Molecular Dynamics Simulation of the Stress–Strain Behavior of Polyamide Crystals

Molecular dynamics simulations were used to model aramid poly(p-phenylene terephthalamide) (PPTA) and a related aromatic–aliphatic polyamide derived from five-carbon aliphatic diacid (PAP5) with nine different reactive nonreactive force fields. The fields evaluated based on crystal structures as well intermolecular H-bonding ?-? interactions. An optimum field was then simulate the stress–strain behavior in chain transverse-to-chain directions. In direction, PAP5 had higher ultimate stress failure strain than PPTA; however, stiffness of lower that PPTA at low (0–2%), while reverse observed high (last 5% before failure). This contrast differences transverse direction properties explained by methylene segments confer conformational freedom, enabling accommodation without stretching covalent bonds. simulation approach demonstrated here for two polymers distinct chemistry but similar atomic interactions may be extended other polyamides.