writer：Ran Niu, Jiang Gong, Donghua Xu*, Tao Tang, Zhao-Yan Sun*
keywords：Percolation, Negative normal stress differences, Strain hardening, Network deformation
source：期刊
specific source：Colloids and Surfaces A: Physicochemical and Engineering Aspects 444 (2014) 120-128
Issue time：2014年
The rheological properties of amorphous carbon suspensions have attracted great attention, but they are still not fully understood due to the non-equilibrium nature of the structure. In this work, the linear and nonlinear rheological properties of ginger-like amorphous carbon (GC) filled silicon oil suspensions are investigated. The percolation threshold of GC/silicon oil suspensions is 1.2 wt.% based on linear viscoelasticity and percolation theory. Moreover, a viscosity plateau and apparent negative normal stress differences are observed during pseudo-steady shear experiments for samples with GC concentration above 6 wt.%. Furthermore, constant-rate shear flow confirms the evolution of structure as functions of shear rate and time. Additionally, strain softening of storage modulus and strain hardening of loss modulus are observed during strain sweep experiments for samples with GC concentration above the percolation threshold. Relating the rheological results with the structure observed by an in situ optical shearing cell, the change of viscosity and negative normal stress differences under pseudo-steady shear is supposed to result from the structure reorganization of GC networks.