Process for the oxidation of polyarylene sulfide to polyarylene sulfoxide using nitric acid

摘要

The invention relates to a process for the oxidation of polyarylene sulfide to polyarylene sulfoxide by means of nitric acid, in which the resulting polyarylene sulfoxide has a proportion of sulfoxide groups in the polymer chain of = 98%. According to the invention, polyarylene sulfide is treated with nitric acid in a concentration in the range from 60 to 80% with simultaneous exposure to heat. The polyarylene sulfoxide produced by the process according to the invention can be used outstandingly as a chemical blowing agent for foaming thermoplastics.