On the crystal stabilization during two-step isothermal crystallization of poly(butylene terephthalate) examined by fast scanning calorimetry. (16th September 2021)

• Record Type: Journal Article
• Authors: Toda, Akihiko; Furushima, Yoshitomo; Androsch, René; Schick, Christoph
• Is Part Of: Polymer. Volume 230(2021)
• Publication Date: 2021-09-16
• Subjects: Crystal stabilization -- poly(butylene terephthalate) -- Fast scanning calorimetry; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2021.124057
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Crystallization behaviors on two-step isothermal crystallization at T c 1 and T c 2 ( < T c 1 ) were examined by fast scanning calorimetry for poly(butylene terephthalate) in order to identify the dominant process during the secondary stage of crystallization at T c 1 after the completion of spherulitic growth under isothermal condition. From the difference between the melting peaks obtained before and after the low-temperature crystallization step at T c 2, the distinction of the following two processes became realizable: the growth of crystals formed at T c 2 and the stabilization of crystals formed at T c 1 . The dependences on T c 2 and the duration of times Δ t c 1 and Δ t c 2 revealed the following: The formation and growth of new crystals are controlled by thermodynamic driving force determined by supercooling, and hence are suppressed at T c 1 higher than T c 2 . The crystal stabilization is controlled by the mobility of polymer chains, and became more pronounced at T c 1 . Therefore, the dominant process of the secondary crystallization under isothermal condition at T c 1 should be the stabilization of crystals formed in the primary stage and the formation of new crystals will only have a secondary effect. Graphical abstract: Image 1 Highlights: Two-step crystallization, first at T c 1 and then at T c 2 ( < T c 1 ) was examined for PBT. Crystals formed at T c 1 stabilize on additional annealing at T c 1 or T c 2 . Stabilization of crystals formed at T c 1 is more pronounced at higher T c 2 . Annealing at T c 2 yields new crystals, with this process more pronounced at lower T c 2 .