FT-IR analysis and hyperspectral imaging applied to postconsumer plastics packaging characterization and sorting

Postconsumer plastics packaging waste represents one of the primary source of recovered polymers. One of the main problem now arising is thus the need to certify, in a fast (i.e., online) and reliable way, recovered plastics composition, as well as to assess polymers mixtures bulk characteristics, in order to partially, or totally, reuse them. This paper is addressed to verify the possibility offered by a new technique, hyperspectral imaging (HSI)-based, in order to perform a real-time online identification of polymers as resulting from a recycling process. This approach was specifically adopted to identify the presence of polyvinyl chloride (PVC) in the heavy fraction resulting from an industrial sink-float process. PVC detection is important because heavy fraction recovery is finalized to its further reutilization as solid recovered fuels. The presence of this polymer, in fact, for its chlorine content (i.e., dioxin production during combustion) negatively affects the thermal recovery of these products. This paper demonstrated as the proposed HIS-based approach, in the near-infrared range (1000-1700 nm), can be successfully utilized to setup real-time analytical/control strategies to perform a continuous monitoring of the composition of the different flow plastic waste streams resulting from industrial processing, with particular reference to PVC identification.