PHOTOOXIDATION OF POLYMERS - 2 - PHOTO-CHAIN REACTION OF PEROXIDE RADICALS IN POLYSTYRENE

ESR and optical spectroscopy methods were used to study the photo-conv ersion of peroxide macroradicals obtained on oxidation of radiolysed o r photolysed polystyrene. It is established that RO2. in PS possess ph otochromic characteristics (epsilon = 10(4)-4 x 10(3) M-1 cm(-1)) and under the action of light with lambda < 550 nm enters into photochemic al reactions. The rupture of C-C and C-H bonds leading to the formatio n of alkyl and allyl radicals is the main direction of their photo-con version. At 77 k the radical products of RO2. photolysis are stable, w hile under the conditions of PS photo-oxidation (at 300 k and in the p resence of O-2) there takes place a specific photo-chain reaction (cha in length is 10(2)-10(3) links), which is a sequence of alternating st ages of R-. oxidation and photo-dissociation of excited R-2(.) to give water and carbon dioxide. (C) 1998 Elsevier Science Ltd. All rights-r eserved.