Photodegradation of Polystyrene Films Containing UV-Visible Sensitizers (original) (raw)
Related papers
Study of The Photostbilization Of Polystyrene In The Presence And Absence Of Schiff Base Derivatives
2022
Abatract The initiated photodegradation of polystyrene films notice able all around were examined (for 400 hrs.) in the being and absence of Schiff bases for benzoxazin product compounds by quickened weathering analyzer. The adding of (0.1% wt/v) of organic compounds to polystyrene films (thickness, 25μm) diminished the degradation of the polystyrene. The rate of degradation was trailed by an expansion in absorbtion of carbonyl for polymers utilizing viscosity, I.R., and UV spectra estimation. As per the results, the initiated degradation instruments of polystyrene films were recommended under the exploratory term utilized utilizing temperature 45 oC, radiation of UV at λ = 313 nm , illumination force 3.49x10-5 einsteins.dm-3.S-1.
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.
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.
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.
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.
Polymer Bulletin, 1982
The aim of this work was to investigate the influence of UV light absorbing additives on the rate of ultra violet light initiated degradation of polystyrene (PS) in solutions. Anthracene (ANT), chloranil (CA) nitrobenzene (TNB) which can form cnarge transfer complexes between each other were used. It was found for illuminated PS-solutions by light of X=254 nm that independently of the screening efficiency of these compounds, the formed CT complexes ANT-CA and ANT-TNB cause a decrease of the rate constant of degradation and of the value of the number average of cnain scission S. This effect is due to the energy transfer from the excited polymer chain segments to the low energy triplets of these CT-complexes thus hindering the rection of polymer chain segments with oxygen leading to slowing down of photodegradation.
On the photolysis of chain-chlorinated polystyrene
Journal of Photochemistry and Photobiology A: Chemistry, 1995
Copolymers of styrene and a-chlorostyrene containing 19%-95% a-chlorostyrene, prepared by photochlorination of polystyrene (PSt), were irradiated with UV light at hint = 254 nm (continuous irradiation) or at Ainc = 266 nm (flash photolysis). The major photochemical reactions occurring in films of highly chlorinated polymer (CPSt-95, TC1=0.95 El atoms per repeating unit) are chlorine release ~b(HC1) = 2 X 10-2) and the accompanying formation of carbon-carbon double bonds. Main-chain scission is a minor process of quantum yield ~b(S) = 2 × 10-3, but brings about a decrease in the average molar mass of CPSt-95. Flash photolysis studies revealed the existence of ~inglet excimers (~'~< 20 ns), triplets (z-65 ns) and benzyl-type radicals (z>~ 5 ms). The quantum yields of chlorine release and formation :)f benzyl-type radicals, measured in tetrahydrofuran solution, are of equal magnitude (about 0.2). By contrast, photochemical reactions in :opolymers of low chlorine content resemble those induced in polystyrene, e.g. at 3'cl =0.19 intermolecular cross-linking dominates over main-chain cleavage and renders the polymer insoluble.
Polymer Degradation and Stability, 1981
Processing of polystyrene at 160°C for different periods in the closed chamber of a Brabender Plastograph results in no appreciable oxidation. Therefore, the photooxidative stability of the polymer, as measured from retention of the ultimate tensile strength, is not affected by such treatment. On the other hand, acetophenone groups, the concentration of which increases with processing time, are produced at 160°C in the open chamber of the Plastograph as a consequence of extensive thermal oxidation. A quantitative correlation is found between the rate of change of the ultimate tensile strength of polystyrene and the extent of thermal oxidation. It is also demonstrated that a phenolic antioxidant, although it efficiently inhibits the thermal oxidation, has no specific effect on the photo-oxidation of polystyrene. A hindered amine light stabiliser, however, exhibits a pronounced photo-protective effect. A mixture of these additives combines the benefits of both.
International Journal of Chemistry, 2012
The photostability of thin films of poly (Fluorostyrene) isomers was studied by irradiation with UV-light, in presence of air at room temperature. The irradiated polymer films were exposed to different intervals of time and the degradation process was investigated with absorption, fluorescence and FT-IR spectroscopic methods. The influence of phthalate and terephthalate plasticizers on photo-oxidative degradation was also investigated. Blending with these plasticizers was found to decrease the stability of the irradiated polymers. The same observation was noticed in the photodegradation of other substituted polystyrenes films. The intensity of absorption was also found to increase with time of irradiation and in the intensity of a new absorption band at longer wavelength. In addition the formation on new fluorescence band at longer wavelength for the irradiated film is an evidence of photodegradation of the irradiated polymer films. The FT-IR spectra of irradiated polymers and for blended polymer films with phthalates and terephthalate, showed an increase in the absorption bands of these isomers indicating the possibility of degradation. The mechanism of photodegradation of these isomers was found to be similar to that of polystyrene. The order of photostability of these isomers was found that poly (p-fluorostyrene) is the most stable isomer and, poly (o-fluorostyrene) is the lowest stable isomer towards irradiation effect.
Macromolecules, 1993
Exposure to ultraviolet (UV) radiation may cause the significant degradation of many materials. UV radiation causes photooxidative degradation which results in breaking of the polymer chains, produces free radical and reduces the molecular weight, causing deterioration of mechanical properties and leading to useless materials, after an unpredictable time. Polystyrene (PS), one of the most important material in the modern plastic industry, has been used all over the world, due to its excellent physical properties and low-cost. When polystyrene is subjected to UV irradiation in the presence of air, it undergoes a rapid yellowing and a gradual embrittlement. The mechanism of PS photolysis in the solid state (film) depends on the mobility of free radicals in the polymer matrix and their bimolecular recombination. Free hydrogen radicals diffuse very easily through the polymer matrix and combine in pairs or abstract hydrogen atoms from polymer molecule. Phenyl radical has limited mobility. They may abstract hydrogen from the near surrounding or combine with a polymer radical or with hydrogen radicals. Almost all synthetic polymers require stabilization against adverse environmental effects. It is necessary to find a means to reduce or prevent damage induced by environmental components such as heat, light or oxygen. The photostabilization of polymers may be achieved in many ways. The following stabilizing systems have been developed, which depend on the action of stabilizer: (1) light screeners, (2) UV absorbers, (3) excited-state quenchers, (4) peroxide decomposers, and (5) free radical scavengers; of these, it is generally believed that excited-state quenchers, peroxide decomposers, and free radical scavengers are the most effective. Research into degradation and ageing of polymers is extremely intensive and new materials are being synthesized with a pre-programmed lifetime. New stabilizers are becoming commercially available although their modes of action are sometimes not thoroughly elucidated. They target the many possible ways of polymer degradation: thermolysis, thermooxidation, photolysis, photooxidation, radiolysis etc. With the goal to increase lifetime of a particular polymeric material, two aspects of degradation are of particular importance: Storage conditions, and Addition of appropriate stabilizers. A profound knowledge of degradation mechanisms is needed to achieve the goal.