| Abstract: | Mechanical properties number themselves among the most important properties of any polymeric material used in engineering applications. The Molecular Mechanics approach has been used to calculate the mechanical moduli of various polymers, but this approach has the limitation of requiring experimental densities and neglecting both entropy contributions and local volume fluctuations which can be significant in condensed phase polymers such as glasses and melts. Although constant stress molecular mechanics can provide an estimate of the bulk density, constant stress molecular dynamics (CSMD) can overcome all these limitations. However, CSMD is limited by an inherently short simulation time scale. CSMD was used to calculate the bulk moduli, Young's moduli and density of various amorphous polymers, including: polyethylene, poly(propylene), polystyrene, poly(vinyl chloride), poly(ethylene terephthalate), poly(butylene terephthalate), nylon 6, poly(methyl methacrylate), polydimethylsiloxane, bisphenol-A polycarbonate, poly(phenylene sulfide). Results indicate that CSMD is a useful tool in characterizing mechanical properties of amorphous polymers despite this time scale limitation. |
