Effect of spinning process on structural change in PAN/SWNT fiber

Abstract

As smart application has been developed, electrically conductive polymer nanocomposites with a shape of fiber have been spotlighted. Because of the challenges in controlling micro structure in fiber, electrically conductive fiber has been investigated including manufacturing process. By use of single wall nanotube (SWNT), electrical properties are granted for insulating polymer like polyacrylonitrile (PAN) which has strong interaction with SWNT [1, 2]. In order to manufacture the PAN/SWNT fiber, spinning process is essential process and it controls the micro structure of PAN/SWNT fiber. Spinning process is composed of 4 steps largely including coagulation, washing, drawing and winding steps. Polymer nanocomposite solution is coagulated in coagulation bath with mixture of solvent and non-solvent and diffusion of solvent and non-solvent molecules is performed in the process. Following the coagulation step, through additional coagulation and washing stages, residual solvent molecules diffuses out from the spun solution. In fiber formation steps including coagulation and washing steps, fast co-diffusion between coagulant and washing baths and polymer nanocomposite solution makes void structure in fiber. In this reason, proper diffusion rate is important for fiber formation steps. For better properties obtained from molecular orientation, drawing process is conducted. Through drawing process, molecular orientation can be improved and it leads to enhancement of properties of fiber. Before being taken-up, heat-setting process is carried out for collapsing void structure in fiber through controlling molecular segment above glass transition temperature called Tg. Manufacturing process leads to the change in electrical and mechanical properties resulted from structure such as void distribution and molecular orientation. In this study, wet-spinning was carried out and PAN/SWNT fiber which was taken with every step was investigated. Then, relationship between structure and properties were analyzed.