Increasing the heat resistance of a polyphenylene oxide-based polymer by means of ionizing radiation

Czechoslovak polyphenylene oxide polymers, NERAFEN M in particular, were exposed to gamma doses of 10 to 1000 kGy using a 60Co source. Thermal resistance of the unfilled polymer can be improved by irradiation at above 150 degC. The polymer reinforced e.g. with glass fibres can be exposed to radiation with success. Permanency of form according to Martens was 20 to 30% increased on exposure to a dose of 100 kGy, whereas doses in excess of 200 to 300 kGy brought about a decrease in the thermal stability. Characteristic parameters of the polymers are tabulated in dependence on the dose applied. (P.A.). 1 fig. 4 tabs