The far-infrared spectroscopy of some synthetic organic polymers.

Studies have been made on the far-infrared spectra of poly(vinyl chloride), polyethylene, poly(4-methyl-1-pentene), poly(1-pentene) forms I and II, and poly(ethylene terephthalate), the spectra of poly(1-pentene) forms I and II being reported for the first time. The essential purpose of these studies was to establish 'assignments more firmly than hitherto, and thus to relate the spectral features to such properties as chain conformation, configuration and crystallinity. In the far-infrared spectrum of poly(vinyl chloride) the 185 cm-[1] band has been assigned to a vibration of an interchain hydrogen bond in the chain fold regions, and it appears that the 64 cm[-1] band is due to dipole-dipole interactions between adjacent chains. The frequency-temperature dependance of the 64 cm[-1] band was studied as it appeared to show an unusual variation, but results were not conclusive. However in the case of the 72 cm[-1] band in the spectrum of polyethylene two transitions were observed in the range 60 to 320 K which corresponded fairly well with previously reported transitions determined by other methods.Correlation of bands through the series of poly(?-olefins) has enabled assignments of bands in the far-infrared spectra of poly(1-pentene) forms I and II and poly(4-methyl-1-pentene) to be made for the first time. Some of the bands in the far-infrared spectrum of poly(4-methyl-1-pentene) are split into two components, and this has been attributed to non-uniformity of its helical structure. Additionally, the study has led to a re-assessment of the previous assignments given to bands in the far-infrared spectrum of poly(1-butene) form I, and certain re-assignments have been made.Finally, it has been possible to consolidate and extend assignments for the far-infrared spectrum of poly(ethylene terephthalate).