Identification of thermal degradation products of polymers by capillary gas chromatography

Samples of polyethylene, polypropylene, polystyrene and five styrene copolymers were thermally degraded in a quartz tubular reactor at 5100e in an inert atmosphere. The degradation products were separated on-line on capillary coltmlS coated with squalane, OV-17 and SE-30 as stationary phases. The chromatographic retention data of the degradation products of the plastics studied were measured. Average values of the retention indices and standard deviations were calculated. The precision and accuracy of the indices obtained were found to be satisfactory only when known degradation products were taken as internal reference compounds. It is shown that the pyrolysis products of polyethylene and polypropylene can be identified reliably by only using the retention indices. To identify the degradation products of polystyrene and its copolymers, combined capillary gas chromatography - mass spectrometry had to be used, enabling the identification of some compounds among the pyrolysis products which have not yet been reported. Results of the quantitative analyses of the degradation products of the styrene (co)polymers are included.