Antistatic polyphenylene oxide by surface sulfonation

Polyphenylene oxide was surface‐sulfonated with chlorosulfonic acid to provide antistatic properties. Optimal treatment time was shown to be 2–3 mins with a saturated solution of the acid in hexane or 25–30 mins using acid vapor‐saturated air under the given experimental conditions at room temperature. Being sensitive to humidity, the resistivity of the treated surface was lowered to the magnitude of 10 7 to 10 8 ohm/square at 43 percent relative humidity and to 10 11 at 10 percent relative humidity. The vapor phase method was found to be superior to the solution method with respect to the durability of the treated surface against water washing. Microscopic examination revealed extensive surface erosion by the solution treatment.