Prediction of water solubility in nylon melts based on flory‐huggins theory

Abstract

The solubility of water in molten aliphatic polyamides (nylons) of high degrees of polymerization at conditions of subatmospheric water partial pressure and high temperature (225 to 3OOOC) has been modeled. A simple, semi-empirical model based on Flory-Huggins theory was fit to the available literature data for nylons 6, 66, 610 and 11 and to new experimental data for nylon 612. The model contains only two fitted parameters, and is able to adequately describe the available data for the effects of temperature and nylon type on the water concentration in the melt at various water partial pressures. INTROXBUCTION method involving coulometric regeneration of P,O, (8).olymndensation of nylons is an equilibrium-limited

Grand canonical ensemble molecular dynamics simulation of water solubility in polyamide-6,6

“…5 and are compared with experiment. 50,51,53 A comparison of the calculated solubility coefficients with experiment 50,51,53 shows that there is a good agreement between our calculated values and experimental data. Former studies on the simulation of solubility of gases in polymers show similar differences between experimental and computed solubility coefficients.…”

“…A comparison of our calculated sorption isotherms and solubility coefficients of water in PA-6,6, over a wide range of temperatures and pressures, with experiment shows that the results are in good agreement with experiment. 50,51,53 Although our calculated solubilities of water in PA-6,6 are higher than the experimental data, such deviations are quite acceptable for solubility calculations in polymers. Our calculations show that the calculated heat of sorption of water in PA-6,6, 39.66 kJ mol À1 , well agrees with the experimental value, 40.66 kJ mol À1 .…”

“…2 at 550 K. comparable with a value of 40.66 kJ mol À1 , calculated based on the experimental data of solubility coefficients. 50,51,53 Conclusions Grand canonical ensemble MD simulation technique 32 is employed to calculate the densities of water in PA-6,6 and gaseous phases, corresponding to the target values of the excess chemical potential, temperature, and volume. It is shown that two independent simulations are needed to calculate the phase coexistence point.…”

Polycondensation

“…The activity of water can be directly measured from knowledge of its vapor pressure, and it has been claimed that a correlation based upon a Flory-Huggins model can predict it [190], but no model exists for taking into account the group interactions. It obviously changes the activity coefficients of functional groups, but no thermodynamic model has ever been used to completely describe the mixture.…”

Mathematical Modeling of Nylon 6/6,6 Copolymerization: Beneficial Influence of Comonomers on Degree of Polymerization in Batch Reactor

“…Appropriate values of k w A s for use in mathematical models depend on the type and size of reactor and agitator, the agitation speed, reactor geometry and physical properties of the liquid phase. Henry's law, Raoult's Law and Flory‐Huggins‐based correlations have been used to calculate [ W ] eq and similar equilibrium concentrations for caprolactam and HMD …”