Chronological effects of oxygen on the structural transformations of polyacrylonitrile fibers during the rapid thermal stabilization process.

This study investigates the chronological effects of oxygen on the structural transformations of PAN fibers during the rapid thermal stabilization process. In the shorter-time period, PAN fibers undergo a few thermal-driven dehydrogenation reactions alone, while the initiation of both oxidative dehydrogenation and oxygen uptake reactions requires a longer stabilization time. Interestingly, both the amorphous regions and the lateral crystallite sizes increase simultaneously during these periods, resulting in greater exothermic enthalpy.

New insights into the radial structural differences of polyacrylonitrile fibres during thermal stabilization by the synchronous processing adjustment of time and temperature.

In this study, the synchronous effects of time and temperature on the radial structural differences of polyacrylonitrile (PAN) fibres during thermal stabilization were investigated. For each sample to achieve equal densities (∼1.36 g cm), PAN fibres were thermally stabilized for various times between 8-32 min and at corresponding temperatures of 279-252 °C, which was considered to give a synchronous processing adjustment as a time-temperature integral (TTI).

Effects of oxygen on the structural evolution of polyacrylonitrile fibers during rapid thermal treatment.

In this study, the mechanism of stabilizing polyacrylonitrile (PAN) fibers in a short period of time is investigated through probing the effects of oxygen on the structural evolution of PAN under different temperature regimes. It has been found that oxygen has a significant influence on both the chemical and physical structural evolution of PAN fibers, even in a short period of stabilization time, and the influences are dissimilar at different stabilization temperatures. At lower temperatures (below 140 °C), there is no noticeable change in the chemical and physical structures of the PAN fibers.