Investigating the glass transition temperature at the atom-level in select model polyamides: A molecular dynamics study

Abstract

The molecular influence on glass transition temperature (T g ) of select model polyamides was investigated by atomistic modeling. These include nylon 6,6, nylon 6,12, a cycloaliphatic polyamide consisting of 4,4'-methylene-bis(cyclohexylamine) and dodecanedioic acid, as well as a corresponding aromatic counterpart consisting of 4,4'-methylenedianiline and dodecanedioic acid. For each model system, all-atom atomistic molecular dynamics simulations were used to discern and differentiate parameters such as free volume, hydrogen bonding, and chain rigidity. Simulations were able to predict the correct trend in T g , where the model cycloaliphatic polyamide was shown to have the highest T g followed by the aromatic polyamide. This is presumably due to the greater chain rigidity exhibited by the cycloaliphatic polyamide around the cyclohexyl ring, which was revealed through a calculation of the dihedral rotation free energy barrier associated with the methylene moiety between either the bis-cyclohexyl or bisphenyl rings, despite the former having a higher extent of free volume.

Quantitative relationships between intermolecular interaction and damping parameters of irganox‐1035/NBR hybrids: A combination of experiments, molecular dynamics simulations, and linear regression analyses

“…The short chains may result in end effects, while the long chains may be out of the calculation ability of the computer . Here a molecular chain with 50 repeating units, which is long enough to show the movements of segments, density and solubility parameter of NBR, was chosen.…”

“…In general, molecular simulation can be divided into molecular mechanics (MM), Monte Carlo (MC) methods, and molecular dynamics (MD) simulations . Mimicking real systems as much as possible, MD simulation is a powerful theoretical tool to understand the microstructure–property relationships . For example, Tanya et al .…”

Glass transition in single poly(ethylene oxide) chain: A molecular dynamics simulation study

“…In early 1990s, it was demonstrated that the Volume‐Temperature curves obtained from molecular dynamics (MD) simulations could be used to locate volumetric T g of simple polyolefin . Until now, this strategy has been extensively validated against many complex polymers, such as polycyanurates, polyamides, epoxy resins, etc. Furthermore, effects of various factors (i.e.…”

Natural Rubber with Polyhedral Oligomeric Silsesquioxane, Nanocomposites, and Hybrids Compared by Molecular Modeling

“…Diagrams of density versus temperature were used to calculate the glass transition temperatures and other thermal transitions. We found that second-degree polynomials better described the density between thermo-mechanical transitions rather than a linear correlation, the latter being the correlation most used in the literature, [36][37][38][39][40]19] the latter is true for the topology method where the correlation coefficient (R 2 ) was equal to 1.000.…”