Hydrogen bonding in nylon

The predominant intermolecular bonds in nylon 6 are hydrogen bonds resulting from the highly polar -NHCO- amide linkages. On the other hand, polyethylene is held together by van der Waals forces, which are much weaker than the polar hydrogen bonds in nylon 6. 

FIGURE 14.11 Hydrogen bonding in nylon-6.6. Hydrogen bonds are highlighted in blue shading. 

Our model repre.sentation of the oriented fiber is given in Fig. 3. The nodes in the figure represent the elementary repetition units of the polymer chains, i.e. methyl units for polyethylene. For very long chains, each node is made to correspond to more than one repetition unit (Termonia et al., 1985). The nodes are joined in the x- and z-directions by secondary bonds having an elastic constant Ki. These bonds account for the intermolecular vdW forces in polyethylene or hydrogen bonds in nylon. Only nearest-neighbor interactions are considered. In the y-direction, stronger forces with elastic constant K account for the primary bonds, i.e. C-C bonds in polyethylene. 

Figure 21.37 Hydrogen bonding in nylon 66. This property is responsible for the ability of nylon fibers to stretch. 

Figure 18.2. Ionization of hydrogen bond in nylon fibers.

FTIR spectroscopy has been used to study hydrogen bonding in nylon as suggested in the literature (3). In each of our experiments 200-400 scans were averaged, processed, and compared against a previously ran background spectrum of the empty cell at the same temperature. The spectral resolution was set at 1.0 cm". Spectra were recorded at a number of temperatures between 23 and 280 °C. Prior to data collection, the cell was equilibrated for at least 5 minutes at each temperature. CO2 saturation time in the first measurement was 60 minutes to reach sorption equilibrium. Subsequently, once the test temperature was reached, an equilibration time of... 

Nylon-6,6, 2, 136, 530. See also PA-6,6 acid-catalyzed hydrolysis of, 568 acidolysis of, 568 alkaline hydrolysis of, 568-569 ammonolysis of, 555, 570 chemistry and catalysis of, 546 creation of, 1 hydrogen bonding in, 539 hydrolysis of, 531, 544, 552-555 phase-transfer-catalyzed alkaline hydrolysis of, 569-570... 

Koberstein J.T., Gancarz I., and Clarke T.C., The effect of morphological transition on hydrogen bonding in PU Preliminary results of simultaneous DSC-FTIR experiments, J. Polym. Sci. B, 24, 2487, 1986. Skrovanek D.J., Painter P.C., and Coleman M.M., Hydrogen bonding in polymers 2. Infra red temperature studies on nylon 11, Macromolecules, 19, 699, 1986. 

Nylon 4,6 PoIy(ethylene-vinyIaIcohoI) copolymer, 27 moI% elhylene, 13 moI% vinyl acetate nylon 4/nylan 6 69/ 31 mol% films cast from formic acid FT-IR, X-ray, DSC, tensile tests Miscible when nylon 4>6 <35 wi%.C-0-N-H hydrogen bond between nylon and EVOH. Increase in tensile strength from 4 for 15/85 wt% nylon/EVOH to 331kgcm for 100/0 blend (82)... 

The crystallisation from melt in a temperature gradient or in contact with a surface acting as a nucleating substrate may result in a transcrystalline structure with the growth a.xis of the crystals, the h-axis in the case of polyethylene, the hydrogen bonds in the case of nylon parallel to the gradient or perpendicular to the substrate. 

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