Dye aggregations or crystals within the void places of polyvinyl alcohol fibre

The visible absorption spectra of the cross-section of dyed PVA fibre with AO were measured by means of a microspectrophotometer. The spectra showed a high maximum at 475 nm, which would be referred to as β-band (a monomer peak at 498 nm). Many void places were recognized in core layer by electron or scanning electron microscopy. It was explained that the dimer band mainly arose from dye aggregates or crystals at the void places of fibre.