Radiation and thermal stability of PMMA modified by rare-earth metal ions

The properties of PMMA obtained by radiation-induced and thermal polymeriza tion and containing up to 16.0 wt % of rare-earth element (RE) ions were st udied. The molecular mass of PMMA depended on the method of polymerization and the concentration of modifying agent, decreasing from similar to 1 x 10 (6) in nonmodified samples obtained by the thermal polymerization to 1 x 10 (5) in the RE-ion-modified samples obtained by the radiation-induced proces s. Upon irradiation of the samples to a dose of 10 kGy, the molecular mass of PMMA decreases approximately by half; increase in the absorbed dose to 4 00 kGy or above leads to complete degradation of the materials. It was esta blished that the presence of RE ions produces a 10-15 degrees C increase in the thermal stability of PMMA.