The Radiation-Induced Graft Polymerization of Methyl Methacrylate and Cellulose

The quantitative effects of certain factors on the radiation-induced graft polymerization of methyl methacrylate (MMA) and paper (cellulose) were determined. All irradiations were performed in a medium-intensity gamma radiation field created by neutron activation of ⁵⁵Mn. Resultant radiation dose rates varied between 1.4 and 3.2 × 10⁵ rads/h, initially, and diminished with a 2.58-h half-life. Sample preparation was an important variable in that paper samples immersed in MMA and irradiated immediately thereafter exhibited no grafting, whereas samples soaked 4 and 24 h prior to irradiation yielded increasing amounts of grafting for the same radiation dose. Hydroquinone, which serves as an ideal inhibitor for bulk MMA, yielded no induction period at all for the MMA-cellulose system. The effects of oxygen on the graft polymerization of MMA were similar to its effects on the homopolymerization of MMA. The use of acetone as a solvent for MMA enhanced the amount of graft polymerization. Even higher yields per absorbed dose were obtained using a water-acetone-MMA solution. Furthermore, no pre-irradiation “soak” was necessary to achieve grafting at relatively low absorbed doses in the MMA-solvent systems.