Effect of multi-step annealing above the glass transition temperature on the crystallization and melting kinetics of semicrystalline polymers. (12th August 2020)

• Record Type: Journal Article
• Authors: Furushima, Yoshitomo; Toda, Akihiko; Schick, Christoph
• Is Part Of: Polymer. Volume 202(2020)
• Publication Date: 2020-08-12
• Subjects: Fast scanning calorimetry -- Crystallization -- Thermal history; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2020.122712
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Fast scanning calorimetry (FSC) measurements were carried out for multi-step, isothermal, crystallized poly (butylene terephthalate) to quantify the effect of single-step to triple-step annealing above T g (40 °C interval below the previous annealing temperature) on the crystallization/melting kinetics. In the case of double-step annealing, two endothermic peaks were observed on the FSC curves due to the melting of the crystal formed during the 1st step (base crystal; BC) and 2nd step (thermal history crystal; THC). The crystallization rate of the THC decreased due to the spatial restriction of the pre-existing BC. The melting kinetics of the THC were not affected by the time of 1st step crystallization. If the sample was re-heated to the 1st step temperature ( T c1 ) after multiple annealing, the thermal history of the previous annealing was completely erased. Moreover, in the re-annealing process at T c1, secondary crystallization showed the same behavior as that expected from the result of single-step annealing. Graphical abstract: Image 1 Highlights: Kinetics of multi-step crystallization and melting were quantified by calorimetry. The memory of low temperature crystallization is erased by re-heating. Melting point of thermal history crystals is not affected by the base crystal. Poly(buthylene terephthalate) and isotactic polypropylene show the same trend.