Molecular Dynamics Simulation for the diffusion of water in amorphous polymers examined at different Temperatures

The authors first investigate a polymeric composite material ( epoxy resin with silicone nanoparticles) and determine its mechanical properties (coefficient of thermal expansion-CTE and Young´s Modulus-E) by a combined experimental and simulative (homogenisation) approach. The size distribution and the volume fraction percentage of the nanoparticles were determined as well as the variation of the mechanical properties of the pure epoxy resin compared to the composite material especially synthesized for this investigation. Then the diffusion coefficient of water in amorphous polymeric materials is measured (aromatic epoxy: 1,3-Bis-(2,3- epoxypropyl)-benzene and amine hardener: 1,2- Diaminoethan). Mechanical characterization of the materials, diffusion experiments (gravimetric), and molecular dynamics (MD) simulations examine the temperature range of 300-400 K, where diffusion coefficients will be calculated under thermodynamic boundary conditions by using a classical force-field MD. The diffusion mechanisms and the mechanical characterization are examined as a function of the stoichiometry and molecular weight of the polymers.