Infra-Red Absorption Spectra of Some Polymers at Liquid-Helium Temperatures

Abstract

Infra-red absorption spectra of polythene, rubber, polystyrene and polyvinyl chloride have been obtained at 4° absolute, in the rocksalt region, in a specially designed transmission cell containing liquid helium. No unusual changes occur on cooling which considerably alter the absorption. Some sharpening and improvement in resolution occurs, but the widths of most bands in polymers remain wide. In polythene one component of the doublet at 720 cm−1 becomes very sharp (possibly even less than the experimental value of the slit width, 1 cm−1). Its companion remains broad, about 4 cm−1. The two components are interpreted as CH2 wagging in trans- and cis-configurations of the hydro-carbon chain.

Analyzing the network formation and curing kinetics of epoxy resins by in situ near-infrared measurements with variable heating rates

“…It is known that the signals of vibrational spectroscopic measurements are influenced by temperature [50,51]. In order to investigate the dependence of temperature on the absorption bands, pure DGEBA was heated from 30 °C up to 90 °C at 10 K min -1 and cooled down to 30 °C.…”

Polyethylene: Preparation, Structure, And Properties

“…This conclusion is supported by the studies of C36 hydrocarbon crystals with polarized infrared radiation (274). The earlier interpretation (249) of this doublet was in error.…”

“…"1 region and the doublet at 721-730 cm.-1 The doublet at 721-730 cm.-1 is characteristic of solid polyethylene and crystalline paraffin hydrocarbons. When the sample has been cooled to 4°K., the band at 730 cm.-1 becomes very sharp, while its companion at 720(721) cm.-1 remains unchanged (249). When polyethylene melts, the doublet with maxima at 721 cm.-1 and 730 cm.-1 is replaced by a broad band centered at 721 cm.-1 (441,482,501).…”

“…Infrared absorption has been found to be a valuable tool in the study of the fine structure of polyethylene. In table 1 are listed the absorption bands in the 2 to 15 µ region that have been observed in polyethylene (1,39,56,100,158,248,249,274,436,439,440,441,467,482,501,502) and their assignment to the various molecular xdbrations. Infrared study has recently been supplemented by Raman spectra of crystalline polyethylene and long-chain hydrocarbons (357,534).…”

Low-temperature absorption spectroscopy (cryoabsorption spectroscopy)

“…The spectra of proteins at low temperatures show changes due to their aromatic amino acid components (29,30) or to prosthetic groups such as hemes (31) or carotenes (10). Amorphous polymeric molecules at 4°K, show very small spectral changes, although one band of a crystalline polymer polythene was sharply narrowed (32).…”