Citation

Peiyi Wu*, Yuliang Yang, and H. W. Siesler. Two-Dimensional near-Infrared Correlation Temperature Studies of an Amorphous Polyamide. Polymer 2001, 42, 10181-10186.

Abstract

Near-infrared spectra of a totally amorphous polyamide measured over the temperature range 25–200°C was analyzed using generalized two-dimensional (2D) correlation spectroscopy. At least, five distinct bands at 5690, 5810, 5900, 5980 and 6010 cm−1 were identified in the region of the CH overtones (5200–6200 cm−1). Among them, two bands at 5810 (aliphatic) and 6010 cm−1 (aromatic) are found to be very sensitive to the temperature-induced structural changes of the polyamide under examination. In the ν(NH) overtone region (6300–6800 cm−1), the asynchronicity of the bands assigned to the vibrations of the free and hydrogen-bonded NH groups indicate a complicated dissociation mechanism and the existence of different hydrogen-bonded species in the investigated totally amorphous polyamide sample. Owing to the spectral resolution enhancement in 2D correlation spectra, a splitting of the first overtone of the free NH stretching vibration into two components at 6780 (totally free) and 6740 cm−1 (free-end) can be observed.