Dyeing of polyester fabrics based on a liquid paraffin system: thermodynamic, kinetic, and molecular dynamics simulation studies

Dyeing using liquid paraffin (LP) systems is an emerging non-aqueous dyeing method for disperse dyes. To investigate the dyeing thermodynamics and kinetics of polyester fabrics dyed with disperse dyes (C.I. Disperse Red 167) in an LP system, the adsorption isotherms and dyeing rate curves in a water bath and a LP bath were plotted. Next, a molecular dynamics (MD) simulation model was constructed. The results showed that the adsorption isotherms and dyeing rate curves in the LP bath and the water bath had the same shape and trend, and the isotherms were consistent with the Nernst isotherm equation. The dyeing affinity of disperse dyes in the LP bath was smaller than that in water bath, due to the higher solubility of disperse dyes in LP than in water. The dyeing heat, dyeing entropy, dyeing rate constant, and apparent diffusion coefficient of disperse dyes in LP bath showed the same sign and similar change trend as those in water bath. The diffusion activation energy of disperse dyes in LP bath was higher than that in water bath, indicating more energy consumption required in LP bath than in water bath. The system of dyeing polyester with disperse dyes in LP bath was investigated at the atomic level by using MD simulations, and the results confirmed the accuracy and reliability of the constructed dyeing models.