Crystallization Behavior of Poly(Tetramethylene Oxide) Influenced by the Crystallization Condition of Poly(Butylene Succinate) in Their Copolymers

Abstract

The effect of crystallization conditions of poly(butylene succinate) (PBS) component on the crystallization of poly(tetramethylene oxide) (PTMO) component in their segment block copolymer, with a higher PTMO content (PTMO mass fraction is 67%), was investigated by DSC and temperature-dependent FTIR. It is found that the isothermal crystallization time (tIC) of PBS has an effect on the crystallization behavior of PTMO component. Perturbation correlation move-window two-dimensional (PCMW2D) correlation analysis and generalized 2D correlation analysis (2DIR) were performed to explore the origin of this phenomenon. The PCMW2D and 2DIR results show that the correlation intensity peak observed at around 20 °C for PTMO is due to the PTMO chains movements forced by the PBS chains folded movements. If tIC of PBS at temperature of 20 °C is prolonged, more PTMO components are incorporated in the region between PBS lamellae and the peak at -7.6 °C (belonging to less-constricted PTMO chains) changes smaller and even disappears, while the peak at -16.3 °C belonging to more-constricted PTMO chains gets bigger. A crystallization model was also established in this study. The results of tensile testing showed that tensile strength slightly increased and elongation at break decreased with increasing heat treatment time at 40 °C.