pps proceeding - Abstract Preview
pps proceeding
Symposium: S01 - (General Session 1) Rheology and Rheometry
Keynote Presentation
 
 

Soft Solid Rheology

Winter H. Henning (1)*

(1) University of Massachusetts Amherst - Amherst - USA

Distinct viscoelastic patterns govern the rheology of amorphous materials in the soft solid state beyond their gel point. The properties of the evolving material states are governed by increasing connectivity. Typical rheological features are a growing relaxation modulus and accelerated relaxation processes for the structural components that can still relax. Time-resolved rheology measurements, in combination with time-cure superposition, on two model materials show this soft solid behavior. One model material (self-exfoliating clay-polymer composite) is chosen to represent soft physical gels and the other one (crosslinking polyurethane) to represent soft chemical gels. The relaxation characteristics near the gel point are different for the two materials. For the physically gelled material, the modulus growth was found to be inversely proportional to the relaxation time decay. For the chemically gelled material, the modulus grows only with a factor of about 0.7. More gelling materials are going to be included in the study since it is unclear how widespread the observed viscoelastic patterns occur. Keywords: Gelation, Time-Cure Superposition, Time-Resolved Rheometry, Linear Viscoelasticity