Classification of polymers by determining of C1:C2:CN:H:N:O ratios by laser-induced plasma spectroscopy (LIPS)

In the recycling of post-consumer plastic waste there is a pressing need for rapid, on-line or at-line measurement technologies for simple identification of materials. The goal of this work was instant identification of post-consumer plastics by laser-induced plasma spectrometry (LIPS). These polymers are often polyethylene terephthalate (PET), polyolefins (polyethylene and polypropylene), poly(vinyl chloride) (PVC) and polystyrene (PS). A new approach for the determination of major elemental ratios in organic compounds such as polymers by using laser-induced plasma spectroscopy (LIPS) was investigated. In previous works, we have shown that simple statistical correlation methods, such as linear and rank correlations, can be successfully applied for identification of these materials. The C2 Swan system (516 nm), the CN band (388 nm), the carbon (247.9 nm), hydrogen (656.3 nm), oxygen (777.2 nm) and nitrogen (746.8 nm) emission intensity ratios were used to identify the plastics. The most important ratios were C2/C1 and H/C1.