Formation of free radicals in photoirradiated cellulose. I. Effect of wavelength

Hon, Nyok‐Sai

doi:10.1002/pol.1975.170130607

Cited by 54 publications

(18 citation statements)

References 34 publications

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“…Hon 964) investigated in detail the effect of wavelength for the formation of free radicals in photo-irradiated cellulose. No radicals were detected by ESR recordings when cellulose was irradiated with light of wavelength longer than 3300-3400 A.…”

Section: Esr Study Of Degradation Processes In Polymersmentioning

confidence: 99%

ESR Spectroscopy in Polymer Research

Rånby¹,

Rabek²

1977

Polymers Properties and Applications

295

118

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Section: Esr Study Of Degradation Processes In Polymersmentioning

confidence: 99%

ESR Spectroscopy in Polymer Research

Rånby¹,

Rabek²

1977

Polymers Properties and Applications

295

118

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“…Ref. 24). A comparison with previous investigations 25 indicated only some obvious differences in experimental spectra recorded at 77 K (Fig.…”

Section: Cellulosementioning

confidence: 77%

Electron spin resonance study of radicals generated in cellulose/N‐methylmorpholine solutions after flash photolysis at 77 K

Konkin

Wendler

Roth

et al. 2006

Magnetic Reson in Chemistry

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The processes of radical formation in N-methylmorpholine-N-oxide monohydrate (NMMO) and cellulose/NMMO solutions were studied by ESR at 77 K under high-power UV (lambda = 248 nm) excimer laser flash photolysis. Radicals mainly generated were attributed to the nitroxide type radicals -CH2-NO*-CH2- and -CH2-NO*-CH3 at the first step and methyl *CH3 and formyl *CHO radicals at the second step of the photoreaction. Kinetic studies of these radicals revealed that formation and recombination rates of the radicals depend on the cellulose concentration in cellulose/NMMO solutions and the concentration of additional ingredients, e.g. Fe(II) and propyl gallate. Even at frozen state temperature, acceleration or quenching of radical reaction processes was found. The proposed scheme of UV light-induced NMMO degradation during irradiation based on ESR data correlates well with independently obtained results based on high-performance liquid chromatography (HPLC). The analysis of degradation products by HPLC, e.g. aminoethanol and acetaldehyde, supports the assumption concerning a radical-initiated ring opening of NMMO.

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“…In addition, other cellulose degradation studies have observed an absorbance peak at 260 nm as a result of ultraviolet photolytic degradation (Yatagai and Zeronian 1994), enzymatic hydrolysis (Patel et al 1993), and acid hydrolysis (Kalinina et al 2001). This peak was assigned to a weak chromophore associated with acetal groups, which form the linkages between glucose residues in cellulose (Hon 1975). We determined that mechanical disruption of bacterial cellulose released small soluble cellulose fragments which absorb at 260 nm.…”

Section: Characterization Of Oxidized Compositementioning

confidence: 93%

A resorbable calcium-deficient hydroxyapatite hydrogel composite for osseous regeneration

et al. 2009

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It was previously discovered that the unique structure and chemistry of bacterial cellulose (BC) permits the formation of calcium-deficient hydroxyapatite (CdHAP) nanocrystallites under aqueous conditions at ambient pH and temperature.In this study, BC was chemically modified via a limited periodate oxidation reaction to render the composite degradable and thus more suitable for bone regeneration. While native BC does not degrade in mammalian systems, periodate oxidation yields dialdehyde cellulose which breaks down at physiological pH. The composite was characterized by tensile testing, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. X-ray diffraction showed that oxidized BC retains its structure and could biomimetically form CdHAP. Degradation behavior was analyzed by incubating the samples in simulated physiological fluid (pH 7.4) at 37°C under static and dynamic conditions. The oxidized BC and oxidized BCCdHAP composites both lost significant mass after exposure to the simulated physiological environment. Examination of the incubation solutions by UV-Vis spectrophotometric analysis demonstrated that, while native BC released only small amounts of soluble cellulose fragments, oxidized cellulose releases carbonyl containing degradation products as well as soluble cellulose fragments. By entrapping CdHAP in a degradable hydrogel carrier, this composite should elicit bone regeneration then resorb over time to be replaced by new osseous tissue.

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Formation of free radicals in photoirradiated cellulose. I. Effect of wavelength

Cited by 54 publications

References 34 publications

ESR Spectroscopy in Polymer Research

ESR Spectroscopy in Polymer Research

Electron spin resonance study of radicals generated in cellulose/N‐methylmorpholine solutions after flash photolysis at 77 K

A resorbable calcium-deficient hydroxyapatite hydrogel composite for osseous regeneration

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