Temperature dependent degradation of phenolic stabilizers and ageing behaviour of PP-R micro-specimen

This paper deals with the hot air ageing behaviour of a polypropylene random copolymer (PP-R) model material in wide temperature range from 65 to 135°C. The PP-R grade was stabilized blend phenolic antioxidants Irganox 1330 and 1010. To avoid diffusion-limited oxidation effects, micro-specimen thickness 100 µm were investigated. As main indicator phenol index evaluated FTIR-spectra transmittance mode. functional groups associated shift absorption peak by 18 35 cm-1 single- dual-oxidized antioxidant 1330. implemented FTIR evaluation approach validated high-pressure liquid chromatography hyphenated mass spectroscopy ultraviolet detection. Gaussian fitting triple IR-peak confirmed dependent differences degradation pathways antioxidants. decay obtained endurance time exhibited bilinear Arrhenius like transition at 110°C, which agreement onset melting small crystal lamellae. activation energy values 94 32 kJ mol-1 above below temperature, respectively.