Study of the response of phenol compounds exposed to thermal neutrons beams for Electron Paramagnetic Resonance dosimetry

Radical processes initiated by ionizing radiation in PEEK and their macroscopic consequences

“…Another possible pathway of radical processes is homolytic cleavage of C―O bond of ether groups which leads to the production of phenyl radical (Ph • ) and phenoxyl radicals (PhO • ) . The second radical is relatively stable in some systems, especially when the electron donor groups are located at the para and ortho positions of the aromatic ring . It is well known that when three butoxyl groups are present in these positions, then the radical achieves high stability.…”

“…[18][19][20] The second radical is relatively stable in some systems, especially when the electron donor groups are located at the para and ortho positions of the aromatic ring. [21][22][23] It is well known that when three butoxyl groups are present in these positions, then the radical achieves high stability. In the PEEK structure -Ph-Ogroup might be considered as one of such substituents.…”

“…The g-factor values are similar to those found in other systems (g 1 = 2.0028, g 2 = 2.0084, g 3 = 2.036). 25 Above 200 K PEEK shows low temperature relaxation (γ-relaxation) 9,22 related to the local conformational movements of aromatic rings in glassy state. After irradiation under oxidative conditions, the intensity of γ-relaxation decreases significantly at a dose of 8 MGy.…”

ESR dosimeter material properties of phenols compound exposed to radiotherapeutic electron beams

“…1): As it is visible, the OH of the phenol is protected by ramified alkyl chains, furthermore, the phenol ring is linked also to a long linear chain. Phenols are compounds possessing a benzene ring attached to a OH group and the irradiation produces a stable phenoxy radical [65].…”

“…Recently, the ESR features of some IRGANOX Ò 1076 phenols compounds (IUPAC name octadecyl 3-(3,5-ditert-butyl-4-hydroxy phenyl) propanoate) have been analyzed and promising properties have been found such as high efficiency of radiation-matter energy transfer and radical stability at room temperature for irradiation with photons and neutrons in both pellet and film shape [64][65][66][67].…”