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.

The photodegradation of poly(fluorostyrene) isomers with different amounts of phthalate and terephthalate plasticizers has been investigated with the aid of Fourier‐transform infrared spectroscopy. Photo irradiation was carried out with light from a Hydrogen‐Xenon lamp at 265 nm and 293 K. As irradiation time increased, changes occurred in the structure of the polymers due to the destruction of polymeric chains and the formation of new photo products during the degradation. The photo products caused shifts, an increase or decrease of the polymer vibrational frequencies, as well as changes in numerous infrared band intensities. The increase in the intensities of the analyzed ranges is attributed to the formation of carbonyl, hydroxyl, and aliphatic ketones and to the increase in the number of polyene structures that resulted from hydrogen abstraction during photodegradation reactions. The analysis of the Fourier‐transform infrared spectra of the irradiated and nonirradiated samples showed a noticeable formation of a new broad band centered at (1,727 cm−1, C=O), assigned to the growth of aliphatic ketones formerly from the reaction of reactive alkoxy radicals. Its intensity was found to increase with the increase in irradiation time and also with the increase in the amount of added terephthalate and phthalates plasticizer, indicating an increase in the efficiency of the photo degradation process. Trends of photostability of these isomers were found such that poly(para‐fluorostyrene) > poly(meta‐fluorostyrene) > poly(ortho‐fluorostyrene). The photodegradation process for these plasticized isomers was found to increase by the increase in the bulkiness of the plasticizer molecule. J. VINYL ADDIT. TECHNOL., 24:75–83, 2018. © 2015 Society of Plastics Engineers

The photodegradation of irradiated thin films of poly (para-ethoxystyrene) with 265 nm radiations in the presence of air and as a function of irradiation time has been studied using UV-VIS, fluorescence and FT-IR spectroscopic techniques. The increase in irradiation time caused an increase in the intensity of the absorption band of the polymer, thus indicating a possibility of photodegradation of polymeric chains. The influence of increase in irradiation times on pure poly (ethoxystyrene) films caused a decrease in the intensity of the fluorescence band and the appearance of new broad band at longer wavelength and to decrease with increase in irradiation time. The influence of added phthalate and terephthalate plasticizers on photo-oxidative degradation was also investigated, and found to increase the photodegradation processes in polymeric chains. The photo-quenching rate constant was found to increase with the increase of the molar mass and bulkiness of the used plasticizers and to increase with the increase in irradiation time. The rate constant of the photo quenching process was found to decrease with the increase in the amount of added plasticizers, indicating that the added plasticizers may act as UV-absorbers which inhibit the photodegradation process. The analysis of the FT-IR spectra of the irradiated and non-irradiated samples, showed a noticeable formation of new bands, and their intensity was found to increase with the increase in irradiation time and also with the increase in the amount of added plasticizer. In addition, the observed increase in the intensities of the carbonyl and hydroxyl absorption regions of the FT-IR spectra, provide evidence for the photodegradation as well as photo-oxidation of polymeric chains.