Process for the production of stabilized acrylic fibers which are particularly suited for thermal conversion to carbon fibers

An improved process for the relatively rapid thermal stabilization of a multifilamentary acrylic fibrous material in the substantial absence of filament coalescence comprising:

• (a) contacting said acrylic fibrous material with an approximately 4 to 6 percent by weight aqueous solution of hydroxylamine having a pH of approximately 6 to 8 provided at a temperature of approximately 95.degree. to 130.degree. C. for approximately 2 to 6 minutes,
• (b) washing said fibrous material,
• (c) contacting said resulting fibrous material with an approximately 0.5 to 2 percent by weight aqueous solution of an oxidizing agent selected from the group consisting of ammonium permanganate, calcium permanganate, magnesium permanganate, and mixtures thereof, provided at a temperature of approximately 80.degree. to 120.degree. C. for approximately 1 to 4 minutes,
• (d) washing said fibrous material, and
• (e) heating said resulting fibrous material in a gaseous oxygen-containing atmosphere until a thermally stabilized acrylic fibrous material is formed which is capable of undergoing carbonization and is non-burning when subjected to an ordinary match flame.

An improved process for the relatively rapid thermal stabilization of a multifilamentary acrylic fibrous material in the substantial absence of filament coalescence comprising:

• (a) contacting said acrylic fibrous material with an approximately 5 percent by weight aqueous solution of hydroxylamine having a pH of approximately 7 provided at a temperature of approximately 95.degree. to 100.degree. C. for approximaterly 2 to 6 minutes,
• (b) washing said fibrous material,
• (c) contacting said resulting fibrous material with an approximately 1.5 percent by weight aqueous solution of ammonium permanganate at a temperature of approximately 95.degree. to 100.degree. C. for approximately 1 to 4 minutes,
• (d) washing said fibrous material, and
• (e) heating said resulting fibrous material in a gaseous oxygen-containing atmosphere at a temperature of approximately 240.degree. to 310.degree. C. until a thermally stabilized acrylic fibrous material is formed which is capable of undergoing carbonization and is non-burning when subjected to an ordinary match flame.