities. The corrected heats of vaporization were fitted to the equation ΔHv = S(T)Mα + I(T), where the temperature dependence of the slope and intercept are represented, respectively, as S(T) = ClnT + Ko and I(T) = a T + bo, and α is an exponent. The results indicate (at corresponding molecular weights and constant temperature) that the ratio of the liquid heat capacities of the oligomer ester and the n‐alkane, and similarly the ratio of the heats of vaporization, depend on the number of carboxyl groups in the oligomer ester chain.