Hydrogen bonding in polymers. 2. Infrared temperature studies of nylon 11

Hydrogen bonding, mobility, and structural transitions in aliphatic polyamides

“…132,133 Moisture downshifts the temperature of onset of this increase in the population of free NÀ ÀH groups and, as a result, the longitudinal mobility of the chains in the amorphous regions. Mechanical relaxation data show that there is a critical value of the number of water molecules per amide group for the onset of a relaxations in wet nylons, and this changes with the type of nylon: 0.2 for PA-4 and 0.4 for PA-6.…”

Variable‐temperature FTIR studies on thermal stability of hydrogen bonding in nylon 6/mesoporous silica nanocomposite

“…Because the hydrogen bonded N-H stretching band is not a conformationally sensitive mode, its wavenumber does not exhibit separable features attributable to ordered and disordered hydrogen bonded conformations. 19 Therefore, this band reflects, on the whole, the hydrogen bonded N-H stretching of both crystalline phase and amorphous phase.…”

“…The presupposition was that the absorption coefficient did not vary significantly with www.interscience.wiley.com/journal/pi 30 3300 3301 40 42 80 3306 3303 48 43 120 3309 3307 50 44 160 3313 3310 54 46 180 3314 3312 60 47 200 3331 3313 64 48 220 3335 3315 78 62 240 3341 3328 80 70 temperature. However, Skrovanek et al 18,19 discovered that the absorption coefficient of N-H stretching depends strongly on the temperature and the strength of hydrogen bonding; therefore, the procedure of Schroeder and Cooper and their results should be questionable. Skrovanek et al 19 also pointed out that the broadness of this band reflects, in large part, a distribution of hydrogen bonded N-H groups of varying strengths dictated by distance and geometry.…”

“…However, Skrovanek et al 18,19 discovered that the absorption coefficient of N-H stretching depends strongly on the temperature and the strength of hydrogen bonding; therefore, the procedure of Schroeder and Cooper and their results should be questionable. Skrovanek et al 19 also pointed out that the broadness of this band reflects, in large part, a distribution of hydrogen bonded N-H groups of varying strengths dictated by distance and geometry. We believe that the views expounded by Skrovanek et al are more reasonable, and therefore we chose the method of Skrovanek et al to analyze the hydrogen bonded N-H stretching band.…”

“…However, W 1/2 is mainly a reflection of the distribution of hydrogen bonded groups at different distances and geometries: the broader the band is, the more disordered the hydrogen bonds are in the sample. 2,19 Therefore, we use W 1/2 and the rate of change of W 1/2 as measures to compare the strength distribution and thermal stability of hydrogen bonding between N6 and NMSN.…”