Effects of KBrO3 on Chemical, Aggregation and Morphological Structure of Polyacrylonitrile (PAN) Precursor Fibers

Microstructural Evolution during Dry-Jet Wet Spinning Postprocessing from Coagulation Bath Fiber to High-Performance Polyacrylonitrile Precursor Fiber

“…Figure a shows the DSC curves of PAN fibers at each of the five stages (P1–P5) under a nitrogen atmosphere. A peak of heat release existed within the range of 250–300 °C, which was caused by the internal molecular chain of the fiber undergoing nitrile group cyclization to form a more heat-resistant trapezoidal structure during the heating process (Figure b) . During the steam stretching and heat setting stages, the onset temperature of the P5 exothermic peak was significantly delayed, and the peak narrowed owing to the increased activation energy of cyclization.…”

“…A peak of heat release existed within the range of 250−300 °C, which was caused by the internal molecular chain of the fiber undergoing nitrile group cyclization to form a more heatresistant trapezoidal structure during the heating process (Figure 2b). 34 During the steam stretching and heat setting stages, the onset temperature of the P5 exothermic peak was significantly delayed, and the peak narrowed owing to the increased activation energy of cyclization. This change may be attributed to the more regular and ordered arrangement of PAN molecular chains and the more perfect crystal structure at the P5 stage, reflecting the criticality and importance of the steam drawing and heat setting stages in the processing and preparation of PAN fibers.…”

Terpolymers of acrylonitrile, methyl acrylate, and 2‐acrylamido‐2‐methylpropane sulfonic acid for carbon fiber precursor: Effect of comonomers on the thermal stabilization of polyacrylonitrile copolymers

“…During this process, PAN filaments undergo cyclization, dehydrogenation, oxidation, and isomerization reactions. [11][12][13][14] And, the physical and chemical structure of the filaments undergoes many complex changes. Meanwhile, the PAN molecular chain gradually changes from a linear structure to a trapezoidal ring structure, a structure that allows the fibers to withstand higher temperature carbonization treatments.…”