Single Crystalline Morphology and Lamellar Assembly in Thin Films of Poly(1,6-hexamethylene adipate)/Poly(vinyl methyl ether) Blend

Content Provider	Semantic Scholar
Author	Hsieh, Ya-Ting Woo, Ming-Ko
Copyright Year	2013
Abstract	The detail lamellar arrangements and the crystalline structures of melt-crystallized poly(1,6-hexamethylene adipate) (PHA) in PHA/poly(vinyl methyl ether) (PVME) 80/20 blend under ultrathin film (~200 nm) and thin film (2-3 m) states were studied by means of polarized optical microscopy (POM), atomic force microscopy (AFM), electron diffraction (ED) and X-ray diffraction (WAXD). For the ultrathin film blend samples, low birefringence spherulitic morphology with a non-straight spherulitic boundary and leaf-like morphology were observed at low crystallization temperature (Tc = 38 o C) and high Tc (Tc = 46 o C), respectively. ED patterns suggested that these two morphologies were all composed by flat-on orthorhombic PHA single crystals, but the crystals became more extended along their [100] direction by increasing the Tc. For the thin film blend samples, a clear optical birefringence and morphology reversion at Tc = 38 o C (negative-type Maltese-cross spherulities) and 46 o C (positive-type petal-like spherulities) was found. The mechanisms of these two types morphologies with their optical birefringence signs were also probed in this study. PHA/PVME 80/20 blend samples in thin film state were also isothermally held at these two temperatures (38 and 46 o C) for several cycles to induce thermo-cycle bands on spherulites. Thermocycle-induced bands with alternating birefringence-color concentric rings in spherulites on a naturally ringless polymer PHA were used to prove that alternating ring bands can be packed with mechanisms different from the conventionally thought continuous spiral of a continuous lamella. The lamellar assembly in transition regions (from one band to the other band) was also investigated in detail by using AFM.
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Language	English
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Content Type	Text
Resource Type	Article