Pyrolysis-gas chromatography/mass spectrometry to identification of the solid waste characteristic of imported polyamide recycled plastics

Abstract

An analytical method for the determination of content of PA66 in PA6/PA66 blends by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) with silica (SiO2) as dispersant was established. After the sample was frozen and crushed into powder, silica was used as a solid dispersant mix with the sample, and the mixtures was injected. At 600°C cracking temperature, the corresponding cracking chromatogram was obtained, and the characteristic of PA66 on the cracking chromatogram of PA6/PA66 blend, the cyclopentanone, was selected as the quantitative peak to calculate the mass of PA66 in the PA6/PA66 blend. The content of PA66 in the dispersion was in the range of 0.50 g/kg ~ 100 g/kg, and the results had a good linear relationship. The detection limit of the PA66 was 0.50 g/kg (the corresponding PA66:PA6 ratio was 0.5:99.5). The PA6/PA66 samples with known mixing ratio were measured, and the recovery of the results was 95.7%~102.1%, and the relative standard deviation(RSD) was 1.6%~5.9% (n=3). It can accurately determine the content of PA66 in PA6/PA66 blends, and provide technical support for the attribute identification of related imported recycled plastic solid wastes.