Irradiation Effect on Photodegradation of Pure and Plasticized Poly (4-Methylstyrene) in Solid Films

Abstract

The photodegradation of irradiated thin films of poly (para-methylstyrene) with 265 nm radiations in the presence of airand as a function of irradiation time has been studied using UV-VIS, fluorescence and FT-IR Spectroscopic techniques. The influence of phthalate and terephthalate plasticizers on stability of poly (para-methylstyrene) towards irradiations was also investigated. Blending with phthalate plasticizers was found to cause a higher efficiency of photodegradation than that obtained in doping with terephthalate plasticizers. The intensity of absorption was also found to increase with time of irradiation and in change in the shape of the spectra at longer wavelength, thus indicating a possibility of photodegradation of polymer chains. The analysis of the FT-IR spectra of the irradiated and non-irradiated samples, shows a predominant absorption associated with carbonyl compounds with 1740 cm −1 . In addition, the observed increase in the intensities of the carbonyl and hydroxyl regions of the FT-IR spectra, have provided an evidence for the photodegradation as well as photo-oxidation of polymeric chains. The presence of the plasticizer in the polymer backbone was found to accelerate the photodegradation of polymeric chains.

Study the Influence of UV-Irradiation on the Photo Stability of Pure and Plasticized Poly (4-Vinyl Biphenyl) in Solid Films

“…It is more likely that this red shift occurs as result of photodegradation of the polymeric chains, and can be attributed to the formation of conjugated double bonds along the polymer chain during the photodegradation by hydrogen abstraction process [36] [42]. The shift in the excimer fluorescence band is in good agreement with that reported with irradiated blended polystyrene [8], poly (4-methoxystyrene) [30] and poly (4-methylstyrene) [32]. Tovborg and Kops [36] pointed out that quenching of polymeric emission might be attributed to the energy transportation of the oxides formed by the photo-oxidation of polymeric chromophores, or to the quenching effect of the peroxide formed during UV-irradiation.…”

“…Phthalate and terephthalate as additives to substituted polystyrene causes an increase in its flexibility, but increase the stability of the polymeric chains [26] [27]. It was also found that the photo-stability of polystyrene was reduced by the addition of bromine-containing flame retardants, carbonyl group, or poly vinyl acetate, and appeared to depend upon the chemical structure of the polymeric additives [28]- [32]. It was found that the increase in the amount of doped plasticizers decrease the stability of polymeric chains and the increase in irradiation time of the UV-light causes also an increase in the efficiency of photodegradation process [33]- [39].…”

“…It was found that the increase in the amount of doped plasticizers decrease the stability of polymeric chains and the increase in irradiation time of the UV-light causes also an increase in the efficiency of photodegradation process [33]- [39]. In many recent studies, it was found that blending with phthalate plasticizers were more efficient in increase in the photodegradation of polymeric chains than blending with terephthalate plasticizers [30] [31] [32].…”

Fourier‐transform infrared spectroscopic study of plasticization effects on the photodegradation of poly(fluorostyrene) isomers films

“…It may be due to lowering in the stability of the energy transfer complex between the polymeric chromophore and plasticizer molecule [5]. As can be seen from Tables (1-3), the changes in the intensities of many FTIR absorption spectra of irradiated blended PFS isomers were increased with the increase in molar mass of the used terephthalate plasticizers and the bulkiness of added plasticizers, a fact that correlates well with that obtained for the thermal degradation of plasticized poly(para-substituted styrene) solid films [6,20]. The trend of increases in the effi-ciency of photodegradation was found as DOT > DET > DMT.…”

“…A number of different photoproducts were reported. Polyene structures and carbonyl and hydroxyl compounds were the main products that resulted from the photo-oxidation of substituted polystyrene films [19][20][21][22].…”