Photodecomposition of polystyrene on long‐wave ultraviolet irradiation: A possible mechanism of initiation of photooxidation

Abstract

SynopsisThe long-wave (A > 3000 A) photo-oxidation of polystyrene in solution at 25°C has been studied osmometrically. Two types of chain scission have been observed: a purely photo process which occurs completely independently of oxygen and which is attributed to fission of photolabile groups in the polymer, and another process associated with random photolyses of the products of oxidation Scavenger experiments with I31I2 have shown that approximately two iodine atoms are incorporated per chain scission when photolysis is carried out in solution (benzene, hexafluorobenzene, methylene chloride) under high vacuum conditions in the presence of 1%.No iodine incorporation or chain scission occurs when ionically prepared polystyrenes are treated similarly. The nature of the photolabile bond has been discussed, and there is some evidence for a peroxidic linkage arising from oxygen copolymerization in the chains. It is suggested that fission of the photolabile groups contributes to the initiation of the long-wave photooxidation of the polymer.

A Study of Polymer Foam Blends for External Applications of Space Vehicle—2

“…Several investigations were carried out on photo degradation and photostabilization of PMMA [17,14,[18][19][20][21][22][23][24][25] and PS [26][27][28][29]. The bond strength of ester group (C=O) is 100 Kcal/mol which is equivalent to 280 my.…”

Ultra violet spectra studies of polystyrene films in presence of some transition metal complexes with 4-amino-5-pyridyl)-4h-1,2,4-triazole-3-thiol

“…The slope equal to the decomposition rate constant K d . Figure (2),(3), (4), (5), (6) and (7) shows the…”

“…One of the important uses of PS is in the manufacture of cover signal lamps of some automobiles (Safy Eldin and El-laithy, 1994), ). The photooxidative degradation processes of PS have been discussed in a number of reviews (Rabek and Ranby, 2003), (Lawrence and Weir, 2003). It is generally accepted that carbonyl formed during UV irradiation of polymers, is most probable and are responsible for the yellow coloration of the polymer (Mori et al 1979).…”

New aspects of photodegradation and photooxidation of polystyrene

“…Carbonyl groups absorb in the near ultraviolet, i.e. at 290 to 400 nm: >C=O + hv-1(>C-O) (5) __ (>ç0) (6) The carbonyl biradicals may further abstract hydrogen from the same or neighbouring macromolecules (HP):…”

“…during exposure outdoors. The photo-oxidation of polystyrene has been extensively investigated by many authors (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15). The main reactions observed are bond scission, chain crosslinking and oxidative degradation.…”