Characterization, Crystallization Kinetics, and Melting Behavior of Poly(ethylene succinate) Copolyester Containing 7 mol % Butylene Succinate

The copolyester was synthesized and characterized as having 92.7 mol % ethylene succinate units and 7.3 mol % butylene succinate (BS) units in a random sequence, as determined by the use of nuclear magnetic resonance. Isothermal crystallization kinetics of this copolyester was examined in the temperature range (T-c) from 30 to 80 degrees C with the use of differential scanning calorimetry (DSC). The melting behavior after isothermal crystallization was studied with DSC by varying the T-c the heating rate, and the crystallization time. The complex melting behavior involves both mechanisms of various lamellar crystals and melting-recrystallization-remelting. As the T-c increases, the contribution of recrystallization gradually decreases and finally disappears. The Hoffman-Weeks linear plot yielded an equilibrium melting temperature of 111.1 degrees C, which is 1.6 degrees C less than that of poly(ethylene succinate) (PES). The kinetic analysis of the spherulitic growth rates (G) indicated that a regime II -> III transition occurred at similar to 59 degrees C (T-II -> III), which is similar to 11 degrees C less than that of PES. The overall crystallization rate, T-II -> III and G indicate that the random incorporation of only 7.3 mol % BS units into PES significantly inhibits the crystallization rate of PES. Finally, the morphology of melt-crystallized samples was examined using polarized light microscopy and scanning electron microscopy. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 876-886, 2009