Aspects of the Interaction of Native and Synthetic Polymers with Direct Dissolving Liquids

Because of the complex super molecular structure of cellulose the moulding into fibres, films and other shapes requires an antecedent chemical modification of the macromolecule or a direct dissolution step using solvents, which don't change it chemical nature. In the system NMMO/H 2 O/Cellulose the dissolution could be described on the basis of EDA interactions between cellulose and solvent. Based on the comparison of the different precipitation structures resulted from cellulose dopes in direct dissolving liquids or metal salts/NH 3 , cellulose xanthogenate in caustic soda and cellulose acetate in organic solvents different dissolution structures are assumed. Deduced from measurements of its manifest structural viscosity, the detected dissolving enthalpies of cellulose dopes in NMMO/H 2 O at different dissolution states and the high tenacity as well as high structural order (crystallinity) in Lyocell fibres and films an insertion of two NMMO monohydrate molecules into the H-bond bridges between OH group at the C6 of the one and at the C3 of the other polymer chain had been postulated leading to a more flexible structure while shaping into fibres. Because of the good drawability of dopes Lyocell fibres are characterised by outstanding textile mechanic properties but also by an extended fibrillation affinity. A simple transfer of these conclusions onto dissolution of polymers in ionic liquids (IL) seems not to be possible because of the fragmentary knowledge on IL. From the detected comparable dissolving viscosities and the known properties of cellulose fibres manufactured from solutions in ionic liquids ones had assumed a similar structure of cellulose IL complex as in the kind of the comparable direct dissolving agent (NMMO).