Imperfect Crystals of Poly(butylene succinate) Formed at High Supercooling of the Melt

Abstract Prior work revealed distinct differences in the X‐ray diffraction patterns of poly(butylene succinate) (PBS) melt‐crystallized at different temperatures, regarding the number, width, and position of diffraction peaks, detected in isotropic samples. To further evaluate whether the observed differences are caused by a change of the unit cell, or are solely due to different crystal sizes and perfection, X‐ray fiber patterns of solid‐state oriented PBS are acquired and analyzed. The data reveal that PBS crystallized at high supercooling of the melt at 20 °C contains crystals with enlarged dimensions of the monoclinic unit cell in the cross‐chain direction, compared to PBS crystals initially grown at 20 °C and subsequently reorganized at elevated temperature at 100 °C. High‐temperature reorganized crystals exhibit a unit cell similar to that formed after direct crystallization of the quiescent melt at the same high temperature, with the latter, however, unable to draw for observing X‐ray fiber pattern. The observed changes in the unit cell of PBS when changing the crystallization temperature are discussed in the context of the widely observed crystallization‐temperature‐induced crystal polymorphism in other polymers.