Measurement of the variation of crystal lattice structures of ethylene copolymers with high‐resolution cryogenic FTIR spectroscopy

Abstract

High-resolution cryogenic Fourier transform infrared spectroscopy (FTIR) was used to measure the variation of the unit cell volume of ethylene-octene copolymers (EG) in this study. It was found that both the comonomer content and thermal history have great influence on the crystal lattice structure of ethylene polymers. With the increase of the octene content, the unit cell volume of EG copolymers expand, and quenching treatment favors the increase of distance between two molecular chains in orthorhombic crystals and causes more crystal lattice deformation. Compared with traditional wide-angle X-ray diffraction method, high-resolution cryogenic FTIR spectroscopy, as a powerful technique for measuring the changes of crystal lattice structures of polyethylene and ethylene copolymers, can provide more accurate information on the characterization of the changes of crystal lattice structures of semicrystalline polymers.