Preparation and characterization of cationic dyeable polycaprolactam modified with 5-sulfoisophthalic acid sodium and poly(ethylene glycol)

Abstract

Unmodified nylon is dyeable to a single color only, and is almost exclusively dyed with acid dyes that are absorbed with amine groups of nylon molecules. Two types of polycaprolactam (PA6) copolyamide were successfully prepared with 5-sulfoisophthalic acid monosodium salt and poly(ethylene glycol) (PEG) units named cationic dyeable polyamide (CD-PA6) and easy cationic dyeable polyamide (ECD-PA6). The chemical and crystalline structures of CD-PA6 and ECD-PA6 were characterized by Fourier transform infrared spectroscopy and wide angle x-ray diffraction, and their thermal properties were tested by differential scanning calorimetry and thermogravimetric analysis, respectively. In addition, the rheological behavior and mechanical properties of copolyamide are presented in this paper. The influence of chemical modification in polyamide 6 fibers on the dyeing properties was investigated using cationic dye (methylene blue). The incorporation of PEG not only destroyed the regularity of the molecular chain arrangement and created more amorphous regions of ECD-PA6 samples, but also led to nylon 6 changing from the α-form to the γ-form. In addition, the crystallinities and degradation temperatures of samples which corresponded to different mass losses of CD-PA 6 and ECD-PA6 declined as the sulfonic group content increased, since large –SO3Na side groups in the copolymers prevented the chain molecules from tightly coagulating and obstructed the formation of larger crystals. Based on the analysis of the dyeing, a distinct improvement in tinctorial affinity and wash fastness for modified fibers compared with unmodified fibers was revealed.

Preparing cationic dyeable polyamide 6 filaments by combining the masterbatch technique with melt copolymerization

“…The dye uptake ( A ) formula is calculated as in (5) 10 where A i is the absorbance of the solution after dyeing; A 0 is the absorbance of the remaining solution before dyeing; and N 0 , N i are the dilution times.…”

“…The carboxyl terminal structure at both ends of 5-SSIPA will inevitably destroy the molar balance between the amino group and the carboxyl group in the system, thereby producing the end-capping effect. 22 Xiong and Yin 10 introduced 5-SSIPA into PA6 by copolymerization, but the end-capping effect made its molecular weight unable to be effectively guaranteed. The obtained chips could not be processed by melt spinning, which affected its wider application.…”

Preparation, Characterization, and Desolvation of 5‐Sulfoisophthalic Acid Sodium Salt Solvates

“…5-Sulfoisophthalic acid sodium salt (5-SSIPA) as an intermediate and modifier has been applied and developed in many fields, such as pharmaceuticals, pesticides, and polyesters [20][21][22]. The fact that both carboxyl and sulfonic groups in the structure of 5-SSIPA can form compounds with sodium ions make the crystal form of 5-SSIPA with low stability [23,24].…”