Viscous and elastic properties of water-soluble cellulosic derivatives regarding to application

Cellulose derivatives as an example for water soluble polymers from renewable resources have gained great importance for the industrial application over the last years. However, the flow property profile of aqueous solutions of cellulose derivatives is not only depending on the chemical composition and substitution pattern, solvent, temperature and concentration but also on the molar mass and the particle size in solution. A correlation of these structure properties with the shear flow properties like the viscosity yield of a cellulose derivative can be obtained for each homologous derivative series of a specific degree of substitution via empirical relationships as the Mark-Houwink-Sakurada-relationship ([]-M- relationship), the 0-[]-c relationship or the -[]-c and the N1-[]-c relationship for the elastic properties of a solution. The elastic response can also be captured via oscillatory agitation of a sample that yields the moduli and hence the network parameters of the cellulose derivative in solution. However, to fully characterize the flow properties in technically relevant problems, also the elongational properties of a solution need to be determined. Lately it could be shown that this is now possible for aqueous solutions of cellulose derivatives with capillary break-up extensional rheometry (CaBER) experiments [1], which probe the transient behaviour of fluid threads of polymer solutions to extract the transient extensional viscosity and relaxation times to correlate these material functions with others of the rheological cycle and the molar mass and the molar mass distribution (MWD).status: publishe