Spectroscopic analysis and kinetics of intermolecular hydrogen bond formation in poly-pyridobisimidazole (M5) fiber

• Published in: Journal of polymer science. Part B, Polymer physics Polymer physics, 2009-09, Vol.47 (18), p.1809-1824
• Main Authors: Leal, A. Andres, Deitzel, Joseph M., McKnight, Steven H., Gillespie Jr, John W.
• Format: Article
• Language: English
• Subjects: Annealing; Applied sciences; Bands; Bonding; Exact sciences and technology; Fibers; Fibers and threads; Forms of application and semi-finished materials; Fourier transforms; Hydrogen bonding; Infrared; infrared spectroscopy; poly-pyridobisimidazole; Polymer industry, paints, wood; Reproduction; Technology of polymers; Vibration
• ISSN: 0887-6266; 1099-0488; 1099-0488
• DOI: 10.1002/polb.21767

Poly‐pyridobisimiazole (M5) single filaments subjected to varying degrees of heat treatment have been analyzed using Fourier Transform Infrared (FTIR) microspectroscopy in transmission mode to detect changes in the state of intermolecular hydrogen bonding as a function of fiber annealing conditions. The FTIR absorbance bands associated with hydrogen bonding in M5 fiber have been identified, and the integrated molar absorption coefficients for the bands of interest have been determined experimentally, which allows to quantify the concentration of NH vibration groups hydrogen‐bonded (H‐bonded) to water molecules, and the concentration of NH vibration groups H‐bonded to adjacent polymer chains in the fiber. A dual mechanism kinetic rate expression is used to describe intermolecular H‐bond formation in M5 fiber as a function of annealing conditions, from which an activation energy for H‐bond formation of 14.8 kJ/mol is obtained. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1809–1824, 2009