APPLICATION OF THE MOLECULAR SIMULATION TECHNIQUE TO CHARACTERIZE THE STRUCTURE AND PROPERTIES OF AN AROMATIC-POLYSULFONE SYSTEM .2. MECHANICAL AND THERMAL-PROPERTIES

The structure of aromatic amorphous polysulfone was simulated and the energy and internal strain minimized by using molecular dynamics and mechanics methods developed earlier. A plot of the total potential energy as a function of volume or density indicates the existence of an optimum state possessing both the lowest energy and the least internal stress. The minimum-energy structure has a computed density of 1.17 +/- 0.02 g/cm3, in good agreement with the experimental value. The mechanical and thermal properties of amorphous polysulfone were simulated using these model amorphous structures. The form of the stiffness matrix and the calculated associated elastic constants agree with known values for such an isotropic amorphous polymer. The thermal expansion coefficient calculated using molecular dynamics also agrees with the experimental value.