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Computational material design of filled rubbers using multi-objective design exploration
Published in Alexander Lion, Michael Johlitz, Constitutive Models for Rubber X, 2017
M. Koishi, N. Kowatari, B. Figliuzzi, M. Faessel, F. Willot, D. Jeulin
For clarification of the mechanism and origin of mechanical properties of filled rubbers, numerical simulation of filled rubbers has been conducted in the past few decades. Recently, large-scale simulation using the model generated by 3D-TEM (transmission electron microtomography) was conducted by Akutawa et al. (2008) and Kadowaki et al. (2016) to compute effective material properties. Two-dimensional pattern reverse Monte Carlo analysis was performed to make structural model from the data obtained by time-resolved two-dimensional ultra-small angle x-ray scattering (Hagita et al. 2007 & Hagita et al. 2008). And to compute effective shear modulus, the complex multi-scale microstructure of filled rubber was generated numerically from a morphological model that was identified from statistical moments out of transmission electron microscopy images (Jean et al. 2011, for a simpler version).
Temperature and concentration effects on decyltrimethylammonium micelles in water
Published in Molecular Physics, 2019
Karen J. Edler, Daniel T. Bowron
Our initial study [9] of the atomistic structure of surfactant micelles formed in 0.4M C10TAB aqueous solutions at 25°C, used the Empirical Potential Structure Refinement (EPSR) methodology [10,11] where the experimental data is used as a constraint on the refinement of an atomistic model via a reverse Monte Carlo technique. This method has now been markedly improved by accessing parallel processing methods for the more computationally intensive aspects of the computer algorithms [12], making it feasible to investigate complex systems on a more routine basis. Current performance of EPSR, based on using a personal workstation running a 12 core Intel Xeon X5690 CPU at 3.47 GHz, typically allows us to refine atomistic models of systems containing 100000 atoms in approximately two weeks. System sizes with four times more atoms than in our initial model can now be run with a speed increase in which the larger model is delivered approximately ten times faster than the original which contained 26,304 atoms. These new data refinement capabilities allowed us to recently probe ion distributions around C10TAB micelles in solutions containing 0.4M C10TAB with 0.2M HCl or 0.2M HBr in water, and to compare these against ion distributions for the same micelles in pure water [8]. In the present paper, we compare the structure and counterion distributions around C10TAB micelles with our data at 25°C and 0.4M C10TAB with those found in solutions at 0.4M and 50°C or at 0.8M surfactant.