Recycling has become an important subject in today's society due to the impact of waste on our environment and the loss of valuable recources. In the past, sorting of recyclable materials (e.g. paper, plastics and textiles) was mainly done by hand. Nowadays, NIR spectroscopy has become a standard in the recycling industry.
One of the most difficult materials to classify in a recycling waste stream is plastic. Reflection measurments employing near-infrared spectroscopy enable the classification of many of the most common polymers present in recycling waste streams. Each polymer has a distinctive fingerprint spectra which allows for the identification of recyclable plastics and the elimination of contaminants which can create downstream problems in the plastic extrusion process.
Modern large-scale recycling sorting systems are using NIR spectroscopy to rapidly and automatically identify different plastics and eliminate contaminants.