A7.5 Identification of Possible RICs from Infra-red Spectra
Each type of plastic has groups of atoms and covalent bonds that help to identify which type it is.
So by looking for the appropriate frequencies associated with these bonds, some degree of categorisation is possible.
This is a very complex technology related to the way that different chemical bonds absorb infra red radiation. On a very basic level we can say that:
Types 
only have
and
bonds.
Type 
additionally has
bonds.
Type 
additionally has benzene rings.
However, much more sophisticated distinctions can be made which enable automated systems to sort large quantities of mixed plastic waste.
The different RIC categories can be sorted quickly and efficiently enabling the processing of large quantities of waste from domestic and industrial sources.
Figure 7.7 Mobius strip
The international symbol for recycle, reuse and reduce is a Mobius strip designed in the late 1960s. However, global recognition of this symbol ranks well below other symbols.
What factors influence the recognition of symbols?