Influence of Methocel cellulose ether additive on micro-scale friction, abrasion and energy dissipation of rough-heterogeneous particles

Abstract

Understanding and modeling the contact behavior of particles provides enhanced constitutive laws in discrete-based simulations as well as a strong linkage between micro- and macroscopic behavior of granular materials. In the present study, we studied the influence of a polymer-based additive composed of Methocel cellulose ether on the tribological response of rough particles with grain-scale experiments. We performed both monotonic and cyclic tests on pairs of particles subjected to repeated shearing so that to explore the additional influence of abrasion in relation to previous loading history. Each sample was tested at first in a dry state and consecutively was immersed into the polymer-based fluid. The test results indicated increased friction at the contacts of the particles when immersed in the polymer-based additive, suggesting promising applications of the Methocel cellulose ether in improving the stability of geo-systems. For the shearing tests in a dry state, abrasion influences were amplified at higher magnitudes of normal load, whereas the polymer additive acted as a fluid film (or thin coating) mitigating in this way the continuous abrasion due to repeated shearing. We incorporated the Mindlin and Deresiewicz (M–D) contact model in a modified form to analyze the tangential response of the particles. It was found that the power of the modified M–D model was directly correlated with the natural logarithm of the microslip displacement threshold, when this threshold was normalized with respect to the normal load. Based on the analysis of the closed loops from the cyclic tests, the energy dissipation was found to be reduced when the samples were immersed in the polymer fluid compared with the tests in a dry state. The test results from the present work offer some insights into the micromechanical-based analysis of particulate materials and the interactions of rough particles in the presence of polymeric fluids with potential applications in contact mechanics modeling using discrete-based tools. These results also contribute to unveiling the prevailing micromechanisms in order to understand (or interpret) bulk behavior, thus the database from the present work may provide helpful guidance in understanding granular material behavior and the interactions between particles with polymer-based additives.