Photo-oxidation Of Polystyrene Research Articles

Dissolved Organic Matter Enhanced the Aggregation and Oxidation of Nanoplastics under Simulated Sunlight Irradiation in Water.

Nanoplastics (NPs) have become a new type of pollutant of high concern that is ubiquitous in aqueous environments. However, the transport and transformation of NPs in natural waters are not yet fully understood. In this study, the aggregation and photooxidation of NPs were assessed with nanosized polystyrene (PS) as an example, and the effects of dissolved organic matter (DOM) were investigated with Suwannee River fulvic acid (SRFA) as representative DOM. The results showed that simulated sunlight irradiation exhibited negligible effects on the aggregation of PS, while SRFA enhanced its heteroaggregation through hydrophobic interactions. In SRFA solutions, photooxidation of PS with a particle size of 200 nm was observed, which led to an increase in the O/C ratio on its surface at a rate of (2.20 ± 0.40) × 10-2 h-1. This indicates the promotional effect of SRFA on the oxidation of nanosized PS, which is attributed to the generation of the excited triplet state (3SRFA*), hydroxyl radicals (•OH), and singlet oxygen (1O2). Among these reactive species, 1O2 played a crucial role in the oxidation of PS. The findings in this study are helpful for an in-depth understanding of the environmental behavior of NPs in natural waters.

Phototransformation of Plastic Containing Brominated Flame Retardants: Enhanced Fragmentation and Release of Photoproducts to Water and Air.

Increasing attention is being paid to the environmental fate and impact of plastics and their additives under sunlight exposure. We evaluated the photodegradation of polystyrene (PS) films (∼100 μm) containing brominated flame retardants (BFRs): decabromodiphenylether (BDE-209), tetrabromobisphenol A (TBBPA), and tetrabromobisphenol A-bis (2.3-dibromopropylether) (TBBPA-DBPE). Irradiations were performed in a solar simulator and outdoors. Infrared (IR) analyses indicated an acceleration of the photooxidation rate of fire-retarded PS films compared to pure PS with an enhancement factor of 7 for TBBPA-DBPE and TBBPA, and 10 for BDE-209. The accelerating effect was found to be correlated with the quantum yield for BFR photodegradation and its absorbance in the PS films. The presence of BFRs also modified the PS photooxidation mechanism and resulted in the formation of 14 brominated photoproducts via bromination and oxidation of PS. Furthermore, a drastic increase in chain scissions and loss of molecular weight was revealed by size exclusion chromatography. This enhanced degradation of PS led to significant leaching (15%) of oxidation products from PS films after immersion in water, and to the gas-phase emission of several volatile brominated products. Our findings suggest that fire-retarded plastics may be a source of potentially hazardous contaminants when exposed to sunlight.

Vacuum UV photo-oxidation of polystyrene

Polystyrene (PS) was treated with vacuum UV (VUV) (λ = 104.8 and 106.7 nm) photo-oxidation and X-ray photoelectron spectroscopy detected a controlled increase in the atomic percentage of oxygen up to a saturation level of ca. 20 at% O. Initially, C–O and carbonyl groups are observed due to the formation of alcohols, ethers, esters, and ketones. Water contact angle measurements showed ca. 25% increase in hydrophilicity of the surface with oxidation. Atomic Force Microscopy observed little changes in surface roughness with treatment time. The super water absorbent polymer poly(acrylic acid) was thinly grafted to the modified PS surface.

Benzisoxazole 2‐oxides as novel UV absorbers and photooxidation inhibitors

Compounds with strong absorptions in the ultraviolet (UV) region of the spectrum, particularly the UVA and UVB, have seen much interest as UV screeners or absorbers in a wide variety of commercial products. A series of benzisoxazole 2‐oxides have been synthesized and characterized by UV–vis spectroscopy. A number of derivatives have been shown to posses moderate to strong molar absorption coefficients in the UVB range (ca. 300 nm), the strongest being those derived from benzophenones. Three other derivatives containing additional electron withdrawing groups showed strong molar absorption coefficients in the UVA (ca. 340 nm). Solvent effects on the parent derivatives show changes in the molar absorption coefficients with little changes in the λmax values. Preliminary studies of these compounds as potential additives to prevent photooxidation of polystyrene showed considerable inhibition of polymer degradation with the parent unsubstituted benzisoxazole 2‐oxide compounds being the most effective. Copyright © 2013 John Wiley & Sons, Ltd.

XPS studies of poly(acrylic acid) grafted onto UV photo-oxidized polystyrene surfaces

UV photo-oxidation of polystyrene was achieved with 253.7 and 253.7/184.9 nm radiation in the presence of an atmospheric pressure of oxygen and analyzed by X-ray photoelectron spectroscopy as a function of treatment time. A methodical increase in the atomic percentage (at.%) of oxygen occurred during 253.7 nm activation up to 2 h of treatment time. Photo-oxidation with the 253.7/184.9 nm lamps resulted in a saturation level of ca. 35 at.% O. Initially, C–O and C=O groups were formed and then O–C=O type moieties. Poly(acrylic acid) was partially and/or thinly grafted onto the oxidized polystyrene surfaces.

Photochain destruction of excited peroxide polystyrene macroradicals

Photo-oxidation of the polystyrene (PS) includes two mechanisms—a hydroperoxide one and a photochain one (caused by the photosensitivity of peroxide macroradicals). A hypothetical scheme of the photochain dissociation of excited peroxide radicals has been proposed. The latter are destroyed during photo-oxidation of polystyrene to H 2O and CO 2. More then 90% of the oxygen absorbed is consumed according to the photochain mechanism.

Photo-oxidation of polymers 4. The dual mechanism of polystyrene photo-oxidation: a hydroperoxide and a photochain one

By comparing the quantum yields of initiation, O 2 absorption and formation of intermediate and final products a conclusion has been made that the polystyrene photo-oxidation process involves two mechanisms: a photochain (∼90%) and a hydroperoxide (∼1%) one. The photochain mechanism is based on the reaction of excited peroxide macroradicals dissociation (the kinetic chain length is 10 2–10 3 units), leading directly to formation of the main final products, H 2O and CO 2, whose yield is comparable with the quantity of the absorbed oxygen. The ordinary hydroperoxide mechanism, by which up to 10% of the radicals formed in the initiation stage are converted, includes an RO 2 • reaction with a macromolecule and hydroperoxide formation. A subsequent ROOH decomposition results in the scissions of the polymer chains and the formation of high-molecular oxidation products (carbonyls, alcohols, ethers).

Comparative analysis of the photo-oxidation of polystyrene and poly(α-methylstyrene)

The photo-oxidation of poly(α-methylstyrene) (PαMS) has been studied by FTIR and mass spectroscopy. The samples have been submitted to various conditions of irradiation under oxygen, with different irradiation sources and at several temperatures. SF 4 and NH 3 treatments and photolysis under vacuum have been carried out on the photo-oxidized samples. The results obtained were compared to those obtained in the same conditions of irradiation for polystyrene samples. An identification of the photoproducts is proposed with their main ways of formation.

Analysis of chain-scission and crosslinking rates in the photo-oxidation of polystyrene

A study of the chain-scission and crosslinking rates in polystyrene photodegraded in the laboratory with fluorescent tubes (UVA-340) was made using GPC molecular weight distributions. The analysis was based on the assumption that scission and crosslinking occur randomly and employed a Monte Carlo procedure to compute the changes in molecular weight distribution for chosen values of scission and crosslinking rates and compared the computed profiles with measurements made on the photodegraded samples. Results were obtained for three different exposures and at various depths within 3.2-mm-thick bars. The scission/crosslinking ratio, λ, was between 3 and 8 for all samples measured in this study. The lowest values of λ were found near the exposed surface and the highest near the bar center. Both scission and crosslinking rates were much lower in the interior, presumably the result of oxygen starvation. Some bars were exposed while loaded to 10 MNm−2 in uniaxial tension. The stress appeared to increase the reaction rates somewhat near the surface and to depress the rates in the interior correspondingly. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3015–3023, 2000

The photo-oxidation of polymers—3. The main reaction of chain propagation in polystyrene photo-oxidation

Abstract The photochain dissociation of peroxide macroradicals followed by effective absorption of oxygen and liberation of volatile products of destruction (H 2 O and CO 2 ) in the quantities comparable with the quantity of the absorbed O 2 is shown to be the main reaction of the chain propagation in photo-oxidation of polystyrene. (The reaction chain length is 10 2 –10 3 links.) The photochain reaction mechanism is confirmed by the special experiments with the participation of light at the stage of chain propagation when the photo-oxidation of polystyrene having the peroxide macroradicals was carried out under the action of longwave light with λ ≥440 nm, that was inactive to the starting polymer.

Photo-oxidation of polystyrene under load

The effect of a tensile stress on the rate of photo-oxidation of polystyrene was investigated. Molecular-weight measurements showed that tensile stress accelerates molecular scission in injection-moulded bars exposed to ultraviolet irradiation. Changes in the residual-stress distribution were observed during the exposure but they were not sufficient to reverse the sense of the residual stresses, and the residual stress near the surface remained compressive. Depth profiling indicated that the degradation process was oxygen-diffusion limited and an approximate analysis of the kinetics gave an activation energy for degradation of 4.2 kJm−2, which is also consistent with a diffusion process.

On the fate of the phenyl ring in polystyrene photooxidation

It is shown that the loss of aromatic structures from polystyrene (PS) during photooxidation with 254 nm UV cannot be explained by either volatilization or diffusion of low molecular weight photoproducts from the film surface. In view of the reactivity of phenyl rings in such a photooxidation environment, together with reported PS molecular weight changes that occur, it is clear that reactions occur on both the pendent phenyl ring and the PS backbone

The photo-oxidation of polymers—1. Initiation of polystyrene photo-oxidation

The initiation of polystyrene photo-oxidation has been studied and the quantum yield of initiation ( ϕ R ·) for u.v.-irradiation at 315 K in the presence of atmospheric oxygen has been found to be 10 −3. Using ESR spectra, five distinct free radicals have been found; their nature depends on the wave length of the light and the irradiation conditions (temperature and presence of oxygen).

1992 C R Burch prize TOF SIMS in polymer surface studies

This review describes advances made in the study of polymer surfaces at Sheffield University between 1988 and 1993. Over this period, we have taken advantage of the increased surface sensitivity, extended mass range, and imaging capability of Time-of-Flight Secondary Ion Mass Spectrometry (TOF SIMS) to investigate the surfaces of ‘as-received’, degraded, and modified polymers, as well as organic surface coatings prepared by plasma polymerization. This review is divided into six sections: 1. 1. Secondary ion mass spectrometry in polymer surface studies. 2. 2. The surface structure of polymer blends. 3. 3. The surface photo-oxidation of polystyrene (PS) and photostabilised PS. 4. 4. Monitoring the effects of plasma surface treatment by TOF SIMS. 5. 5. An investigation of plasma polymer structure. 6. 6. Conclusions and the future outlook for TOF SIMS. The first section gives a brief overview of the developments in SIMS technology and experimental methodology that now allow its routine use in polymer surface studies. The following four sections describe some selected data from the different projects in which we have been involved. In each, a short introduction to the topic is followed by a statement of the (original) objectives of our study. A summary of established results is presented along with some newer (unpublished) data. The intention is not simply to draw attention to what we have already done, but to give an idea of where our studies are progressing. The work described is ongoing, indeed, in all the examples selected for this review, more potential areas of investigation have been opened than closed. In the final section, the different themes of the preceding sections are brought together, and some weaknesses in the present use and understanding of SIMS, in polymer surface studies, are identified. Experiments designed to address these problems are described. In this section we also speculate on how recent advances in instrumentation could result in new applications.

Photooxidation of polystyrene by O2 and N2O

AbstractStrips of polystyrene held in a flowing O2 or N2O atmosphere have been exposed to 240‐600 nm radiation. The extent of photooxidation has been followed by x‐ray photoelectron spectroscopy (XPS). Although N2O is a more reactive gas than O2, it produces a less oxidized polymer surface. This surprising observation can be correlated to the photochemistry occurring at the gas/polystyrene interface. © 1992 John Wiley & Sons, Inc.

Polystyrene photooxidation. 2. A pseudo wavelength effect

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolystyrene photooxidation. 2. A pseudo wavelength effectBenedicte Mailhot and Jean Luc GardetteCite this: Macromolecules 1992, 25, 16, 4127–4133Publication Date (Print):August 1, 1992Publication History Published online1 May 2002Published inissue 1 August 1992https://doi.org/10.1021/ma00042a013RIGHTS & PERMISSIONSArticle Views350Altmetric-Citations60LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (678 KB) Get e-Alerts Get e-Alerts

Polystyrene photooxidation. 1. Identification of the IR-absorbing photoproducts formed at short and long wavelengths

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolystyrene photooxidation. 1. Identification of the IR-absorbing photoproducts formed at short and long wavelengthsBenedicte Mailhot and Jean Luc GardetteCite this: Macromolecules 1992, 25, 16, 4119–4126Publication Date (Print):August 1, 1992Publication History Published online1 May 2002Published inissue 1 August 1992https://doi.org/10.1021/ma00042a012RIGHTS & PERMISSIONSArticle Views867Altmetric-Citations96LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (837 KB) Get e-Alerts Get e-Alerts

The surface photo-oxidation of polystyrene: Part I—The application of ToF-SIMS to monitor changes in polymer chain length

ToF-SIMS has been employed to monitor the changes in molecular weight which occur on UV irradiation in a polystyrene standard (MW 1700) as a thin film on silver. The ToF-SIMS spectrum of unirradiated polystyrene is also described. Polysiloxane contamination was present in some of the polystyrene samples studied; no effort was made to remove this contamination as it was considered to be part of the system under analysis and proved useful in confirming the role of the phenyl substituent in the photodegradation of polystyrene. Implications of this study, the possible development of the technique described and its application to real polymer surfaces are discussed.

Plasma oxidation versus photooxidation of polystyrene

Plasma oxidation versus photooxidation of polystyrene

Initial steps in the photolysis and photooxidation of polystyrene

The effects of exposure of a number of differently prepared polystyrenes to long-wave u.v. ( λ ⩾ 300 nm) in O 2 were investigated. The polymers undergo two distinct phases of degradation, one associated with the initial decomposition of photo-labile structures, and the other with the photolysis of oxidation products, such as hydroperoxides. Polymers prepared under conditions of high free radical concentrations (higher temperatures and initiator concentrations) were the most reactive and contained more photo-labile structures. Hydroperoxides were prepared from these polymers and their degradations investigated. While hydro-peroxides act as initiators of the oxidative phase of the degradation, by producing radicals on photolysis, no convincing evidence was obtained for their participation in the initial photodecomposition. On the other hand, experimental data favoured the involvement of in-chain peroxides in this process. Differences of reactivity of polymer solutions and films were also observed, the apparent relative stability of films being attributed to the difficulty associated with the separation of large fragments in a more viscous medium.