Radicals mediated magnetism in Ar plasma treated high-density polyethylene

Electron-spin resonance of high-density polyethylene treated by Ar plasma at 300 K was performed in X-band at temperatures from 2.1 K to 290 K. The observed spectra suggest presence of allyl radicals, whereas the central peak may be attributed to polyenyl radicals or dangled bonds. Pronounced narrow...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2018-05, Vol.454, p.185-189
Main Authors: Orendáč, M., Čižmár, E., Kažiková, V., Orendáčová, A., Řezníčková, A., Kolská, Z., Švorčík, V.
Format: Article
Language:English
Subjects:
Antiferromagnetism
Couplings
Density
Dimers
Electron spin
High density polyethylenes
Magnetism
Plasma physics
Polyethylene
Radicals
Spin resonance
Temperature
Temperature dependence
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Summary:Electron-spin resonance of high-density polyethylene treated by Ar plasma at 300 K was performed in X-band at temperatures from 2.1 K to 290 K. The observed spectra suggest presence of allyl radicals, whereas the central peak may be attributed to polyenyl radicals or dangled bonds. Pronounced narrowing of the resonance line observed above glassy temperature of polyethylene may be ascribed to thermally activated motional effect with the activation energy Ea/kB=160 K. The absence of strong exchange interactions is suggested by negligible exchange narrowing found at 2.1 K. The suggestion is supported by the analysis of the temperature dependence of the intensity at low temperatures, which is explicable assuming the coexistence of non-interacting radicals and S = 1/2 dimers with a distribution of antiferromagnetic couplings varying from 2 K to nominally 25 K.
ISSN:0304-8853
1873-4766
DOI:10.1016/j.jmmm.2018.01.087