At what temperature does polyacrylonitrile undergo thermal degradation?

Understanding the Thermal Degradation of Polyacrylonitrile

Polyacrylonitrile (PAN), a widely used synthetic polymer foundational to carbon fiber production, undergoes significant chemical changes when exposed to elevated heat. When heated, PAN does not simply melt; instead, it triggers complex exothermic reactions that alter its structure entirely.

Research shows that the thermal degradation of polyacrylonitrile typically takes place within the temperature range of 280–450°C. During this window, the material experiences profound intramolecular cyclization, dehydrogenation, and cross-linking.

As the temperature climbs through this critical bracket, the polymer chains begin to cyclize, transforming the flexible white or transparent polymer into a rigid, ladder-like structure. This structural transformation is a crucial step in stabilizing the fiber before it is carbonized at even higher temperatures to produce high-strength carbon materials used in aerospace, sports equipment, and engineering fields. Managing this thermal window precisely prevents uncontrolled degradation and ensures the final carbon product maintains its structural integrity.