  The micro/nano-structural evolution before and after tensile/compressive
loading, fatigue and ultimately, failure has been studied by Raman (and IR)
microspectroscopy for PBO, PET, PA66, PP, silk and hair using three probes: low
wavenumber collective modes at <150cm-1 as representative of the
crystalline/ordered and amorphous chains, stretching and bending modes, as
representative of the C-C/ C-N polymeric backbone, and localized vibrations
(OH, NH) to probe the inter-macromolecule segment distance. Wavenumber and
bandwidth distribution across fibre diameters reveal different types of
skin/core heterogeneity. The in situ analysis at different strain/pressure
levels shows that amorphous chains in the fibre accommodate the stress
differently. The post mortem analysis shows that amorphous domains can be higly
stressed during the failure and remnant stress can be measured.
