Analytical methods recycled plastics

The manual sorting method is labor intensive and requires operators to monitor an assembly line and sort out clear plastic bottles (PET) from the milk containers (HDPE) and colored plastic containers (LDPE, PP, PVC). The automated method can employ one of several analytical techniques, including X-ray fluorescence, mass spectroscopy, Fourier Transform Near Infrared (FT-NIR) spectroscopy, Fourier Transform Medium Infrared (FTIR) spectroscopy, or tribo-electric analysis, on the recycled plastic materials. The state of Rhode Island has a single stream process to sort out the recycled materials with optical sorting technology. The recycled materials include cardboard, paper, glass, metal, and plastics (Rhode Island 2013). 

Additives can add problems to recycling of plastics, but they can also be one of the means of identification, which might simplify the process. While analytical methods such as NIR and XRF are useful in recycling of domestic waste, LIBS finds application in case of thermoplasts (ABS, PP, PPO)... 

An overview of fast identification of plastics in recycling processes by means of spectroscopic analytical methods has recently appeared [150]. While there have been some promising results in identification and separation of mixed plastics packaging waste, there is still much work to be done in the more complex technical and engineering compounds [158],... 

Similarly, the increasing efforts in recent years to recycle used plastics and plastics waste involve a number of analytical problems. Plastics waste containing a mixture of plastics can often be sorted using simple methods to identify the different plastics. It is stUl difficult, but possible, however, to automatically identify the different plastics and to sort them at the same... 

In order to consider effective strategies for the recovery and reuse of plastics recyclates, a quantitative method is described for the characterisation of polyester-based moulding compounds. Analytical procedures are described for the quantification of fibre, filler and fire retardant contents in polyester moulding compounds containing calcium carbonate filler, glass fibre reinforcement, and aluminium hydroxide flame retardant. 3 refs. 

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