The effect of transformation products of the antioxidant BHT on the initial stages of thermo- and photo-oxidation of LDPE

Abstract

The effect of individual transformation products of 2,6-di-tert-butyl-4-methylphenol (1, BHT), namely, 2,6-di-tert-butyl-4-hydroxy-2,5-cyclohexadienone (3), 2,6-di-tert-butyl-1,4-benzoquinone (4), and 3,5,3′,5′-tetra-tert-butylstilbenequinone (5), in the course of thermal- and photo-degradation of LDPE has been examined. Oxidative DSC studies combined with oxygen uptake measurements, IR spectroscopy data, and embrittlement tests proved to be sufficiently sensitive to detect differences in the stability of the above-mentioned samples. A comparative study revealed a pronounced stabilizing effect of 5 in LDPE thermooxidation at moderate temperatures (90-100°C). The stabilizing action of BHT is due in part at least to its coloured transformation product.