Study on the preirradiation polymerization of vinyl monomers

This paper presents mainly the polymerization, copolymerization and crosslinking of monomers off-source induced by peroxides which are formed by high energy irradiation of vinyl monomers such as styrene (St), acrylonitrile (AN), methylmethacrylate (MMA), vinyl acetate (VAc) and 2-hydroxyethyl methacrylate (HEMA). The peroxides produced by irradiation of the above mentioned monomers can not only induce the monomers themselves, but also another non-irradiated monomer to carry out co-polymerization efficiently. The activation energy of peroxide formation, the apparent activation energy of polymerization and the activation energy of peroxide initiation by irradiation of vinyl monomers are: Esub(f[MMA]) = 11, Esub(f[St]) = 9.6, Esub(f[AN]) = 8.5, Esub(MMA) = Esub(VA) = 11.4, Esub(i[MMA]) = Esub(i[VA]) = 13 kcal/mol. The rate of decomposition of monomer peroxides is smoother than that of BPO during the polymerization and so a smooth kinetic progress is obtained. The initiating ability of forming peroxides by irradiation of the vinyl monomers depends mainly on the chemical structure of the monomers. (author)