Resumen

SILVA, Pedro; ALBANO, Carmen  y  PERERA, Rosestela. Use of electron paramagnetic resonance to evaluate the behavior of free radicals in irradiated polyolefins. Rev. LatinAm. Metal. Mater. [online]. 2008, vol.28, n.2, pp.79-90. ISSN 0255-6952.

The Electron Paramagnetic Resonance (EPR) had its most important development at the end of World War II. It is a non destructive technique of characterization and is the technique used for excellence to detect and characterize free radicals. It is well known that the presence of free radicals in polymeric materials is responsible for the appearance of a variety of effects in the polymer chains. There are, fundamentally, two ways for the generation of free radicals in a polymeric chain: chemical methods and irradiation with electromagnetic waves of medium and high energy. Gamma and x-rays produce ionization in all solids. In insulators and polymers chemical reactions may be promoted, some of which cannot be induced by other means. These last methods have the advantage that they do not leave polluting agents into the polymer. EPR has been used to interpret quantitatively and qualitatively the free radicals generated by the irradiation of polymeric materials. EPR results from different polymers and polymeric blends irradiated with gamma irradiation at low dose rates will be presented in this article. The behavior of allyl, alkyl, peroxide and polyenyl radicals, among others, is studied using a decay model.

Palabras clave : Electron paramagnetic resonance (EPR); Gamma irradiation; Antioxidants; Polypropylene; Polyethylene.