Degradation of γ-irradiated linear perfluoroalkanes at high dosage

Allayarov, S. R.; Konovalikhin, Sergey V.; Ol’khov, Yu. A.; Jackson, Virgil E.; Kispert, Lowell D.; Dixon, David A.; Ila, D.; Lappan, Uwe

doi:10.1016/j.jfluchem.2007.01.012

Cited by 45 publications

(12 citation statements)

References 28 publications

(43 reference statements)

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“…The values agreed well with those obtained in DFT calculations and were also consistent with data from EPR studies of fluorinated radicals in single crystals [68,69]. Simulations were not employed, however.…”

Section: Fluorinated Polymers the Anisotropicsupporting

confidence: 84%

Applications of EPR and ENDOR Spectrum Simulations in Radiation Research

Erickson

Lund

2014

Applications of EPR in Radiation Research

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Applications of EPR and ENDOR simulations of relevance in radiation research involving free radicals, radical pairs, triplet states and to less extent metal complexes are treated. Early fundamental work involving in situ radiolysis of liquids and stickplot analysis of spectra is reviewed, while single crystal analysis is only briefly discussed. The analysis of data obtained with continuous wave methods of species trapped in disordered solids, "powders" is emphasized. Simulations based on first and second order and exact theory are described and exemplified. Methods to obtain parameters for the dynamics of radicals in irradiated solids and for the simulation of spectra at microwave saturation are discussed. Procedures for the simulation of powder ENDOR spectra of radicals are described in detail, with special emphasis on the influence of nuclear quadrupole couplings due to nuclei with I ≥ 1. EPR and ENDOR simulation programs known to us are presented in an Appendix, including addresses for downloading when available.

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Section: Fluorinated Polymers the Anisotropicsupporting

confidence: 84%

Applications of EPR and ENDOR Spectrum Simulations in Radiation Research

Erickson

Lund

2014

Applications of EPR in Radiation Research

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“…The TMC of irradiated PTFE shows a completely amorphous topological structure consisting of amorphous and cluster portions (Table IV), instead of the amorphous‐crystalline structure of virgin PTFE (Table I). The nature of the changes in the block structure of PTFE and the development of amorphous structure on γ‐irradiation has been discussed in detail 14, 33, 34. The γ‐irradiation of the FVE/TFE copolymer (2.4 mol % of FVE) leads to the disappearance of the crystal portions the TMC of the irradiated copolymer show only amorphous and cluster regions (Table IV), essentially the same result as for pure PTFE.…”

Section: Resultsmentioning

confidence: 79%

“…However, the changes due to radiation could be quite different. γ‐irradiation of the PTFE macromolecule14, 33, 34 leads to loss of a fluorine atom by breaking a C‐F bond which leads to loss of crystallinity and, consequently, mechanical durability of the polymer. The larger volume of the OCF 2 CF 2 Cl functional group in FVE/TFE copolymers will break up the helical conformation of virgin PTFE chains which should affect the radiolysis and change the chemistry.…”

Section: Resultsmentioning

confidence: 99%

Emulsion copolymerization of tetrafluoroethylene with ω‐chlorotetrafluoroethyltrifluorovinyl ether and the synthesized copolymer properties

Allayarov

Ilyin²,

Ol’khov

et al. 2011

J of Applied Polymer Sci

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Emulsion copolymerization of ω‐chlorotetrafluoroethyltrifluorovinyl ether (Cl(CF2)2OCF = CF2 (FVE)) with tetrafluoroethylene (CF2 = CF2 (TFE)) was investigated at various monomer ratios. The copolymerization rate is below the rate of TFE homopolymerization and the copolymerization kinetics depends on the FVE content in the reaction medium. The copolymer composition is very similar if the FVE content in monomer mixture is ≤2.5 mol %. However, the percent amount of FVE in the copolymer, the copolymerization rate, and molecular mass of synthesized copolymers decrease noticeably with increase in the FVE content in the monomer mixture. The constants of copolymerization are r1= 2.8 (TFE) and r2 = 0.03 (FVE). The copolymer is a statistical polymer consisting of TFE blocks and individual FVE molecules between the blocks. The average molecular mass of copolymers is significantly less than that of the TFE homopolymer (PTFE) synthesized at the same conditions. The morphologies of PTFE and copolymer powders were investigated by thermomechanical analysis and are not similar. The copolymer has a completely amorphous diblock morphology depending on the FVE content. The introduction of FVE molecules into the copolymer macromolecules is accompanied by reduction of the crystalline portion of copolymer. If the FVE content in copolymer is ≥3.5 mol %, the copolymer macromolecules completely lose the ability to form crystalline portions as a result of their amorphicity. The introduction of up to 2.4 mol % FVE into the copolymer macromolecules yields a highly thermostable and meltable copolymer which can be processed by using the industrial processes used widely for thermoplastics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

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“…This is because gamma photon destroys the linear structure of the C C backbone of PTFE and induces disordered binding of the free radicals. 26 Figure 2B1,B2 shows the surface morphologies of the pristine and the irradiated PEEK, respectively. The locally distributed microparticles cluster defects are observed at the pristine PEEK surface.…”

Section: Mechanical and Tribological Propertiesmentioning

confidence: 99%

Comparative study on microstructure, mechanical, and tribological property of gamma‐irradiated polytetrafluoroethylene, polyetheretherketone, and polyimide polymers

Chai

Ning

Qiao

et al. 2021

Surface & Interface Analysis

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In this paper, three commercial polymers (polytetrafluoroethylene [PTFE], polyetheretherketone [PEEK], and polyimide [PI]) were irradiated by gamma rays in the ambient air. The changes in microstructure, mechanical, and tribological properties of these three polymers after irradiation were investigated comparatively. The results display that both the surface and internal structures of PTFE are degraded due to the irradiation chemical reaction, and the molecular chain scission at the surface is more severe than that at its internal as a result of the involvement of oxygen. The oxidative degradation also plays a dominant role in the PEEK surface, but the molecular chain crosslink is dominant in the PEEK internal. The top layer of PI also shows the characteristics of oxidative irradiation degradation, but its internal exhibits excellent irradiation resistance and no structure change occurs even at irradiation doses up to 20 MGy. The microhardness and scratch resistance of irradiated surfaces for all three polymers decrease but only the scratching damage mode of PTFE changes after irradiation. Friction experiments show that the friction coefficients of PTFE increase but that of PEEK decrease after irradiation. The wear rates on the irradiated surfaces of all three polymers increase compared with the unirradiated samples. Moreover, there is a depth gradient effect on the wear properties of both irradiated PTFE and PEEK polymers. The changes in wear rates of irradiated surfaces are consistent with the structural variations of all three polymers.

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Degradation of γ-irradiated linear perfluoroalkanes at high dosage

Cited by 45 publications

References 28 publications

Applications of EPR and ENDOR Spectrum Simulations in Radiation Research

Applications of EPR and ENDOR Spectrum Simulations in Radiation Research

Emulsion copolymerization of tetrafluoroethylene with ω‐chlorotetrafluoroethyltrifluorovinyl ether and the synthesized copolymer properties

Comparative study on microstructure, mechanical, and tribological property of gamma‐irradiated polytetrafluoroethylene, polyetheretherketone, and polyimide polymers

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