Molecular dynamics insight to phase transition in n-alkanes with carbon nanofillers

Abstract

The present work aims to investigate the phase transition, dispersion and diffusion behavior of nanocomposites of carbon nanotube (CNT) and straight chain alkanes. These materials are potential candidates for organic phase change materials(PCMs) and have attracted flurry of research recently. Accurate experimental evaluation of the mass, thermal and transport properties of such composites is both difficult as well as economically taxing. Additionally it is crucial to understand the factors that results in modification or enhancement of their characteristic at atomic or molecular level. Classical molecular dynamics approach has been extended to elucidate the same. Bulk atomistic models have been generated and subjected to rigorous multistage equilibration. To reaffirm the approach, both canonical and constant-temperature, constant- pressure ensembles were employed to simulate the models under consideration. Explicit determination of kinetic, potential, non-bond and total energy assisted in understanding the enhanced thermal and transport property of the nanocomposites from molecular point of view. Crucial parameters including mean square displacement and simulated self diffusion coefficient precisely define the balance of the thermodynamic and hydrodynamic interactions. Radial distribution function also reflected the density variation, strength and mobility of the nanocomposites. It is expected that CNT functionalization could improve the dispersion within n-alkane matrix. This would further ameliorate the mass and thermal properties of the composite. Additionally, the determined density was in good agreement with experimental data. Thus, molecular dynamics can be utilized as a high throughput technique for theoretical investigation of nanocomposites PCMs.

Rational molecular dynamics scheme for predicting optimum concentration loading of nano-additive in phase change materials

“…atomistic models (not shown here). The peak diminishing or weakening in pristine docosane model 18 is much inferior to that achieved through surface functionalized SWCNT and GO based atomistic model. This gives a clear indication of ameliorated thermal response of the nano-additive based composites.…”

“…[13][14][15][16][17] First paper described the role of MD in assimilation of microscopic mechanisms occurring during the phase transition of nanocomposites based on paraffin hydrocarbons reinforced with single walled carbon nanotubes. 18 Self-diffusion coefficient of the various atomistic models exhibited the interaction between the particles as a function of temperature, with variation in CNT loading. Moreover, the diminishing peaks of radial distribution function curves further demonstrated the quick thermal response, due to addition of CNTs.…”