A CRITICAL-REVIEW OF THE STABILIZATION OF POLYACRYLONITRILE

The pre-oxidative stabilisation of polyacrylonitrile (PAN) is a crucial step in the production of PAN-based carbon fibres. Much research has been devoted in the 1950s and 1960s towards elucidating the reactions undergone by PAN during stabilisation. In the past, the mechanism of stabilisation was quite controversial, with much dispute about crosslinking and cyclisation. Now, cyclisation with the formation of six-membered rings seems to have become accepted, though the evidence still remains circumstantial. Alternative interpretations of the changes occurring during stabilisation are also discussed. The possibility of base-induced cyclisation in solution is reviewed along with other pre-treatments for speeding up stabilisation.