Rheology Of The Colloidal Glass Transition As Compared To The Molecular Glass Transition And Gelation
July 21-24, 2019
Is there a difference between a gel and a soft glass? Rheology can tell. This will be explored within the general framework of “soft matter” (SM), which is a common term for many viscoelastic liquids and solids such as polymers, emulsions, paints, food materials, and biological tissue. SM combines viscous and elastic properties in intriguing ways. Common features are a low modulus (low complex modulus for liquid SM) and slow relaxation of stress. The internal structure typically is out of equilibrium. Most SM is very fragile due to SM’s low modulus, where a low stress already causes large strain and internal rupturing (yielding). Quite often, it is hard to decide whether a specific SM is a liquid or solid. This shared rheological behavior makes all kinds of SM similar in appearance, however, individual relaxation patterns and viscoelasticity in general can be vastly different between one SM and another. This is where rheology becomes interesting. Time-resolved rheological methods for SM will be introduced and an attempt will be made to classify SM in terms of their characteristic relaxation patterns. This will be shown with rheological experiments on colloidal glasses and molecular glass formers, and on chemical gels and physical gels for comparison.
H. Henning Winter, "Rheology Of The Colloidal Glass Transition As Compared To The Molecular Glass Transition And Gelation" in "Colloidal, Macromolecular and Biological Gels II", Samiul Amin, Manhattan College, USA Saad Khan, North Carolina State University, USA Srini Raghavan, University of Maryland College Park, USA Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/cmb_gels_ii/13