UV-Irradiation Effect on the Photodegradation of Plasticized Poly (Ortho, Meta, and Para-Fluorostyrene) Isomers in Solid Films (original) (raw)
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Journal of Materials Science and Engineering B
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.
Irradiation Effect on Photodegradation of Pure and Plasticized Poly (4-Methylstyrene) in Solid Films
Materials Sciences and Applications, 2014
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.
Irradiation Effect on Stability of Plasticized Poly(Fluorostyrene) Isomers in Solution
International Journal of Photochemistry, 2014
The UV irradiation and blending effects on stability of Poly(Fluorostyrene) isomers in solution were studied at different intervals of irradiation time in presence of air. The increase in irradiation time of these isomers caused an increase in the intensity of the absorption band and an increase in the intensity of the absorption of new broad band at longer wavelength, thus indicating a possibility of photodegradation of polymeric chains. The influence of added dioctyl phthalate and dioctyl terephthalate plasticizers on photooxidative degradation was also investigated and was found to increase the photodegradation processes in polymeric chains. On the other hand, the intensity of excimer and monomer fluorescence bands maxima was also found to decrease with increase in irradiation times. These changes may be attributed to the formation of new photoproducts resulted from the photodegradation of irradiated polymeric chains. The decrease in polarity of used solvents caused a considerabl...
Materials Sciences and Applications, 2010
The photodegradation of thin films of poly (4-chlorostyrene) and poly (4-bromostyrene) with 265 nm radiation in the presence of oxygen and as a function of irradiation time has been studied mainly using fluorescence, FT-IR, and UV-VIS spectroscopic techniques. The influence of phthalate and terephthalate plasticizers on photo-oxidative degradation was also investigated. Phthalate and terephthalate-plasticizers were found to increase the photodegradation processes in polymeric chains. On the other hand, the intensity of absorption was also found to increase with irradiation time and in the intensity of a new absorption band at longer wavelength. The appearance of new fluorescence bands in the irradiated polymer films can well indicate a possibility of photodegradation of polymer films. In addition, the observed increase in the intensities of the carbonyl and hydroxyl regions of the FT-IR spectra, providing evidence for the photodegradation as well as the photo-oxidation of polymeric chains. The increase in the analyzed ranges was attributed to the formation of alcohols, aliphatic ketones and to the increase in the number of (C=C) that resulted from hydrogen abstraction during chains-scission.
Kinetic Study of the Effect of Plasticization on Photodegradation of Polystyrene Solid Films
Materials Sciences and Applications, 2015
The effects of UV-irradiation on stability of pure and blended polystyrene films with phthalate and terephthalate plasticizers were studied in presence of air. UV-visible, fluorescence and FT-IR techniques were used to study the photodegradation of irradiated polystyrene films. Increase of irradiation times of polystyrene films caused an increase in the intensity of the main absorption band and the increase in the intensity of a new absorption band at longer wavelength, thus indicating a possibility of photo degradation of polystyrene chains. The influence of added plasticizers, dimethyl terephthalate, diethyl terephthalate, dioctyl terephthalate, dioctylphthalate, and dibutyl phthalate on photo-quenching of the polymer fluorescence band was also investigated, and found to increase the photodegradation processes in polymeric chains. On the other hand, the intensity of excimer and monomer fluorescence bands maxima was also found to decrease with a small red shift with the increase in irradiation times. These changes may be attributed to the formation of new photo-products resulted from the photodegradation of irradiated 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 percent of added plasticizers, indicating that the added plasticizers might act as UV-absorbers which inhibited the photodegradation process. The analysis of the FT-IR spectra of the irradiated and nonirradiated samples showed a noticeable formation of new broad band centered at 1727 cm −1 , and its 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 provided evidence for the photodegradation as well as photo-oxidation of polymeric chains.
Materials Sciences and Applications, 2017
The effect of UV irradiation and blending with phthalate and terephthalate plasticizers on the photo-stability of Poly (4-vinyl biphenyl) was studied at different intervals of irradiation time and in presence of air. The increase in irradiation time on the photodegradation of polymer thin films caused a change in the intensity and shape of the fluorescence band. It has been found that the stability of the polymer decreases with the increase of irradiation time, and to increases with the increase of the amount of added phthalate and terephthalate plasticizers, which is evidence of polymer photodegradation. The FT-IR spectra of irradiated pure and blended polymer with phthalate and terephthalate plasticizers showed a decrease in some absorption bands and increase in the other bands, this is also another factor for the occurrence of photo degradation of the irradiated polymer. The increase in the intensity of absorption of carbonyl and hydroxyl region, indicates a possible photogegrada...
Polymer Degradation and Stability, 1999
The photodegradation mechanism of polymers highly depends on the type and concentration of chromophores present. This in¯uence is studied by making a comparison between the UV-degradation of PE, PP, PA6 and PBT and the thermooxidative degradation of PP at a comparable temperature. The degradation processess are followed by determining the oxygen uptake, CO, CO 2 and peroxide formation. During UV-degradation of PP, PE, PA6 and PBT the oxygen uptake is linear in time without an induction period. The oxidation rate of PP is higher than that of PBT, which is slightly higher than the oxidation rate of PA6, while that of PE is the lowest. The determined amount of peroxides depends on the ageing time. For the UV-degradation this does not lead to the expected increase of the oxidation rate, as is the case with thermooxidation of PP. Only a limited proportion of the peroxides formed during the UV-degradation decomposes into radicals. The oxidation rate is mainly determined by other radical forming reactions. In the case of PE and PP this is probably initiation by polymer-oxygen Charge Transfer Complexes (CTCs) and for PA6 and PBT direct photolysis of the amide or the ester linkage, respectively. Thickness degradation pro®les show that the UVdegradation processes of PP and PBT are heterogeneous. For PP this is due to oxygen diusion limitation, while in the case of PBT it is the result of absorption of the UV-light. #
Degradation of acrylonitrile-butadiene-styrene and polycarbonate by UV irradiation
Polymer degradation and stability, 2000
The eects of ultra-violet irradiation on the microstructure of an oxygen free polymer viz., acrylonitrile-butadiene-styrene and a polymer containing oxygen viz., polycarbonate have been investigated using positron annihilation lifetime measurement. Lifetime results in both polymers in the early stages of irradiation indicate that chain-scission leading to free radical formation is the predominant process. Radiation induced cross-linking becomes dominant in the later stages of irradiation. An interesting feature observed in the present studies is that an oxygen containing polymer attains free volume stability which is attributed as due to the formation of photostabilisers whereas no such stability is observed in the case of an oxygen free polymer. UV absorption spectroscopy results supplement the positron lifetime results that oxygen containing polymer becomes photostabilised. #
Photodegradation kinetics of poly(para-substituted styrene) in solution
Polymer Degradation and Stability, 2008
The UV irradiation effects on stability of polystyrene, poly(4-methoxystyrene), poly(4-methylstyrene), poly(a-methylstyrene), poly(4-tert-butylstyrene), poly(4-chlorostyrene), and poly(4-bromostyrene) in dichloromethane, dichloromethane, tetrahydrofuran, and N,N-dimethylformamide solutions were studied in the presence of oxygen at different intervals of irradiation time. The photodegradation was studied at 293 K using fluorescence spectroscopy. Solutions of these polymers were accompanied by quenching of monomer and excimer emissions during the exposure of their solutions to UV light, and by a change in the structure of the fluorescence spectrum. Irradiation of poly(4-methylstyrene) and poly(amethylstyrene) at excitation wavelength of 265 nm showed an increase of fluorescence intensity of a broad band, at longer wavelength without clear maxima. This may indicate that photodestruction of these polymers by irradiation with light of frequency absorbed by the polymer, may start from a random chain scission, with the possibility of formation of polyene and carbonyl compounds.
Photooxidative degradation of polyether-based polymers
Macromolecular Symposia, 1999
The mechanisms of photooxidation of several polyether based polymers were compared in order to give general rules of orientation of the oxidative reactions. These polymers were a poly(ether-ester) and two poly(etherurethane)s. The behavior of the polyether component as homopolymer was also studied. This study was extended to copolymers of fluorinated olefins and ally1 or vinyl ethers, and the non fluorinated homologues. The elucidation of the photooxidation mechanisms was based on the identification of the photoproducts by analysis of both the solid polymeric matrix and the gaz phase formed on irradiation. It was shown that the photochemical sensitivity of the polyether component was responsible for the rapid oxidation of the copolymers. However, in the case of the fluorinated compounds, different behaviors were observed. It was shown that the presence of the fluorine atoms strongly influenced the orientation of the reaction and modified the oxidation kinetics. The reactivity of the methylene groups in a-position of the oxygen atom of the ether groups were not found to be equivalent regarding oxidation and the secondary was more oxidizable than the tertiary one.