Critical Shear Rate of Polymer-Enhanced Hydraulic Fluids
Many application-relevant fluids exhibit shear thinning, where viscosity decreases with shear rate above some critical shear rate. For hydraulic fluids formulated with polymeric additives, the critical shear rate is a function of the molecular weight and concentration of the polymers. Here we presen...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-11-01
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| Series: | Lubricants |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2075-4442/8/12/102 |
| _version_ | 1797546872177426432 |
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| author | Pawan Panwar Paul Michael Mark Devlin Ashlie Martini |
| author_facet | Pawan Panwar Paul Michael Mark Devlin Ashlie Martini |
| author_sort | Pawan Panwar |
| collection | DOAJ |
| description | Many application-relevant fluids exhibit shear thinning, where viscosity decreases with shear rate above some critical shear rate. For hydraulic fluids formulated with polymeric additives, the critical shear rate is a function of the molecular weight and concentration of the polymers. Here we present a model for predicting the critical shear rate and Newtonian viscosity of fluids, with the goal of identifying a fluid that shear thins in a specific range relevant to hydraulic pumps. The model is applied to predict the properties of fluids comprising polyisobutene polymer and polyalphaolefin base oil. The theoretical predictions are validated by comparison to viscosities obtained from experimental measurements and molecular dynamics simulations across many decades of shear rates. Results demonstrate that the molecular weight of the polymer plays a key role in determining the critical shear rate, whereas the concentration of polymer primarily affects the Newtonian viscosity. The simulations are further used to show the molecular origins of shear thinning and critical shear rate. The atomistic simulations and simple model developed in this work can ultimately be used to formulate polymer-enhanced fluids with ideal shear thinning profiles that maximize the efficiency of hydraulic systems. |
| first_indexed | 2024-03-10T14:35:22Z |
| format | Article |
| id | doaj.art-d26b30d9e6444c01a89000a5b20aef37 |
| institution | Directory Open Access Journal |
| issn | 2075-4442 |
| language | English |
| last_indexed | 2024-03-10T14:35:22Z |
| publishDate | 2020-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Lubricants |
| spelling | doaj.art-d26b30d9e6444c01a89000a5b20aef372023-11-20T22:15:22ZengMDPI AGLubricants2075-44422020-11-0181210210.3390/lubricants8120102Critical Shear Rate of Polymer-Enhanced Hydraulic FluidsPawan Panwar0Paul Michael1Mark Devlin2Ashlie Martini3Department of Mechanical Engineering, University of California Merced, 5200 N. Lake Road, Merced, CA 95343, USAFluid Power Institute, Milwaukee School of Engineering, 1025 N Broadway, Milwaukee, WI 53202, USAAfton Chemical, Richmond, VA 23218, USADepartment of Mechanical Engineering, University of California Merced, 5200 N. Lake Road, Merced, CA 95343, USAMany application-relevant fluids exhibit shear thinning, where viscosity decreases with shear rate above some critical shear rate. For hydraulic fluids formulated with polymeric additives, the critical shear rate is a function of the molecular weight and concentration of the polymers. Here we present a model for predicting the critical shear rate and Newtonian viscosity of fluids, with the goal of identifying a fluid that shear thins in a specific range relevant to hydraulic pumps. The model is applied to predict the properties of fluids comprising polyisobutene polymer and polyalphaolefin base oil. The theoretical predictions are validated by comparison to viscosities obtained from experimental measurements and molecular dynamics simulations across many decades of shear rates. Results demonstrate that the molecular weight of the polymer plays a key role in determining the critical shear rate, whereas the concentration of polymer primarily affects the Newtonian viscosity. The simulations are further used to show the molecular origins of shear thinning and critical shear rate. The atomistic simulations and simple model developed in this work can ultimately be used to formulate polymer-enhanced fluids with ideal shear thinning profiles that maximize the efficiency of hydraulic systems.https://www.mdpi.com/2075-4442/8/12/102hydraulicsfluidcritical shear rateonset of shear thinningpolymermolecular dynamic simulation |
| spellingShingle | Pawan Panwar Paul Michael Mark Devlin Ashlie Martini Critical Shear Rate of Polymer-Enhanced Hydraulic Fluids Lubricants hydraulics fluid critical shear rate onset of shear thinning polymer molecular dynamic simulation |
| title | Critical Shear Rate of Polymer-Enhanced Hydraulic Fluids |
| title_full | Critical Shear Rate of Polymer-Enhanced Hydraulic Fluids |
| title_fullStr | Critical Shear Rate of Polymer-Enhanced Hydraulic Fluids |
| title_full_unstemmed | Critical Shear Rate of Polymer-Enhanced Hydraulic Fluids |
| title_short | Critical Shear Rate of Polymer-Enhanced Hydraulic Fluids |
| title_sort | critical shear rate of polymer enhanced hydraulic fluids |
| topic | hydraulics fluid critical shear rate onset of shear thinning polymer molecular dynamic simulation |
| url | https://www.mdpi.com/2075-4442/8/12/102 |
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