Copolymérisation radiochimique de l'acide acrylique avec l'acide methacrylique en masse et en solution

Abstract

The gamma-ray initiated copolymerization of acrylic and methacrylic acids was investigated in bulk and in hexane and methanol solutions. The reaction occurs in precipitating media except in the presence of 75% methanol. A “matrix effect”, characterized by auto-catalysis was found in all mixtures containing at least 80% acrylic acid. This effect disappears if the copolymer contains 50% methacrylic acid or more. A matrix effect was also observed in the presence of methanol for mixtures containing larger amounts of methacrylic acid. The reactivity ratios are r 1(MAA) = 2.3 ± 0.3 and r 2 (AA) = 0.30 ± 0.10 for reaction in bulk, in hexane solution and in the presence of 25 and 50% methanol. In the 75% methanol solution in which the reaction medium remains homogeneous the reactivity ratios are: r 1(MAA) = 6.0 and r 2 (AA) = 0.02. The results are discussed.