Unique orientation textures formed in miscible blends of poly(vinylidene fluoride) and poly [(R)-3-hydroxybutyrate]
Unique orientation textures formed in miscible blends of poly(vinylidene fluoride) and poly [(R)-3-hydroxybutyrate]
复制标题
DOI：
10.1016/j.polymer.2006.03.066
复制
发表时间：
2006-05-03
期刊：
影响因子：
4.6
通讯作者：
Kaito, A
中科院分区：
文献类型：
--
作者：
Kaito, A
研究了不同组成的聚偏氟乙烯（PVDF）与聚[(R)-3-羟基丁酸酯]（PHB）在共混体系中的定向结晶。采用溶液浇铸和冰水熔淬法制备了PVDF/PHB共混膜。利用手动拉伸装置，在0℃的冰水中单轴拉伸熔融淬火膜，制备了共混物的定向膜。为了使PHB在取向状态下结晶，对取向共混膜进行了固定长度的热处理。利用广角x射线衍射（WAXD）和小角x射线散射（SAXS）分别研究了样品的晶体取向和片层织构。SAXS测量结果表明，相当数量的PHB分子链被排除在PVDF的层状堆叠中，并存在于共混物取向膜的纤维间区。PHB在纤维间区的冷结晶导致PHB晶体的取向，晶体取向的类型取决于共混物的组成。对于PVDF/PHB = 4/6-7/3共混体系，PHB晶体的a轴高度定向平行于拉伸方向，PHB晶体的c轴（分子链轴）垂直于拉伸方向，即与PVDF晶体的链轴正交。认为a轴取向是由纤维间纳米畴中晶体生长的限制引起的。而对于PVDF/PHB = 2/8-3/7共混体系，PHB的晶体c轴主要向拉伸方向取向，表明PHB的应力分子链在保持分子取向的情况下结晶。(c) 2006 Elsevier Ltd.版权所有。
The oriented crystallization of poly[(R)-3-hydroxybutyrate] (PHB) in the miscible blends with poly(vinylidene fluoride) (PVDF) was investigated with various compositions. The PVDF/PHB blend films were prepared by solution casting and subsequent melt-quenching in ice water. Oriented films of the blends were prepared by uniaxially stretching the melt-quenched film at 0 degrees C in ice water using a hand-operated stretching apparatus. The oriented blend films were heat-treated at a fixed length in order to crystallize PHB in the oriented state. The crystal orientation and the lamellar textures of the obtained samples were studied with wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS), respectively. The SAXS measurements showed that a considerable amount of molecular chains of PHB are excluded from the lamellar stacks of PVDF and exist in the interfibrillar regions in the oriented films of the blends. The cold crystallization of PHB in the interfibrillar region results in the orientation of PHB crystals, and the type of crystal orientation depends upon the composition of the blends. For the PVDF/PHB = 4/6-7/3 blends, the crystal a-axis of PHB is highly oriented parallel to the drawing direction and the crystal c-axis (molecular chain axis) in PHB crystals is perpendicular to the drawing direction, i.e. orthogonal to the chain axis of the crystals of PVDF. It is considered that the a-axis orientation is induced by the confinement of crystal growth in the interfibrillar nano-domains. For the PVDF/PHB = 2/8-3/7 blends, however, the crystal c-axis of PHB is primarily oriented in the drawing direction, suggesting that the stressed molecular chains of PHB are crystallized with the molecular orientation retained. (c) 2006 Elsevier Ltd. All rights reserved.