Sorting Plastic Resins Using NIR Spectroscopy

Plastic resins are composed of a range of polymer types. Similarities in the size and shape of the resins make them difficult to distinguish by sight alone. In this application note, near infrared (NIR) spectroscopy is used to sort colored resins composed of different polymers. Diffuse reflection measurements are made in the NIR region to capture distinct spectral differences resulting from the unique polymer compositions, while avoiding the detection of spectral differences arising from resin color.