On the mechanism of photo- and photo-oxidative-degradation of acetyl cellulose

Koz'mina, O.P.; Dubyaga, V.P.; Belyakov, V.K.; Zaichukova, N.A.

doi:10.1016/s0014-3057(69)80038-8

Cited by 8 publications

(3 citation statements)

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“… 58 The two sharp peaks at 128 and 159 °C might be due to, for example, formation of oligosaccharide units, acetylated glucose units, or destruction of pyranose rings. 22 The aging in simulated sea water under UV irradiation (CA + CD-SW-UV) instead increased the T g temperature, which can be connected to the deacetylation and partial regeneration of the cellulose structure. 59 , 60 Without UV treatment no significant changes were observed.…”

Section: Resultsmentioning

confidence: 99%

“… 19 The photodegradation of cellulose, CA, and cellulose triacetate have been investigated using irradiation at a wavelength of 275 nm. 20 − 22 Deacetylation was not apparent in the case of cellulose triacetate, but chain scission, oxidation, and cross-linking were observed in the presence of oxygen. The absorption maximum for CA is at ∼260 nm, while the cutoff for sunlight reaching earth is at 300 nm.…”

Section: Introductionmentioning

confidence: 99%

“…Exposure of ultraviolet light (UV light) from the sun has the ability to physically break down many plastics into small pieces by generating free radical species and follow-up oxidative reactions leading to release of CO 2 and other small molecules . The photodegradation of cellulose, CA, and cellulose triacetate have been investigated using irradiation at a wavelength of 275 nm. − Deacetylation was not apparent in the case of cellulose triacetate, but chain scission, oxidation, and cross-linking were observed in the presence of oxygen. The absorption maximum for CA is at ∼260 nm, while the cutoff for sunlight reaching earth is at 300 nm.…”

Section: Introductionmentioning

confidence: 99%

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Carbon Dot-Triggered Photocatalytic Degradation of Cellulose Acetate

2021

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Chemical modification of biopolymers, before use in thermoplastic applications, can reduce the susceptibility to open environment degradation. We demonstrate carbon dots (CDs) as green photocatalytic triggers that can render the common cellulose derivative, cellulose acetate (CA), degradable under open environment relevant conditions. CD-modified cellulose acetate (CA + CD) films were subjected to UV-A irradiation in air and simulated sea water, and the degradation process was mapped by multiple spectroscopic, chromatographic, and microscopy techniques. The addition of CDs effectively catalyzed the deacetylation reaction, the bottleneck preventing biodegradation of CA. The photocatalytically activated degradation process led to significant weight loss, release of small molecules, and regeneration of cellulose fibers. The weight loss of CA + CD after 30 days of UV-A irradiation in air or simulated sea water was 53 and 43%, respectively, while the corresponding values for plain CA films were 12 and 4%. At the same time the weight average molar mass of CA + CD decreased from 62,000 to 11,000 g/mol and 15,000 g/mol during UV-A irradiation in air and simulated sea water, respectively, and the degree of substitution (DS) decreased from 2.2 to 1.6 both in air and in water. The aging in water alone did not affect the weight average molar mass, but the DS was decreased to 1.9. Control experiments confirmed the generation of hydrogen peroxide when aqueous CD dispersion was subjected to UV-A irradiation, indicating a free radical mechanism. These results are promising for the development of products, such as mulching films, with photocatalytically triggered environmental degradation processes.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Carbon Dot-Triggered Photocatalytic Degradation of Cellulose Acetate

2021

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Photodegradation of cellulose acetate fibers

Hon

1977

J. Polym. Sci. Polym. Chem. Ed.

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The photodegradation of cellulose acetate fibers by ultraviolet light in vacuo at 77°K and at ambient temperature was studied. Three kinds of light sources with different wavelengths between 2353 and 6000 Å were employed. ESR studies at 77°K show that several kinds of free radicals are produced from cellulose diacetate (CDA) and cellulose triacetate (CTA) fibers when irradiated with light of wavelength shorter than 2800 Å. Among these methyl radicals formed decayed within 210 min at 77°K. When the temperature was raised above 77°K, radical transformation occurred at 87°K and most of the free radicals decayed at 193°K, whereas the cellulosic radicals were stable at this and even at higher temperatures. Ultraviolet spectroscopy studies revealed that the main chromophores are the carbonyl function of the acetyl group and acetal groups in the polymer. The photodegradation of the polymers at ambient temperature resulted in the formation of gaseous products (mainly CO, CO2, and CH4), together with the loss of bound acetic acid content and sample weight. Decreases in viscosity and reduction of tensile strength and elongation were also observed in the irradiated samples, revealing that the overt effects of ultraviolet light on cellulose acetate fibers are interpreted in terms of free‐radical reactions ultimately leading to main‐chain and side‐group scissions, unsaturation, and the formation of small molecule fragments. Among these, main‐chain scission took place predominantly in CDA fiber and side‐group scission in CTA fiber. The mechanism of the fundamental photochemical degradation processes of cellulose acetate fibers is elucidated.

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Distribution spatiale des dommages produits par les ions Kr (1 MeV/amu) et Cl (1 MeV/amu) dans le triacétate de cellulose

Moliton

Boutinaud

Decossas

et al. 1982

J. Polym. Sci. Polym. Phys. Ed.

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Our earlier results on ασ and heavy‐ion‐radiation damage in cellulose triacetate (CTA) are compared with those of previous authors on UV‐and γ‐radiation damage in the same material. Thus the common effects of these different methods of irradiation can be distinguished from those characteristic of the radiation employed. With heavy‐ion radiation the production of stable radicals is accompanied by C—O cleavage. In the case of 3684Kr (1 MeV/amu) ions, the number of free radicals produced is investigated, without distinguishing the species, by using the scavenger technique in the solid phase, combined with UV spectroscopy. On the other hand, C—O cleavage is observed by IR spectroscopy, with its inherent selectivity. A statistical study shows that the experimental curves representative of the evolution of the optical transmittance ratio before and after irradiation L(N) versus the ion fluence N are of exponential type: where β is a parameter related to the volume damaged by a single ion and, therefore, to the latent track size. The latter is approximated by a cylinder whose height is equal to the range of the ion. For 3684Kr8+ (1.1 MeV/amu) the track length is 21 μ. For each type, damages are localized within a radius of 250 Å for free‐radical yields, 148 Å for cellulosic chain cleavages, 108 Å for deacetylation, and 100 Å for opening of pyrannosic rings. The track length is 14 μ for 1735Cl6+ (1 MeV/amu), while the radius of the cylinder in which free radicals are produced is only 80 Å.

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On the mechanism of photo- and photo-oxidative-degradation of acetyl cellulose

Cited by 8 publications

References 4 publications

Carbon Dot-Triggered Photocatalytic Degradation of Cellulose Acetate

Carbon Dot-Triggered Photocatalytic Degradation of Cellulose Acetate

Photodegradation of cellulose acetate fibers

Distribution spatiale des dommages produits par les ions Kr (1 MeV/amu) et Cl (1 MeV/amu) dans le triacétate de cellulose

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