Pyrolysis of polyacrylonitrile

Abstract Polyacrylonitrile of molecular weight 130,000 has been pyrolyzed under nitrogen, between 200° and 320°. The predominant gaseous products are hydrogen cyanide and ammonia; the rates of formation of these have been measured, and at 270° for example, after 300 minutes, only 10% of the available nitrogen is lost. A liquid distillate containing nitriles, amines, and unsaturated groups was also obtained. Using infrared absorption measurements, it was found that the nitrile groups of the polymer disappear as heating progresses, and CN linkages appear. As heating is continued, evidence for aromatization is found. These experimental facts indicate ring formation to be an important reaction; the heat‐stable residues are considered to be mainly fused pyridine systems.