Preparation and aggregate structure of polyacrylonitrile and microcrystalline cellulose hygroscopic thermal composite fibers

Abstract Hygroscopic thermal fibers are a kind of functional material that makes use of moisture to generate heat for fabrics. In this work, composite fibers of polyacrylonitrile (PAN) and microcrystalline cellulose (MCC) with various compositions were prepared using a solution spinning method. Besides the promotion of mechanical properties of PAN by addition of cellulose reported in previous research, this study focused on the hygroscopic thermal property of blends and spun fibers of PAN and cellulose. The content of MCC in the composite fibers has a significant effect on the hygroscopic thermal property. At a temperature of 17 °C and humidity of 90%, the maximum temperature increase of composite fibers could reach 4.9 °C. The composite fibers exhibited an obvious temperature response of on–off humidity circulation during testing. The breaking strength of the composite fibers was higher than 100 MPa. The influence of addition of cellulose on morphology, especially on the crystallinity and lateral size of PAN microfibrils, and the relationship between the morphology and hygroscopic thermal property were investigated by means of wide‐angle X‐ray diffraction and small‐angle X‐ray scattering in terms of experiment and theory. A smaller lateral size of microfibril led to a better hydroscopic thermal property. The composite fibers were expected to be used in temperature regulation clothing. © 2022 Society of Industrial Chemistry.