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Investigation of aged polymers and adhesives by THz and FTIR spectroscopy

Plastic and adhesive compounds of plastic are in common everyday use and are increasingly used as construction materials, also in safety-critical areas. Especially strain, stimulated by high temperature, leads under the influence of atmospheric oxygen to a degradation of the polymer. This results in the loss of stability and of mechanical capacity to withstand stresses. Early perception of changes in the morphology of polymers caused by thermo-oxidative aging is therefore of great importance.

Electromagnetic radiation within the THz frequency area (100GHz to 4 THz) is suitable for fluoroscopy of plastic in order to find imperfections and inclusion. In recent works, we could connect morphological aspects like glass-transition-temperature or crystallization level with signal changes within the THz frequency area.

In comparison to common IR-spectroscopy, the THz time-domain spectroscopy (THz-TDS) offers the possibility to measure the index of refraction beside the absorption values, which is often related to a macroscopic property.

The objective of this thesis is to age common polymers thermo-oxidatively and to characterize their signature through THz-TDS and FTIR technology in the IR area in order to elaborate the advantages and disadvantages of the technologies with regard to the measurement of degradation.

Contact: Prof. Dr. Martin Koch