Near-infrared material sorting uses near-infrared light to be absorbed by the polymer molecule's doubling and combined frequency, and distinguishes the absorption spectrum of a specific functional group. It can effectively distinguish plastics of different materials, regardless of color and shape.
Near-infrared light refers to the part of the electromagnetic spectrum with a wavelength of 780-2526nm. The absorption of a certain band of light by the vibration of material molecules produces a light absorption spectrum that is different from other material molecules, and the material can be identified by this spectrum. The vibrations of most molecules in the near-infrared spectral region are low-energy electronic transitions, stretching and doubling of frequency and combined absorption of hydrogen-containing atomic groups (such as NH, OH, CH, SH, etc.). This information contains a wealth of features, which is enough to describe common The "fingerprint" of plastic.