Unique Orientation Textures Induced by Confined Crystal Growth of Poly(vinylidene fluoride) in Oriented Blends with Polyamide 6

✍ Scribed by Akira Kaito; Yuko Iwakura; Yongjin Li; Kazuo Nakayama; Hiroshi Shimizu

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 645 KB
• Volume: 208
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200600508

✦ Synopsis

Abstract

Unique orientation textures have been induced by the confined crystal growth of PVDF in drawn films of PVDF/PA6 blends. Oriented films of PVDF/PA6 blends were prepared by uniaxially drawing melt‐mixed blends. The drawn films with fixed lengths were heat‐treated at 180 °C for 3 minutes to melt the PVDF component, followed by non‐isothermal crystallization of PVDF at a cooling rate of 0.5 °C · min^−1^. The crystal orientation was studied by WAXD. When PVDF was melted and recrystallized in the drawn films of the PVDF/PA6 = 50/50 blend at a slow cooling rate, the crystal __b‐__axis of the α‐crystalline form of PVDF was oriented in the drawing direction, forming orthogonal orientation textures. SEM showed that stretched domains of PVDF with diameters of 0.2–0.5 µm were dispersed in the PA6 phase in the drawn films of the PVDF/PA6 = 50/50 blend. Spatial confinement of the crystal growth resulted in the alignment of the crystal __b‐__axis along the long axis of the domains, because PVDF is crystallized in thin cylindrical domains. The orientation behavior is different from the oriented crystallization of PVDF/PA11 (Y. Li, A. Kaito, Macromol. Rapid Commun. 2003, 24, 255), in which transcrystallization from the interface causes the __a‐__axis orientation to be in the drawing direction. It is thought that the domain size influenced the mechanism of oriented crystallization and the resultant crystal orientation.

magnified image