Detailed examination of nitrile stretching vibrations relevant for understanding the behavior of thermally treated polyacrylonitrile

The influence of electronic and environmental effects on the wave number of nitrile stretching vibrations was examined with respect to moieties relevant for the polyacrylonitrile homopolymer and its assumed transformation products on thermal treatment in the course of carbon fiber production on the basis of four sources of information. Literature values were collected. Fourier transform infrared (FTIR) measurements on relevant commercially available compounds were performed. For the first time, model compounds were synthesized and examined, and for the first time, density functional theory calculations for unavailable important compounds were performed. The results place the interpretation of the FTIR data on much safer scientific ground than any other study before; in particular, they unequivocally disprove suggestions given in the previous literature and provide quantitative relative oscillation strengths for important peaks necessary for the quantitative kinetic evaluation of the changes, which will enable the systematic fine-tuning of new proposals. (c) 2017 Wiley Periodicals, Inc.