Polyolefin branching antioxidants

Polyolefins such as polyethylene and polypropylene contain only C—C and C—H bonds and may be considered as high molecular weight paraffins. Like the simpler paraffins they are somewhat inert and their major chemical reaction is substitution, e.g. halogenation. In addition the branched polyethylenes and the higher polyolefins contain tertiary carbon atoms which are reactive sites for oxidation. Because of this it is necessary to add antioxidants to stabilise the polymers against oxidation Some polyolefins may be cross-linked by peroxides. 

A brief review is presented on techniques for the analysis of polyolefins and additives in polyolefins. Techniques considered include high-temperature GPC combined with FTIR spectroscopy for the analysis of chemical composition as a function of molar mass, crystallisation fiactionation for the analysis of short-chain branching in LLDPE and of polyolefin blends and pyrolysis-gas chromatography-mass spectrometry for the determination of additives, such as antioxidants, in polyolefins. 13 refs. (3rd Annual UNESCO School lUPAC Conference on Macromolecules and Materials Science, Stellenbosch, South Africa, 2000)... 

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