RADIATION-INDUCED GRAFTING POLYMERIZATION BY THE ANIONIC MECHANISM

In the reported experiments, the radiation-induced grafting polymerization of phenylacetylene and 2-methyl-5-vinylpyridine (2M-5VPy) onto low-density polyethylene has been investigated under strict identical conditions, using crude and thoroughly dried monomers. In the case of thoroughly dried monomers, the radiation-induced grafting is performed by the combined (radical plus anionic) mechanism. The kinetics of radical and anionic grafting of 2M-5VPy are investigated in detail. The activation energies are 4. 8 plus or minus 0. 3 and minus 2. 7 plus or minus 0. 3 kcal/mole for the radical and anionic grafting, respectively. The initial rate of grafting is approximately proportional to the dose rate to the 0. 47 plus or minus 0. 03 and 0. 92 plus or minus 0. 03 power for the radical and anionic grafting, respectively. The initial rate of grafting is approximately proportional to monomer concentration to the 1. 55 plus or minus 0. 05 and 2. 1 plus or minus 0. 05 power for the radical and anionic grafting, respectively. These data conform to the contribution of the anionic mechanism in a thoroughly dried system. The mechanism of radiation-induced anionic grafting is discussed.