Analysis of C-H Stretching Vibration of Polypropylene by Two-Dimensional Infrared Spectroscopy

Polypropylene molecular structure was determined through analysis of C-H Stretching Vibration (νC-H) by one-dimensional infrared spectroscopy, second derivative infrared spectroscopy and fourth derivative infrared spectroscopy in the range of 3 000-2 800 cm-1. There were methyl asymmetrical stretching vibration mode (νasCH3)、 methyl symmetrical stretching vibration mode (νsCH3)、 methylene asymmetrical stretching vibration mode (νasCH2)、 methylene symmetrical stretching vibration mode (νsCH2) and methyne stretching vibration mode (νCH). The effect of temperature on C-H scissoring bond vibration (νC-H) of polypropylene was further studied by two-dimensional infrared spectroscopy. It was found that, as the temperature increased, the sequence of intensity change speed was 2 875 cm-1(νsCH3), 2 890 cm-1(νCH), 2 932 cm-1(νasCH2), 2 975 cm-1(νasCH3), 2 855 cm-1(νsCH2).