Measurement and prediction of kinematic viscosity for linear ethers
Nicholas T Liesen1, Gabriel A Palermo2, Isamu Kusaka1
1William G. Lowrie Department of Chemical and Biomolecular Engineering, Koffolt Laboratories, The Ohio State University, CBEC, 151 W. Woodruff Avenue, Columbus, Ohio 43210-1350, USA.
The Journal of Chemical Physics
|July 17, 2020
Summary
Molecular dynamics simulations and experiments reveal differences between united and all-atom models for linear ethers. Both models show increased orientational alignment at lower temperatures, impacting viscosity and diffusion predictions.
Area of Science:
- Computational chemistry
- Physical chemistry
- Materials science
Background:
- Accurate molecular modeling is crucial for predicting material properties.
- Linear ethers are important in various chemical applications, requiring precise property prediction.
- Understanding the nuances of different atomic models (united vs. all-atom) is key for simulation accuracy.
Purpose of the Study:
- To compare the predictive capabilities of united and all-atom models for linear ethers.
- To investigate the influence of temperature and shear rate on viscosity and diffusion.
- To analyze the relationship between molecular dynamics, relaxation times, and transport properties.
Main Methods:
- Equilibrium and non-equilibrium molecular dynamics simulations.
- Capillary viscometer experiments.
- Analysis using rotational relaxation times and the Arrhenius equation.
Main Results:
- Both models exhibited increased orientational alignment with decreasing temperature.
- Consistent differences in activation energies were observed between models and experimental data.
- A direct correlation was found between viscosity, rotational relaxation time, and diffusion time.
Conclusions:
- The choice of atomic model (united vs. all-atom) significantly affects predicted properties of linear ethers.
- Rotational relaxation times are critical for understanding and accurately predicting viscosity, including Green-Kubo results.
- Force field performance varies with chain length, necessitating careful selection for specific applications.
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