Permanence of polymer stabilizers in hostile environments

Bell, Bruce M.; Beyer, D.; Maecker, N. L.; Papenfus, R. R.; Priddy, Duane B.

doi:10.1002/app.1994.070541103

Cited by 26 publications

(10 citation statements)

References 10 publications

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“…Besides the influence of food simulants and gamma irradiation, the effect of biotic and abiotic degradation [69], spa chemicals, and xenon arc exposure [70], systematic oxidation [71], and (high-)temperature stress [72] on various stabilizers was examined (see Table 3(c)). Reaction pathways leading to the observed degradation products were much more complex and were highly dependent on the simulated environment.…”

Section: Degradation Products Of Stabilizers After Other Degradative mentioning

confidence: 99%

Analysis of polyolefin stabilizers and their degradation products

Reingruber

Buchberger

2010

J of Separation Science

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Polymeric materials are complex samples, as they contain various groups of additives, compounding ingredients, and fillers. An important group of additives are stabilizers. Efficient stabilization is essential especially for polypropylene, as it is sensitive to oxidation and radical attack due to the numerous tertiary carbon atoms in its structure. How long a polymer will be sufficiently stabilized can be deduced from the contained amount of intact stabilizer. Different approaches for the analysis of stabilizers in polyolefins are available, which include sample preparation with subsequent chromatographic separation as well as direct analysis techniques. In round-robin tests, stabilizer concentrations obtained varied strongly. This shows the demand for reliable and robust methods. Stabilizers get consumed while protecting the polymer and are then present as degradation products. They were observed while quantifying intact stabilizers, in migration studies, and - if volatile - in emission studies of polymers. Furthermore, e.g. interactions with other polymer ingredients or irradiation degraded stabilizers. The identification of degradation products provides a better insight into the reactions associated with stabilization. Their quantitation makes it possible to deduce the original level of stabilization. Furthermore, polymer ingredients degrading stabilizers can be identified. Knowledge on these interactions contributes significantly to improved polymer stabilization.

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Section: Degradation Products Of Stabilizers After Other Degradative mentioning

confidence: 99%

Analysis of polyolefin stabilizers and their degradation products

Reingruber

Buchberger

2010

J of Separation Science

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“…However, in contrast to the frequent reports of their occurrence in the environment, there is very limited information in the literature on the reaction pathways. There are a few reports on the free radical oxidation reactions with phenolic BZTs but the mechanistic information of the degradation steps is not fully understood and there are different views on whether the phenolic benzotriazoles behave in the same way as hindered phenolic antioxidants …”

Section: Introductionmentioning

confidence: 99%

Electrochemical Oxidation of the Phenolic Benzotriazoles UV‐234 and UV‐327 in Organic Solvents

Chan

Webster

2018

ChemElectroChem

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The electrochemical behavior of selected phenolic benzotriazoles (BZTs), namely 2‐(2H‐benzotriazol‐2‐yl)‐4,6‐bis(1‐methyl‐1‐phenylethyl)phenol and 2,4‐di‐tert‐butyl‐6‐(5‐chlorobenzotriazol‐2‐yl)phenol (commercial names UV234 and UV327, respectively) were examined with cyclic voltammetry (CV) and controlled potential electrolysis (CPE) in acetonitrile and dichloromethane solutions. CV indicated that both phenolic BZTs undergo a chemically irreversible oxidation process at approximately Ep°x=+1.0 V vs. Fc/Fc+ (where Ep°x is the anodic peak potential and Fc=ferrocene) to form compounds that cannot be electrochemically converted back to the starting material on the voltammetric timescale. In basic conditions, cyclic voltammetry experiments indicated that the corresponding phenolates (prepared by reacting the phenols with equiv. mols of n‐Bu4NOH) were oxidized at Ep°x∼−0.2 V vs. Fc/Fc+ via a one‐electron diffusion controlled process with anodic (ip°x) to cathodic (ipred) peak current ratios (ip°x/ipred)≫1, suggesting that the produced phenoxyl radicals decomposed rapidly via a chemical step. However, electron paramagnetic resonance (EPR) experiments performed on the bulk electrolyzed solutions of the phenolates after one‐electron bulk oxidation indicated long lifetimes of the UV234. and UV327. phenoxyl radicals. Therefore, the long timescale CPE and spectroscopic (UV‐vis and EPR) studies provided good evidence of a reversible dimerization mechanism between the phenoxyl radicals, which explained the apparent discrepancy with the short timescale CV experiments.

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“…UV absorber has been found to be depleted from the surface of naturally weathered polycarbonate (S), and the photostability of several UV absorbers has been studied by flash photolysis and by exposure to mercury arc lamps (9). Recently, the photodegradation of benzotriazole absorbers has been studied under conditions where leaching could be ruled out (10) and in UV-cured coating systems (11)(12)(13). Since the findings have been fragmentary, and the kinetics of the process ill-defined, we have recently undertaken a systematic study of UV absorber stability in several matrices with an emphasis on coatings.…”

Section: Introductionmentioning

confidence: 99%

Photodegradation of UV absorbers: Kinetics and structural effects

Pickett¹,

Moore²

1995

Angew. Makromol. Chem.

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When poly(methy1 methacrylate) films containing UV absorbers are exposed to UY light, the absorbers undergo photodegradation resulting in loss of absorbance. If the data extend for less than one half-life, both zero and first order kinetic treatment give fairly linear fits, but the rate constants so derived are dependent on the initial absorbance of the films. When the zero order rate. constants ae corrected to account for the higher rate of degradation near the surface compared with the bulk that occurs in highly absorbing films, consistent "infinite absorption" zero order rate constants are derived. The inhomogeneous degradation is due to only the highiy absorbed, higher energy light contributing significantly to the degradation. For the benzophenone and benzotriazole classes of absorber, at least 65% of the degradation is due to light with wavelengths < 350 nm. Structural variations generally caused only small differences in the rates of degradation of these classes of absorbers unless the substitutions disrupted the intramolecular hydrogen bonds that are critical for stability. If the hydrogen bond is weakened, the absorber is less stable.

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Permanence of polymer stabilizers in hostile environments

Cited by 26 publications

References 10 publications

Analysis of polyolefin stabilizers and their degradation products

Analysis of polyolefin stabilizers and their degradation products

Electrochemical Oxidation of the Phenolic Benzotriazoles UV‐234 and UV‐327 in Organic Solvents

Photodegradation of UV absorbers: Kinetics and structural effects

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