Abstract
The dynamics of entangled polymeric solutions were studied using drag of borosilicate discs and conventional shear rheometry devices in order to understand the effect of deformation on the relaxation process and the possible influence of slower processes such as tube reorganization. In order to compare the results obtained from both types of deformations, the drag force was normalized with the expected Newtonian behavior and a normalized viscosity was obtained. In both geometries, the presence of different and well defined power law regimes was found. The slower rate regime is characterized with an exponent close to -0.5, which can be related to the influence of constraint release in the dynamics of highly entangled polymer systems. The influence of non-bulk effects, such as slip, was resolved by the surface modification of the dragged discs and aluminum cone and plate fixtures, which was obtained through the grafting of different molecular weight polymer chains. A change in the force magnitude was observed principally at high entanglement density systems, however, the viscosity power law response was not critically modified.
Sanchez Reyes, Javier (2000). Non-linear viscoelastic deformation of polymeric solutions. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2000 -THESIS -S258.