(Nano)structure, skin/core and tension behaviour of polyamide fibres
Résumé
The micro/nanostructural evolution of ultrahigh-performance and textile (containing a dispersion of TiO2 powder) polyamide 66 fibres during tensile loading and failure initiation was studied using Raman spectroscopy low-wavenumber collective modes (100 cm-1) as a mechanical probe representative of the crystalline domains. The analysis of the wavenumber distribution revealed the skin/core heterogeneity. A compressive residual stress in the skin was evaluated at about 200 MPa from calibration plots. The homogeneity of the TiO2 grain dispersion was mapped on fibre sections and scanned along their lengths. In situ analysis at different strain levels shows that the amorphous region accommodates the stress up to ca 350 MPa, from which point elastic behaviour is observed. Particular attention was devoted to analysing crack formation