Viscoelastic properties of tightly entangled polymeric systems

The rheology of semiflexible polymer solutions has attracted much attention now because it provides a basis for fundamental understanding the physical properties of cellulose nanofibers, which have been considered to be a new material for sustainalbe society. This talk describes recent experimental findings on the rheology of semiflexible polymers including cellulose derivatives and DNA. In addition to the orientational stress of the viscoelastic segment, the bending and tension modes of the segment contribute to the viscoelasticity of the semiflexible polymer solution. In particular, in tightly entangled systems, where the entanglement length is shorter than the persistent length, the bending mode significunlty contributes to the viscoelasticity of the rubbery plateau region. In this talk, by combining simultenous mesurement of strain-induced birefringence, the mode separation of orientation, bending, and tension is carried out on on the linear viscoelasticity of the model materials, and the contribution of each mode is quantitatively discussed.