The Kinetics of Poly(butylene succinate) Synthesis and the Influence of Molar Mass on Its Thermal Properties

摘要

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).