Two crystal populations with different melting/reorganization kinetics of isothermally crystallized polyamide 6. Issue 20 (12th July 2016)

• Record Type: Journal Article
• Authors: Furushima, Yoshitomo; Nakada, Masaru; Ishikiriyama, Kazuhiko; Toda, Akihiko; Androsch, Rene; Zhuravlev, Evgeny; Schick, Christoph
• Is Part Of: Journal of polymer science. Volume 54:Issue 20(2016)
• Page Start: 2126
• Page End: 2138
• Publication Date: 2016-07-12
• Subjects: crystallization -- differential scanning calorimetry (DSC) -- fast scanning calorimetry -- melting kinetics -- melting point -- polyamides -- small‐angle X‐ray scattering (SAXS) -- superheating -- zero‐entropy‐production melting; 547
• DOI: 10.1002/polb.24123
• Languages: English
• ISSNs: 0887-6266

Abstract

ABSTRACT: Differential scanning calorimetry and fast scanning chip calorimetry heating experiments were carried out in a wide range of rates of temperature change from 0.2 to 60, 000 K s −1 for isothermally crystallized polyamide 6. Multiple melting peaks were observed. With increasing heating rate, the highest‐temperature endotherm shifts toward lower temperatures and finally disappears due to suppression of the reorganization. The critical heating rate to suppress reorganization was 15–50 times higher than the critical cooling rate to cause complete vitrification. On heating at rates higher than the critical heating rate to suppress reorganization, there were observed two melting processes of different kinetics. Four possible assignments were considered regarding the two crystal populations. These are (i) crystals grown during primary and secondary crystallization, (ii) crystals grown in the bulk and nucleated at the surface/substrate, (iii) crystals, which are subjected to different local stress originating from heterogeneities in interlamellar regions, and (iv) the crystal/mesophase polymorphism. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2016, 54, 2126–2138 Abstract : The multiple melting behaviors of isothermally crystallized polyamide 6 samples were investigated using differential scanning calorimetry and fast scanning chip calorimetry in a wide range of rates of temperature change from 0.2 to 60, 000 K s −1 . The analysis of heating‐rate dependence of melting temperatures reveals that two different crystal populations with different melting kinetics exist in isothermally crystallized sample. In addition, the relation between melting temperatures and crystallization temperature was discussed.