| 摘要 |
Polymers containing at least 80 per cent of acrylonitrile are dissolved in aqueous nitric acid of 46 to 68 per cent by weight concentration at temperatures below 80 DEG C., and the solutions produced are processed at temperatures up to 180 DEG C. into shaped structures such as films and fibres. In a modification the acrylonitrile polymer is dissolved in a mixture containing 15 to 95 per cent of nitric acid and 85 to 5 per cent of nitromethane. Polymers of acrylonitrile specified are polyacrylonitrile and copolymers with vinyl pyrrole, vinyl chloride, vinyl acetate, styrene, butadiene, methacrylonitrile, and acrylic and methacrylic acids. The process is preferably applied to polymers having a molecular weight between 10,000 and 90,000 which have been prepared with the assistance of organic catalysts. The methods by which the solutions are prepared may be varied according to the temperatures and concentrations of nitric acid employed; when using a mixture of nitric acid and nitromethane the polymer is preferably first suspended in nitromethane and the suspension converted to a solution by the addition of nitric acid. Reference has been directed by the Comptroller to Specification 701,652. |
