The kinetics of poly(butylene succinate) synthesis and the influence of molar mass on its thermal properties

The synthesis of poly(butylene succinate) (PBS) of M_w ranging from 4000 to 180,000 g mol^?1 is realized with molar ratios [COOH]₀/[OH]₀ of 1 and 0.98, and varying amounts of titanium (IV) tetrabutoxide (TBT) catalyst. Polycondensation kinetics are followed by chemical titration of carboxylic groups, and the kinetic rate constants of self‐catalyzed and external‐catalyzed reactions are calculated. The synthesis of PBS with high molar mass follows the classical Flory theory. The effect of molar mass on PBS thermal properties is also studied. A faster crystallization rate and a higher temperature of crystallization are observed, for very high molar masses. This behavior could be due to a memory effect of the polymer. Complex melting behavior of PBS is induced by a continuous reorganization of the crystalline phase, as observed by MTDSC. DSC measurements also reveal that the crystallinity—and so the amorphous phase—is limited to about 35% when the molar mass M_n is higher than 40,000 g mol^?1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40639.