Effect of heat treatment on the structure and mechanical properties of polyacrylonitrile fibers

Abstract

Abstract Strucure and mechanical properties of untreated and thermally treated (at 110°C and 150°C) drawn polyacrylonitrile (PAN) fiber have been studied through IR spectroscopy, wide angle X‐ray diffraction, and tensile and dynamic mechanical properties measurements. The results are interpreted in terms of the change in the degree of bound nitrile group pairs on heat treatment. The heat treatment at both the temperatures resulted in higher degree of bound nitrile groups (through their dipolar interactions) in the heat‐treated PAN than that of the untreated PAN, as evidenced by IR spectroscopy, X‐ray diffraction, and the mechancal properties. The difference between the results for the two heat‐treatment temperatures are not sufficiently large, although the changes produced by heat treatment at 110°C seems somewhat more prominent than those produced by heat treatment at 150°C.