Effect of acid on radiation grafting of functional monomers onto silicone rubber

The acid effect in mutual radiation grafting of acrylic acid (AA), 4-vinyl-pyridine (4-VP) and N-2-vinylpyrrolidone (N-NP) in methanol on silicone rubber was investigated. Measurements of grafting yields as a function of dose were carried out. In addition, the effects of Cu2+ and monomer concentrations in solvent were observed. It was found that acid in grafting system of 4-VP had enhancement effect, in N-VP system had inhibition effect with a wide absorbed dose range. But in the case of AA the relationship was more complex: below 6 kGy acid enhanced the grafting yield; while dose was up to 13 kGy the opposite results were obtained. The mechanisms of acid effects in the methanol systems were discussed. (author)