用红外光谱法研究聚氯乙烯的增塑机理

傅立叶变换红外光谱法用于探测增塑聚氯乙烯 (PVC)的构象和结晶的变化。研究中采用的增塑剂为邻苯二甲酸二辛酯 (DOP)、邻苯二甲酸二正丁酯 (DBP)和癸二酸二辛酯 (DOS)。用差谱技术在除去增塑剂对总的红外光谱的贡献后,研究在600～700cm^-1范围内由PVC增塑作用引起的构象变化。将增塑的PVC与未增塑的PVC光谱进行比较,结果发现增塑PVC的光谱中某些C—Cl伸缩振动光谱带有明显的位移,这个结论突出了增塑PVC的构象变化,这种变化取决于增塑剂的用量和种类。通过1426cm^-1 (TTTT构象、结晶 )和1434cm^-1 (无定形)吸收带的吸收度比值 ,研究了由PVC增塑作用引起的结晶变化,比值的大小与增塑剂的用量和增塑PVC的存放时间有关。根据构象和结晶度的变化可以确定增塑剂的增塑效果,为选择增塑剂提供了理论依据。

Study of the mechanism in plasitized PVC with infrared spectrography

Fourier-transform infrared spectroscopy(FT-IR) was used for studying conformational and crystal change in plasticized poly(vinyl chloride)(PVC). Three plasticizers were used: namely dioctyl phthalate (DOP), di n butyl phthalate (DBP) and di(-2-ethyl-hexyl)sebacate(DOS). The conforma tional change induced by plasticization of PVC was studied in the 600～700cm^-1 range after eliminating the plasticizer contribution to the total spectrum with subtraction technique. It is found that the wave number shifts of some ν(_C—Cl)stretching vibration are evident in plasticized PVC in comparison with unplasticized sample. The result emphasizes conformational change in plasticized PVC. This change depends on the amount and kinds of plasticizers used. The crystal change induced by plasticization of PVC was investigated by the ratio change of the absorptionat the 1426 cm^-1 ( TTTT , crystal) and 1434 cm^-1 (amorphous) bands. This change depends upon the amount of plasticizer used and also storage time of plasticized PVC. The plasticizing effect of plasticizers may be specified according to the conformational st ructure and the crystal change. Thus , they provide a FT-IR、TTTT theoretical basis for selecting plasticizers.