A rheo-optical FTIR spectrometer for investigating molecular orientation and viscoelastic behavior in polymers

A rheo-optical Fourier transform infrared (FTIR) spectrrometer has been developed by combining step-scan FTIR spectroscopy with elements of polarimetry and rheometry in order to investigate both deformation-induced morphology changesand orientation/relaxation dynamics of components within complex polymers. This versatile instrument instrument can directly and sensitively measure quantitative infrared spectra at different temperatures and for different deformation processing modes. A complex multiple-modulation/demodulation processing scheme is used to extract both absorbance and dichroism information from a single detector signal. Experimental results from a semicrystalline isotactic polypropylene and a thermoplastic polyurethane are reported in order to illustrate instrument capabilities.