Recycling of plastics: Automatic identification of polymers by spectroscopic methods

In the recycling process of polymers, at least two steps might require an automatic identification tool: the sorting of the plastics, and the qualification of the regenerated product. We have tested the efficiencies of reflectance FTMIR and FT Raman with respect to these identification applications. Although it was possible with both techniques to recognize most usual polymers, severe limitations of FTMIR were evidenced such as a high sensitivity to the surface state, and a weak (noisy) reflectance signal for CH bonds. On the other hand FT Raman proved to be a rapid ( ∼ 1 s per object) and highly selective method, giving information even on the mineral fillers present in plastics.