Molecular Dynamics Simulation Compatibility of Poly(vinyl Alcohol) as a Plasticizer Anti-Migration Liner in the Presence of Nitrate Esters

Hypothesis: Molecular dynamics simulation is a powerful computational technique for studying and predicting the time evolution of physical systemsat the atomic level, which simulates the trajectory of atoms over time by numerically solving Newton's equations of motion. Molecular dynamics simulation is an efficient method to reduce the time, cost, and risks associated with working with high-energy materials. Therefore, molecular dynamics simulation of the compatibility and migration of plasticizers in liners, binders, and adhesives used in propellants can reveal many of their properties before functional tests
Methods: In this research, polyvinyl alcohol was studied as a new liner in the presence of high-energy nitrate ester plasticizers such as 1,2,4-butanetriol trinitrate (BTTN) trimethylolethane trinitrate (TMETN), and triethylene glycol dinitrate (TEGDN), and its anti-migration properties were investigated. Molecular dynamics simulation of polyvinyl alcohol in the presence of 10% plasticizer was performed based on NPT and Compass III force field, with a standard deviation of less than 5%, as well as the binding energy, radial distribution function, and solubility parameter were calculated 
Findings: The PVA/TEGDN mixture had the highest binding energy and showed the best compatibility. Also, the solubility parameter of polyvinyl alcohol and TEGDN had the least contrast and the highest miscibility, and in other samples the miscibility decreased. The intermolecular radial distribution function showed that the interactions of the studied mixtures were of the strong van der Waals type, and compatibility was observed in these mixtures. To validate the results, a vacuum stability test was used. Polyvinyl alcohol showed the highest compatibility in the presence of all three plasticizers. The PVA/TEGDN mixture with the lowest volume of gas released (3.185 mL) showed the highest compatibility. It was determined that polyvinyl alcohol can be used as a liner with the ability to absorb nitrate ester plasticizers.