DYNAMIC INFRARED LINEAR DICHROIC SPECTRA OF PRESTRETCHED POLYPROPYLENE

DIRLD (dynamic infrared linear dichroic) spectra of prestretched isota ctic polypropylene have been recorded, The line shape features in the in-phase spectra are described on the basis of frequency shifts and ab sorption amplitude variations during the stretching cycle. Details suc h as the dichroism of the hands, direction of the shift, and changes i n the absorption intensities must be considered to explain signs and s hapes of the DIRLD hands, Evidence for chain reorientations under stre ss has not been found, The general principle of frequency shifts and c hanges in absorption intensities as the origin of DIRLD bands is demon strated by spectral simulations.