Most packaging technologies operate with secondary recycling, i.e. a
physical reprocessing involving grinding, melting, and reforming plastic
packaging material, that may also undergo different reforming
conditions, such as different processing temperatures, the use of
vacuum stripping, or other procedures, that could influence
contaminant levels. Use in the recycled polymer of a new additive or an
amount of an approved additive in excess would require a special
analysis. Time-domain terahertz transmission spectroscopy (TDTTS)
has become a powerful method for studying properties of various
materials, due to its advantages as: penetration of a wide variety of
non-conducting materials; sensitive to charge carriers; selective to
numerous organic molecules through particular absorption and
dispersion; no need for a coupling medium and low photon energies.
TDTTS operates with sub-picosecond pulses of electromagnetic
radiation, bridging a large frequency gap between microwave and
conventional infrared spectroscopy. Materials or biological structures
have their intrinsic THz spectra in the absorption and the refractive
index, called as “fingerprint” THz spectra, bands of which originate in
intermolecular and intramolecular vibrations. The main objective of the
project is to adapt THz time-domain spectroscopy for the development
of an innovative method for selective and sensitive early identification
and quantification of biological and/or chemical contaminants remnant
in recycled PET packaging. The proposed THz test technology for food
packaging application, as described in the project, was never and
nowhere developed in this way, but will be based on scientific
approaches described in the last 5 years, relate.d to its 2 components:
a) TDTTS method and equipment, eventually with analytical modeling
and test characteristics analysis and b) molecular dynamics simulation
of molecules, analytical modeling and formulation in THz domain