Specific surface area of poly-1,3,4-oxadiazole fibres of card structure

Poly-2,5-p,p′-diphenylenephthalide-1,3,4-oxadiazole fibres, in contrast to poly-p-phenylene-1,3,4-oxadiazole fibres, are porous and their specific surface area varies significantly as a function of the spinning method. Fibres spun from this polymer by the wet method have a more porous structure than those spun by the dry method. The chemical nature of the condensing agent (oleum or polyphosphoric acid) does not affect the chemical structure of the card polymer obtained.