Dynamic infrared spectroscopy with a step-scan FT-IR for the characterization of polymers

Step Scan creates an identical IR modulation frequency over the entire IR spectrum. This is a prerequisite for quantitative photoacoustic spectroscopy and depth profiling. 2D correlation maps have been created for photoacoustic spectra as well as for dynamic difference spectra of polymers under periodic external mechanical perturbation. From the positions and signs of cross peaks in the 2D-maps the relative direction and timing of reorientational motions can be determined Depth profiling has been demonstrated on ethylene-vinyl acetate copolymer on polypropylene. The effects of mechanical stress on polymers using 2D-FT-IR of have been shown for isotactic polypropylene and a polyesther/polyurethane block copolymer.