Stabilisation of LDPE cross-linked in the presence of peroxides III. Mass spectrometric study of chemical changes taking place in the n-octadecane-dicumyl peroxide-Irganox 1081 system

An attempt was made to identify the products of the reaction between dicumy l peroxide and Irganox 1081, carried out in n-octadecane (saturated hydroca rbon), in conditions of fast decomposition of the peroxide (180 degreesC, 5 min). Mass spectrometry (MS) was employed to find mit values of molecular and fragment ions in analyses of the components (n-octadecane, dicumyl pero xide, Irganox 1081) and of the following systems: n-octadecane-dicumyl pero xide, n-octadecane-Irganox 1081 and n-octadecane-dicumyl peroxide-Irganox 1 081, after holding them at a temperature of 180 degreesC for 5 min. The ten dency of sulphur in Irganox 1081 to oxidise, specifically in the presence o f dicumyl peroxide, was confirmed. Hypothetical formulae of Irganox 1081 de rivatives, resulting from the reaction between Irganox and the peroxide, we re proposed. (C) 2000 Elsevier Science Ltd. All rights reserved.