Shape Memory Performance of Thermoplastic Polyvinylidene Fluoride/Acrylic Copolymer Blends Physically Cross-Linked by Tiny Crystals
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- 作者：Jichun You ; Hui Fu ; Wenyong Dong ; Liping Zhao ; Xiaojun Cao ; Yongjin Li
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2012
- 出版时间：September 26, 2012
- 年：2012
- 卷：4
- 期：9
- 页码：4825-4831
- 全文大小：480K
- 年卷期：v.4,no.9(September 26, 2012)
- ISSN：1944-8252
文摘
Polyvinylidene fluoride (PVDF)/acrylic copolymer (ACP) blends are a typical miscible crystalline/amorphous system over the whole composition range. Our previous investigation indicated that blend samples with controlled component ratios and crystallization conditions exhibit good shape memory properties (J. Phys. Chem. B2012, 116, 1256鈥?264). In this work, we systematically investigated the cold crystallization temperature effects on the crystal morphologies and the shape memory properties for the 50/50 blend. It was found that the quenched blend is an amorphous material with a low glass transition temperature. Annealing at temperatures above Tg of the blend induces crystallization of PVDF from the miscible amorphous PVDF/ACP phase, leading to an increased glass transition temperature of the blend. High annealing temperature results in large PVDF spherulites, while low annealing temperature produces tiny crystals in the blend. Furthermore, tiny crystals serve as the physical cross-link points and the amorphous regions among them act as the reversible phase for the blend materials during the mechanical deformations. Therefore, the PVDF/ACP blends with tiny crystals show not only high shape fixity but also excellent recovery ratios.