| 摘要 |
Threads or fibres of polyacrylonitrile are bleached by treatment with an aqueous solution of a permanganic salt, e.g. potassium permanganate, at a pH less than and temperatures between 20 DEG C. and 100 DEG C., followed by washing with an aqueous solution of a substance capable of reducing the combined manganese to manganous ions, for example, sodium bisulphite. The pH of each solution may be adjusted, e.g. to 2, with sulphuric acid. The threads or fibres may be dried without heating after immersion in each bath. |
