Accelerated photo‐oxidation of polyethylene. II. Further evaluation of selected additives

Taylor, Lynn J.; Tobias, John W.

doi:10.1002/app.1981.070260908

Cited by 12 publications

(6 citation statements)

References 15 publications

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“…The addition of photosensitive, unstable compounds to polymer matrix significantly changes photostability. [14][15][16][17][18] We choose organic compounds, which absorb UV-radiation and function as photoinitiators or photosensitisers in polyethylene (PE) decomposition.…”

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confidence: 99%

Photochemical Properties of Polyethylene Modified by Low-Molecular Organic Compounds

Kaczmarek

Ołdak

Podgórski

2003

Polym J

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ABSTRACT:Commercial polyethylene (LDPE) was physically modified by low-molecular organic compounds for acceleration of photodegradation. Two ketones (acetophenone, benzophenone) and two aromatic chloro-derivatives (benzyl chloride and 1-chloromethyl naphthalene) in the same amounts (1%wt) were used for PE modification. The influence of UV irradiation on thin films of doped PE was studied using Fourier transform infrared (FT-IR) and UV-vis spectroscopy. Much higher yields of photoprocesses in polyethylene (PE) containing modifiers were confirmed. Effectiveness of modifier depends on chemical structure and absorption of incident UV-radiation. The possibility of obtaining of degradable packaging films based on modified PE is suggested.

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confidence: 99%

Photochemical Properties of Polyethylene Modified by Low-Molecular Organic Compounds

Kaczmarek

Ołdak

Podgórski

2003

Polym J

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“…It seems however possible that the aromatic peaks and the peaks between 4 and 5 ppm are part of the same fragments. Unfortunately, the concentration of the solution is too low to record 13 C NMR, which would have eased further interpretation. The peaks between 4 and 5 ppm appeared in the sensitized reaction and are more intense compared to the lignin peak intensities at 0 h. Furthermore, 2D NMR for sensitized reactions could not be recorded in good quality due to the intense benzophenone peaks.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…17 Additionally, hydrogen abstraction can create radicals on polymers, which can undergo chain scission reactions upon reactions with molecular oxygen. 13,18 However, creation of radicals on lignin can also lead to undesired repolymerization. 19 Hypothesized mechanisms for hydrogen abstraction and chain scission are shown in Scheme 1.…”

Section: ■ Introductionmentioning

confidence: 99%

Insights into Photosensitized Reactions for Upgrading Lignin

Riddell

Hynynen

Baena‐Moreno

et al. 2023

ACS Sustainable Chem. Eng.

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The conversion of lignin into valuable chemical products is important for the shift away from the petrochemical industry toward a more sustainable system of biorefineries. However, the recalcitrance and heterogeneity of lignin have made its selective depolymerization a difficult task. Photochemical methods of lignin conversion are being investigated because of the potential to operate photoreactors at milder temperatures and pressures than thermal methods and to achieve efficient reaction pathways. Furthermore, light-driven reactions facilitate reaction pathways that cannot be accessed by conventional/thermal methods. Most of the current research focuses on photocatalytic methods, which are interesting due to their potentially high selectivity, but come with the disadvantage of catalyst costs and separation requirements. In this work, we continue our investigation into the use of ultraviolet light-emitting diodes, which aims to utilize the advantages of photochemistry, while avoiding the use of expensive catalysts. Photosensitizers can participate in energy transfer, electron transfer, and hydrogen abstraction in photochemical reactions. Here, we investigated the effects of a common photosensitizer, benzophenone, on the photochemical conversion of lignin, and 2-(benzyloxy)phenol (2BP), a compound with an ether bond between two aromatic units. We monitored the conversion reactions using complementary techniques of 1H nuclear magnetic resonance (NMR), diffusion NMR, and in situ Fourier transform infrared (FTIR) spectroscopy. For 2BP, the reactions with benzophenone progressed slower and without a difference in the final product formation. However, several differences were observed in photoreactions utilizing Kraft lignin and benzophenone compared to those without benzophenone. For example, a faster decay of the 1H NMR peak corresponding to aromatic/phenolic protons and different changes in the shape of methoxy peaks were observed, indicating the formation of different products. This work demonstrates that benzophenone participates in the photoreactions of Kraft lignin and that the photoreactions of Kraft lignin and 2BP are different. Depolymerization of lignin into smaller fragments was confirmed with diffusion NMR, both with and without the photosensitizer.

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“…Polyolefins can degrade with exposure to external factors, such as sunlight irradiation, temperature, and humidity, in outdoor applications . λs in the range between 280 and 800 nm have sufficient energy to cause a cleavage of the chemical structure of the polymer . Photooxidation in polyolefins takes place when free radicals are generated through energy transfer, mainly at chromophores, double bonds of the polymer, or catalyst residues .…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5] ks in the range between 280 and 800 nm have sufficient energy to cause a cleavage of the chemical structure of the polymer. 6,7 Photooxidation in polyolefins takes place when free radicals are generated through energy transfer, mainly at chromophores, double bonds of the polymer, or catalyst residues. [8][9][10][11][12] The synergetic effect of ultraviolet-visible (UV-vis) radiation in the presence of oxygen changes the initial polymer chemical structure, 13 and this, consequently, influences the mechanical and thermal properties.…”

Section: Introductionmentioning

confidence: 99%

Protection of high‐density polyethylene–silicon composites from ultraviolet–visible photodegradation

Santonja-Blasco

Rodríguez

Sánchez-Ballester

et al. 2017

J of Applied Polymer Sci

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The extent of the ultraviolet–visible (UV–vis) photoirradiation effect on high‐density polyethylene (HDPE) and HDPE–silicon (Si) composites is reported in terms of the addition of Si microparticles at contents of 0.1, 1, and 5 wt %. A standard accelerated UV–vis exposure was applied over 2750 h, corresponding to 22 months in Florida. Thermogravimetry, differential scanning calorimetry, and Fourier transform infrared spectroscopy were used as reliable techniques for monitoring the quality of the HDPE–Si composites. The increasing addition of Si microparticles delayed the photodegradation of the HDPE–Si composites. Because of their strong light‐scattering effects, Si microparticles blocked the degradation of tertiary carbons of the HDPE backbone and reduced the apparition of vinyl groups; this prevented the structural impoverishment of HDPE–Si composites. Consequently, variations in the crystallization temperature (Tc) and melting temperature (Tm), which were indicators of photodegradation, were not modified. In general, the HDPE–Si composite formulation with 5 wt % Si microparticles was useful for protecting the material from photodegradation and, thus, should be an environmentally friendly, reliable alternative UV–vis blocker. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45439.

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Accelerated photo‐oxidation of polyethylene. II. Further evaluation of selected additives

Cited by 12 publications

References 15 publications

Photochemical Properties of Polyethylene Modified by Low-Molecular Organic Compounds

Photochemical Properties of Polyethylene Modified by Low-Molecular Organic Compounds

Insights into Photosensitized Reactions for Upgrading Lignin

Protection of high‐density polyethylene–silicon composites from ultraviolet–visible photodegradation

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