Investigation of fluorescence spectra of various types of plastics for the purpose of sorting and further processing

Abstract

Excitation-emission matrices of various plastic package samples were studied. A tuneable 210-310 nm laser was used as an excitation source. The samples of polyethylene terephthalate, polypropylene, and high-density polyethylene of various colour and transparency showed multipeak wideband fluorescence spectra dependent on the excitation wavelength. Principal component analysis demonstrated that the excitation-emission matrices of most samples are well described by two principal components, individual for their types and colorant additives. Despite complex structure of the excitation-emission matrices of different types of the plastic, appropriate linear combinations of the principal components allowed finding a characteristic component for each of them.