The orientation behaviour of molecular chains of hard elastic polypropylene(HEPP) film was investigated on the uniaxial stretching by polarized IR Vibration-Mechanical Spectrosco-py. It was found that there are three components in the IR spectrum between 1130 cm-1 and 1190 cm-1. The orientation behaviour was measured using second derivative

deconvolution

curve-fitting programs and IR differencial spectra technology by computer. The bands at 1167 cm-1 and 1152 cm-1 may be related to the crytal conformation of HEPP long and short spi-ral chains respectively. The dichroism change of 1167 cm-1 band to different draw ratio is in agreement with 998 cm-1 crystal band on polarized IR spectra. A new band at 1159 cm-1 can be assigned to the amorphous hand.