二维红外光谱法分析聚丙烯C-H伸缩振动
Analysis of C-H Stretching Vibration of Polypropylene by Two-Dimensional Infrared Spectroscopy
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摘要: 在3 000~2 800 cm-1范围内,分别测定聚丙烯C-H伸缩振动(νC-H)的一维红外光谱、二阶导数红外光谱和四阶导数红外光谱来确定聚丙烯的分子结构。试验发现聚丙烯νC-H主要包括甲基碳氢不对称伸缩振动模式(νasCH3)、甲基碳氢对称伸缩振动模式(νsCH3)、亚甲基碳氢不对称伸缩振动模式(νasCH2)、亚甲基碳氢对称伸缩振动模式(νsCH2)和次甲基碳氢伸缩振动模式(νCH)。进一步采用二维红外光谱研究了温度对聚丙烯νC-H的影响。研究发现,随着温度的升高,聚丙烯分子中νC-H红外吸收强度变化快慢顺序为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)。Abstract: 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).
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