Joanna Kowal

Photo-oxidation of polystyrene film: 1. Photo-oxidation of polystyrene films with light absorbed by polymer

Abstract The photo-oxidation of polystyrene films irradiated with light absorbed by the polymer has been studied. The overall quantum yield of hydroperoxide as well as the relationship between the concentration of acetophenone-type carbonyl products and α,β-enone and diketone products were found. The spatial distribution of the different types of carbonyl products was investigated.

Photo-oxidation of polystyrene in dichloromethane solutions

Abstract Photo-oxidation of polystyrene in dichloromethane solution irradiated with light absorbed by the polymer was investigated. The quantum yields of the formation of acetophenone-type carbonyl compounds as well as α, β-enone and dicarbonyl products were calculated based on the analysis of u.v. absorption spectra of irradiated solutions. The relationship between the concentration of these products was found.

Photo-oxidation of polystyrene film: 2. Photo-oxidation of polystyrene film with light absorbed by the polystyrene-oxygen complex

Abstract Photo-oxidation of polystyrene films prepared from carefully purified polymer, irradiated with light absorbed only by a polystyrene-oxygen complex has been studied. It was found that photo-oxidation of polystyrene under such conditions results in carbonyl compound and hydroperoxide formation. Photo-oxidation of polystyrene with light of a frequency abosrbed by the polystyrene-oxygen complex occurs throughout the whole volume of sample.

Photochemical processes of 2,6-di-tert-butyl-4-methylphenol

Abstract The photosensitized oxidation of 2,6-di-t-butyl-4-methylphenol (BHT) by anthracene (A) in CCI4, hexane and polystyrene films with light of wavelength 365 nm has been investigated. Interestingly, BHT was found to inhibit the consumption of A in the presence of oxygen. A possible kinetic scheme for the reaction of A + BHT + CCl4 has been devised; the rate constants for the most important processes have been evaluated.

Photochemical reactions of pentaerythrityl tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and dicumyl peroxide in hexane solution and polystyrene films

Abstract The photochemical reactions of pentaerythrityl tetrakis[3-(3,5-di- tert -butyl-4-hydroxyphenyl)propionate] (Irganox 1010; IH) and dicumyl peroxide (DCP) initiated by long-wavelength radiation with λ >300 nm in hexane solutions and polystyrene films were studied. It was found that the rate of formation of acetophenone (APH) in the photolysis of DCP in hexane solution is lowered in the presence of IH and the rate constant for the reaction between alkoxyl radical RO • and IH is about 10 3 times greater than the sum of the rate constants for APH formation and hydrogen abstraction from solvent molecules by RO • . The consumption of IH was confirmed during the irradiation of PS films containing DCP and IH. The decrease in the rate of APH formation and the inhibiting effect on the photodegradation of the polymer were observed.

Hypochromism of poly(2-vinylpyridine), poly(2-vinylnaphthalene) and polyacenaphthylene

The u.v. hypochromy of poly(2-vinylpyridine) of different degree of isotacticity, atactic poly(2-vinylnaphthalene) and polyacenaphthylene in relation to 2-ethylpyridine, 2-ethylnaphthalene and acenaphthene, respectively, was evaluated. In the case of poly(2-vinylpyridine) the hypochromic effect was greater for an isotactic-rich sample (8.2%) than for an atactic one (4.8%). The decrease in absorption intensity of polymers containing naphthalene chromophores was compensated by broadening of the u.v. bands and the hypochromy was relatively small: 4.7% for poly(2-vinylnaphthalene) and 4.3% for polyacenaphthylene.

Effect of dicumyl peroxide on photo-oxidation of polystyrene films: 2

Abstract The effect of dicumyl peroxide on the photo-oxidation of polystyrene film has been studied using light of a wavelength absorbed by the polystyrene—oxygen complex. Energy transfer from the excited polystyrene—oxygen complex to the peroxide present in polystyrene film was considered to be the process of most importance in the initiation of polystyrene long-wave photo-oxidation.