Probing The Difference Of Crystalline Modifications And Structural Disorder Of Isotactic Polypropylene Via High-Resolution Ftir Spectroscopy

Isotactic polypropylene (iPP) crystallized in different crystalline modifications has been investigated by highresolution FTIR spectroscopy. We focus on the spectral behavior of a band at -841 cm-1 that is generally employed as a probe to monitor the crystallization process of iPP. The peak position of the -841 cm-1 band (P841) in the IR spectrum of ?-form iPP is quite different from that of fl-form. However, the value of P841 for ?-form is roughly the same as that for ?-form. The above spectral behaviors are relevant to the packing modes of 31 helices in different crystalline modifications. Furthermore, P841 of the mesophase (842.05 cm-1) is evidently larger than that of the ?-crystal (840.84 cm-1), but is closer to that of the fl-crystal (841.55 cm-1). Additionally, the degree of structural disorder in the ?-crystal also exerts observable influence on P841, suggesting that the P841 is also suitable for detecting the change of structural disorder in ?-crystal. The results prove FTIR spectroscopy is still vitality nowadays for in-depth investigation of polymer crystallization.