Fast identification of plastics in recycling processes

Correct identification and segregation of plastics into well-defined material groups is of major importance in the recycling of polymer wastes. Manual sorting and segregation techniques based on the differences in physical properties are expensive and still fail to ensure the sufficiently high purity of the recyclate. The Western countries (mostly Germany) are introducing spectroscopic analytical methods that, basing on different polymer's chemical structures, enable polymer wastes (preseparated from other municipal wastes) to be identified quickly and correctly, regardless of their color, degree of contamination and moisture content. Radiography (X-ray absorption spectroscopy and X-ray fluorescence) and IR (NIR, MIR) methods were found to be industrially useful for sorting PE, PP, PVC, PET and PS bottles, "electrotechnical scrap" and old-car plastic wastes. Other techniques, e.g., thermooptical, laser-induced emission spectral analysis, sliding spark spectrocopy, etc., are at the test stage.