Three-Dimensional Cross-Linking Network Coating for the Flame Retardant of Bio-Based Polyamide 56 Fabric by Weak Bonds

• Published in: Polymers Vol. 16; no. 8; p. 1044
• Main Authors: Cui, Yunlong, Liu, Yu, Gu, Dongxu, Zhu, Hongyu, Wang, Meihui, Dong, Mengjie, Guo, Yafei, Sun, Hongyu, Hao, Jianyuan, Hao, Xinmin
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 10.04.2024; MDPI
• Subjects: Acids; Ammonia; Analysis; Bonding strength; Carbon; Char formation; Chemical bonds; Chemical processes; Coating; Coatings; Crosslinking; Fireproofing agents; flame retardant; Flame retardants; Fourier transforms; Hydrogen bonds; Mechanical properties; Melamine; Methods; Molecular chains; Nitrogen; polyamide 56 fabric; Polyamide resins; Polyamides; polyelectrolyte complex; Polyelectrolytes; Polyethyleneimine; Sodium; Sodium triphosphate; Synergistic effect; Textile fabrics; Thermal properties; Thermal stability; weak bond cross-linking; China; polyelectrolyte complex; flame retardant; weak bond cross-linking; polyamide 56 fabric; synergistic effect
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym16081044

Weak bonds usually make macromolecules stronger; therefore, they are often used to enhance the mechanical strength of polymers. Not enough studies have been reported on the use of weak bonds in flame retardants. A water-soluble polyelectrolyte complex composed of polyethyleneimine (PEI), sodium tripolyphosphate (STPP) and melamine (MEL) was designed and utilized to treat bio-based polyamide 56 (PA56) by a simple three-step process. It was found that weak bonds cross-linked the three compounds to a 3D network structure with MEL on the surface of the coating under mild conditions. The thermal stability and flame retardancy of PA56 fabrics were improved by the controlled coating without losing their mechanical properties. After washing 50 times, PA56 still kept good flame retardancy. The cross-linking network structure of the flame retardant enhanced both the thermal stability and durability of the fabric. STPP acted as a catalyst for the breakage of the PA56 molecular chain, PEI facilitated the char formation and MEL released non-combustible gases. The synergistic effect of all compounds was exploited by using weak bonds. This simple method of developing structures with 3D cross-linking using weak bonds provides a new strategy for the preparation of low-cost and environmentally friendly flame retardants.