Development of Thermally Stable Polybenzimidazole (PBI) Fiber
Final rept. 8 Jun 1970-16 Nov 1971
DYNATECH R/D CO CAMBRIDGE MA
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Textiles composed of polybenzimidazole PBI fibers combine superior qualities of non-flammability and comfort with functional utility. A further improvement desired in the qualities of PBI fabric is reduction of its tendency to shrink when exposed to flame and high temperature. The work reported was undertaken to develop a treatment for PBI which stabilizes it with respect to thermal shrinkage. Chemical treatment of PBI fiber or fabric which introduces chemical bonds between the basic polymer chains of PBI was found to stabilize PBI against thermal shrinkage. Among such treating agents examined a treatment involving immersion of PBI in a liquid mixture of 5 chlorosulfonic acid in phosphorous oxychloride followed by heating and neutralization was found to be satisfactory. Fabric so treated is resistant to thermal shrinkage yet unchanged in strength and nonflammability. The treatment is stable to laundering. A pilot processing line for treating PBI tow was constructed and is discussed.
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