Paper Number
GG27 

Session
Arrested Systems: Gels and Glasses

Title
Accelerated yielding of binary colloidal gels

Presentation Date and Time
October 13, 2021 (Wednesday) 2:45

Track / Room
Track 6 / Ballroom 1

Authors (Click on name to view author profile)

1. Cho, Jae Hyung (Massachusetts Institute of Technology, Mechanical Engineering)
2. Bischofberger, Irmgard (Massachusetts Institute of Technology, Mechanical Engineering)

Author and Affiliation Lines (in printed abstract book)
Jae Hyung Cho and Irmgard Bischofberger
Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139

Speaker / Presenter 
Cho, Jae Hyung

Keywords
colloids; gels

Text of Abstract
When sheared at a stress that is large enough to induce plastic deformation yet small enough to prevent immediate fluidization, a colloidal gel creeps at gradually decreasing shear rates for a prolonged period of time, until it eventually yields and flows – a phenomenon known as delayed yielding. Using two types of polystyrene-poly(N-isopropylacrylamide) core-shell particles in water, we show that when the different types of particles are mixed, the resultant binary gel yields faster than the homogeneous gels composed of either type of particles. This accelerated yielding of the binary gel results from its lower critical strain at which the fluidization occurs. To investigate the mechanism for the distinct yielding timescales, we study the stress response of the gels in shear start-up and large amplitude oscillatory shear and find that the yielding of the binary gel is preceded by competing effects of strain-hardening and strain-softening, which lead to more brittle fracture.