Calorimetric Investigation of the Structural Development of
Wet-Spun Polyacrylonitrile Fibers
Shahram Arbab, Parviz Noorpanah
Introduction
Acrylic fibers are the most important precursor of high strength carbon fibers [1]. It has been shown that the properties of carbon fibers strongly depend on the structure of the initial precursor [2,3]. Hence, understanding the mechanisms of structure development of acrylic fiber during spinning is a key to design better precursors and improve mechanical properties of the resulting carbon fiber [1-3]. Acrylic fibers are usually produced by wet spinning which is an interesting example of immersion precipitation [1,4]. During this process voids are formed through a nucleation and growth mechanism. The size and connectivity of the voids has a crucial role in determining the final mechanical properties of the fiber [5]. Macrovoids are believed to reduce fiber strength and modulus [5]. Different methods have been applied to investigate the porous structure of acrylic fibers. In recent years, there has been an increasing interest in Differential Calorimetry as a strong method to study the nanostructure of porous materials such as membranes. Thismethod is known as Thermoporometry in the literature. In this work, we applied this method to investigate structural development of wet-spun acrylic fibers.
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