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Fourier transform infrared temperature studies of an amorphous polyamide are presented. The results strongly suggest that prior interpretations of the changes occurring in the N-H stretching region of the spectra of polyamides and polyurethanes with temperature were greatly oversimplified. In essence, these spectral changes were interpreted to be solely due to hydrogen-bonded N-H groups transforming to "free" N-H groups. Subsequent use of these data to obtain thermodynamic parameters associated with hydrogen bond dissociation must now be considered erroneous.The primary factor not taken into account concerns the very strong dependence of the absorption coefficient with hydrogen bond strength. With increasing temperature, the average strength of the hydrogen bonds decreases, which is observed in the infrared spectrum by a shift to higher frequency. Concurrently, the absorption coefficient decreases, leading to a reduction in the absolute intensity of the hydrogen-bonded N-H band. In this study we present experimental results in the N-H stretching and amide I, II, and V regions of the infrared spectrum of an amorphous polyamide. In addition, we present a model, justified by theoretical considerations, which we believe advances our understanding of the strong dependence of absorption coefficient with the strength of the hydrogen bonds. The ramifications of this work to hydrogen-bonded polymers are discussed.

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The results of a Fourier transform infrared study of poly(ethylene-co-methacrylic acid) (EMAA) copolymer blends with poly(2-vinylpyridine) (P2VP) and a copolymer of styrene and 2-vinylpyridine are presented. EMAA copolymers are strongly self-associated at ambient temperatures through the formation of intermolecular carboxylic acid dimers. P2VP, a polymer that is inherently weakly self-associated, forms a strong association with EMAA by forming intermolecular hydrogen bonds between the carboxylic acid and pyridine groups. The fraction of interacting sites in these blends plays a major role in determining the solution and film forming properties of the mixtures and ultimately the degree of molecular mixing of the two polymers. Quantitative measurements of the fraction of pyridine groups that are hydrogen bonded to carboxylic acid groups have been obtained, and the results are discussed in terms of competing equilibria.

The problems associated with the application of FT-IR to the characterization of coal structure are critically discussed. The controversies concerning band assignments are considered and it is concluded that the strong 1600 cm−1 band can be assigned to an aromatic ring stretching mode that in most coals is intensity enhanced by the presence of phenolic groups. The application of computer routines to the determination of OH and CH groups is considered. Established criteria for curve fitting are applied to the problem. Qualitative identification of functional groups is achieved, but consistent quantitative measurements will require a determination of the relationship between the extinction coefficients of resolved bands.

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