scholarly journals Trapped radical behavior of electron beam irradiated polytetrafluoroethylene fine powder at various temperatures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Akihiro Oshima ◽  
Hiroto Horiuchi ◽  
Atsushi Nakamura ◽  
Shun Kobayashi ◽  
Ayana Terui ◽  
...  
Keyword(s):  
Electron Beam ◽  
Main Chain ◽  
Absorbed Dose ◽  
Fine Powder ◽  
Electron Attachment ◽  
Nitrogen Atmosphere ◽  
Irradiation Temperature ◽  
Spin Resonance ◽  
G Value ◽  
Chain Type

AbstractPolytetrafluoroethylene (PTFE) fine powder with 93% crystallinity was irradiated by an electron beam (EB) at various temperatures under a nitrogen atmosphere. Trapped free radicals in PTFE were studied using electron spin resonance (ESR) spectroscopy. The observed spectra of the samples exposed to air after irradiation at various temperatures showed asymmetrical signals, which are middle-chain type peroxide macroradicals derived from fluoroalkyl radicals. The radical yields at each irradiation temperature increased with increasing absorbed dose, and eventually saturated. The higher irradiation temperature resulted in higher radical yields when compared at the same exposed dose. Furthermore, the G-value of the radicals (G(R·)) increases with increasing irradiation temperatures corresponding to each relaxation and transition temperature. It is concluded that the chain reaction by the fluorine extraction from the main chain due to the end-chain radical generated via β-scission after dissociative electron attachment (DEA) is enhanced by the synergistic effect of heat and radiation.

Main-Chain-Type 8-Quinolinol Polymers:  Synthesis, Optical Properties, and Complex Formation with Metals

2008 ◽  
Vol 41 (5) ◽  
pp. 1654-1662 ◽  
Author(s):  
Takayuki Iijima ◽  
Shin-ichi Kuroda ◽  
Takakazu Yamamoto
Keyword(s):  
Optical Properties ◽  
Complex Formation ◽  
Main Chain ◽  
Chain Type

The Influence of Irradiation Temperature on U.V. Induced Defect Creation in Dry Silica

1985 ◽  
Vol 61 ◽  
Author(s):  
R. A. B. Devine ◽  
C. Fiori ◽  
J. Robertson
Keyword(s):  
Oxygen Vacancy ◽  
Peroxy Radical ◽  
Irradiation Temperature ◽  
Threshold Temperature ◽  
Peroxy Radicals ◽  
Oxygen Hole ◽  
Spin Resonance ◽  
Dependent Growth ◽  
Dose Dependent ◽  
Annealing Curve

ABSTRACTElectron spin resonance measurements have been carried out on samples of Suprasil Wl (dry silica) subjected to ultraviolet laser radiation (λ = 248 nm, E = 5 eV/photon). Studies have been made for fixed irradiation temperature (room) variable accumulated ultraviolet dose and fixed accumulated dose (3000 J/cm2) at various irradiation temperatures in the range 110 K to 335 K. Three principal defect centers are observed. Non-bridging oxygen hole centers are created at all temperatures in the range studied with slightly higher efficiency at room temperature (ration 300 K/150 K ∼ 2.5). Comparison of the dose dependent growth curve of the 4.8 eV absorption and its isochronal annealing curve with those for the oxygen hole center clearly identify the origin of the absorption band with this defect. A threshold temperature ∼ 200 K is found for oxygen vacancy creation consistent with results on single crystalline quartz. Post irradiation annealing at 593 K eliminates the vacancy centers and the peroxy radical resonance appears. Its growth as a function of accumulated ultraviolet dose and irradiation temperature supports the hypothesis that peroxy radicals form by the trapping of diffusing, molecular oxygen at the oxygen vacancy center.

Crosslinked main-chain-type polybenzoxazine coatings for corrosion protection of mild steel

2017 ◽  
Vol 14 (4) ◽  
pp. 937-944 ◽  
Author(s):  
Xin Lu ◽  
Yan Liu ◽  
Wenfei Zhang ◽  
Xueying Zhang ◽  
Changlu Zhou ◽  
...  
Keyword(s):  
Mild Steel ◽  
Corrosion Protection ◽  
Main Chain ◽  
Chain Type

Effects of Electron Beam on Structure and Physical Properties of Natural Colorless Topaz

2015 ◽  
Vol 1125 ◽  
pp. 60-63
Author(s):  
Chutharat Paikaew ◽  
Juthamas Inthanont ◽  
Adisak Punyanut ◽  
Ekachai Hoonnivathana ◽  
Pichet Limsuwan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Beam ◽  
Physical Properties ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spin Resonance ◽  
Function Group ◽  
And Function ◽  
Beam Dose

The purpose of this research was to investigate physical properties, configuration and color of topaz. Topazes were irradiated with electron beam linear accelerator at different dose from 40 to 180 MGy. The color of topaz was analyzed by UV-vis and it was shown that the color of topaz was becoming strong color with increased electron beam dose. Crystal structure and function group of topaz were characterized by X- ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results showed that the topaz has orthorhombic structure and no other crystalline. After irradiated, topaz released OH indicating higher crystallinity of topaz and this was confirmed with the results of electron spin resonance (ESR). Electron beam dose response of topaz was investigated. ESR results showed that the Al3+ ion was substituted in Si4+ site and Ti3+ impurity in Al4+ site and this result corresponds to the results of FTIR. The experiment result indicated that electron beam could be making defect on crystal structure and color enhancement of topaz.

Effect of Al Powder Content on Performance of MgO-Al2O3 Composite at 1700°C under N2 Atmosphere

2016 ◽  
Vol 697 ◽  
pp. 337-340
Author(s):  
Shang Hao Tong ◽  
Yong Li ◽  
Yang Hong ◽  
Dan Dan Yue ◽  
Jia Jia Ma
Keyword(s):  
Fine Powder ◽  
Nitrogen Atmosphere ◽  
Mass Percent ◽  
Comprehensive Performance ◽  
Al Powder ◽  
Powder Content

Specimen was made with fused magnesia (the mass percent is 65%) as aggregates and Al fine powder, sintered magnesia, tabular alumina and α-Al2O3 fine powder as co-mixture powder (the mass percent is 35%) . Specimen were prepared in nitrogen atmosphere at 1700°C. The results indicate that the MgAlON was formed under the prevailing conditions. Al powder content has an important effect on properties of Al-MgO-Al2O3 composites. With the Al powder content increasing, the amounts of MgAlON increases. When the content of Al powder is 6%, the MgAlON composite has the best comprehensive performance.

Facile photochemical synthesis of main-chain-type semifluorinated alternating copolymers catalyzed by conventional amines or halide salts

2021 ◽  
Author(s):  
Yuxue Wang ◽  
Kai Tu ◽  
Jiannan Cheng ◽  
Enjie He ◽  
Jinying Wang ◽  
...  
Keyword(s):  
Main Chain ◽  
Halogen Bond ◽  
Low Cost ◽  
Photochemical Synthesis ◽  
Alternating Copolymers ◽  
Halide Salts ◽  
Chain Type

In this work, we report a much simple and low-cost method to prepare main-chain-type semifluorinated alternating copolymers by the formation of halogen bond (XB) complex between α,ω-diiodoperfluoroalkanes and amines/halide salts....

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