Effect of the Phenolic Antioxidants on the Structure of Gamma-Irradiated Model Polyethylene

ANDREUCETTI, N A; SARMORIA, C; CURZIO, O A; VALLÉS, E M

RADIATION PHYSICS AND CHEMISTRY (OXFORD)

Elsevier Science

Lugar: Oxford; Año: 1998 vol. 52 p. 177 - 182

0969-806X

High energy radiation has been successfully employed to modify the chemical structure of commercial polymers. It induces at least two types of reaction in polyethylene: crosslinking and chain scission. In addition the efficiency of the radio-induced reactions can be affected by the presence of antioxidants. The purpose of this work is to study the effect of the irradiation on a model polyethylene containing a phenolic type antioxidant. Samples containing 0.1% and 1% by weight of lrganox 1010 (Ciba-Geigy) were irradiated under vacuum at room temperature with different doses of gamma rays from a 60Co source. Changes in structure and the average molecular weight were followed by gel permeation chromatography and low angle laser light scattering. The critical doses for gelation were determined as a function of the antioxidant concentration. Theoretical calculations to predict the evolution of molecular structure with extent of radiation were performed using a probability model. The agreement between the calculated and the measured molecular weights is very good.