Raman and IR micro-analysis of high performance polymer fibres tested in traction and compression

Understanding the nano- and macromechanical behaviour, the failure and fatigue mechanisms of advanced and natural polymer fibres by Raman/IR microspectrometry

“…When the H/D mole ratio is less than 10%, mechanical couplings are almost suppressed and the bandwidth of the X-H vibrator reflects the static and dynamic disorder [11]. In the case of PA66 fibre the N-H stretching mode appears made of two bands, a narrow one assigned to N-H vibrators in 'crystalline' environment and a broader one assigned to those in amorphous matrix [5]. Similar features are observed for Raman N-H fingerprint.…”

“…As an example, figure 6(a) compares the infrared signature of the PA66 fibre in its hydrogenated and deuterated forms: some modes shift according to the D/H mass effect [5] but the prominent change is the decrease of the bandwidth. When the H/D mole ratio is less than 10%, mechanical couplings are almost suppressed and the bandwidth of the X-H vibrator reflects the static and dynamic disorder [11].…”

“…Not only the position (wavenumber) but also the form (Lorentzian, Gaussian or more complex shape), the width and the polarization of the Raman and IR components gives valuable information on the composition (elongation modes are characteristic of the chemical bonds or molecular functions), the short-range to long-range structure (polarizations and collective low energy modes) and the texture (polarization and wavenumber mappings) of the fibres. The comparisons of polarized signatures for horizontal (H) and vertical (V) configurations obtained by changing the orientation of the fibre with respect to the laser and spectrometer slit entrance, is a good means for measuring the axial and/or crystalline character of the fibre [3][4][5].…”

Nanomechanics of single silkworm and spider fibres: a Raman and micro‐mechanical in situ study of the conformation change with stress

“…Comparison is made with keratin 7 and isotopic diluted and hydrogenated polyamide (PA 66) spectra. 1,2,19 This figure is available in colour online at www.interscience.wiley.com/journal/jrs.…”

“…Note that our description with a Lorentzian line, as expected from Raman theory for ordered vibrational units, and a Gaussian one for disordereď -conformation allows a fit with fewer number of bands than used by others groups. 19,20,59 According to this model, the bandwidth of Lorentzian˛0 component is lower than those of the Gaussian ones (Tables S1-S3, Supplementary Materials) and must be assigned to a structure intermediate between regular˛-helix and disorderedˇ-ribbons: the random coil. According to the above assignments, the˛-helix signature disappears in the film spectra (Table S2, Supplementary Materials , Figs 7 and 9).…”