Solid-state polymerization of acrylic acid initiated by polarized ultra-violet radiation

Abstract

The mechanism of radical formation in the ultra-violet-initiated solid-state polymerization of acrylic acid has been investigated by the use of polarized radiation. At low conversions, the rate of reaction is determined by the orientation of the monomer crystal in the polarized radiation. It is concluded that absorption of ultra-violet radiation by the crystalline monomer produces mobile excitons. The excitons are trapped in lattice imperfections where they decay by non-radiative processes to produce free radicals in the imperfections and to assist processes other than radical formation by enhancement of local molecular motions.