Relationship between chemical structure and dyeing performance of PA56 fabrics in a nonaqueous medium continuous dyeing system

Purpose The purpose of this paper is to investigate the correlation between the chemical structure of reactive dyes and the dyeing performance of polyamide 56 (PA56) fabrics in a nonaqueous medium continuous dyeing system. Design/methodology/approach The nonaqueous medium [decamethylcyclopentasiloxane (D5)] was used as the fixation medium to realize the coloration of PA56 fabrics. To optimize the dyeing performance of reactive dyes on PA56 fabrics, reactive dyes with diverse structures were selected to dye PA56 fabrics. Parameters, such as the coplanarity, polarity and volume of each dye molecule, were quantified via Gaussian calculations. Meanwhile, the relationship between the dyeing performance of PA56 fabrics and structures of reactive dyes was evaluated by analyzing dye fixation and color fastness. Furthermore, the dyeing thermodynamics were investigated. Findings The results indicated that the dyeing performance of dyes improved with the polarity and coplanarity of dye molecules increasing. While the molecular volume, reactive groups and water-soluble groups were negatively correlated with their dyeing properties on the PA56 fabrics. The ranking of influencing factors was as follows: polarity > coplanarity > volume > number of reactive groups > number of water-soluble groups. Originality/value This study provides a theoretical basis for the rapid selection of reactive dyes for dyeing PA56 fabrics.