  Flax fibres are valuable reinforcements for tomorrow's composites. However,
defects called kink-bands, which mainly appear on fibres during the extraction
and transformation phases, might affect their mechanical properties. Defects
induced pores, within the kink-band are investigated in this work. They were
morphologically explored using synchrotron phase-contrast X-ray
microtomography, a technique that displays a sharp 3D representation of the
pores. The study highlights the link between kink-bands and secondary cell wall
ultrastructure. Pores are organised concentrically around the lumen, and their
low thickness suggest that they are located at the interface between cellulose
layers within S2 (G) layer. Moreover, the pores inclination with reference to
the lumen axis follows the typical microfibrillar angle changes observed in the
literature in the kink-band region. The volumes of the pores were measured, and
a local increase in porosity was revealed in zones where defects are most
severe along the fibre.
