Influence of structure on mechanical properties of regenerated cellulose fibres

Comparative structure analyses of the new lyocell fibres and regular viscose and modal type were made in order to explain the reasons for differences in mechanical properties of fibres. The mechanical properties which where determined in conditioned state reflect the effect of the structure. in wet State they reflect the effect of the aqueous medium on the chanties: in supermolecular structure in wet treatments. The structure analysis shows that the new lyocell fibres consist of longer molecules, they have a greater degree of molecular orientation and degree of crystallinity, and the voids structure (diameter, volume, inner surface) is similar To that of viscose fibres. The structural characteristic of the lyocell fibres (highest orientation factor and crystallinity index) assure better mechanical properties, particularly in wet state. The mechanical properties of the modal fibres in conditioned state are similar to those of lyocell fibres. Greater differences between both types of fibres were found in the wet state (lyocell fibres keep in wet 91% of breaking strength in dry, viscose and modal fibres just around 50%).