A durable flame retardant with N-P=O(O-NH4+)2 based on amino acid for cotton fabrics

The ammonium salt of glycine phosphamide phosphoric acid (AGPP), a highly durable bio-based flame retardant with N- P=O(O-NH4+)2, was synthesized without formaldehyde for cotton fabrics (CF). It was attached to CF by forming P-O-C with cellulose. The p-& pi; conjugation of N and P=O made N- P(=O)- O- C very stable, so P-O-C was difficult to hydrolyze even during high-intensity washing, which greatly improved the launderability of treated CF. The limiting oxygen index of 25 wt% AGPP-treated CF was 51.6%, and only dropped to 43.9% after 50 laundering cycles performed following AATCC 61-2013 3 A standard (high temperature, intense machine wash). FT-IR and XPS results showed the presence of N-P and P-O-C bonds. TG, TG-FTIR, and residual char analyses implied that AGPP changed the degradation direction of CF and showed the condensed-phase flameretardant mechanism. SEM, XRD, and mechanical property tests showed that the morphology, crystal structure, and mechanical performance of the finished CF were well sustained.

Automated summary

A highly durable bio-based flame retardant, ammonium salt of glycine phosphamide phosphoric acid (AGPP), was synthesized without formaldehyde and attached to cotton fabrics by forming P-O-C bonds with cellulose. The conjugation of N and P=O in AGPP resulted in a stable structure, making it difficult to hydrolyze even during high-intensity washing, significantly improving the launderability of the treated cotton fabrics. The presence of N-P and P-O-C bonds was confirmed by FT-IR and XPS analysis. The treated cotton fabrics with 25 wt% AGPP showed a limiting oxygen index of 51.6%, which only dropped to 43.9% after 50 laundering cycles. TG, TG-FTIR, and residual char analyses indicated that AGPP altered the degradation direction of the cotton fabrics and exhibited a condensed-phase flame retardant mechanism. SEM, XRD, and mechanical property tests demonstrated that the morphology, crystal structure, and mechanical performance of the treated cotton fabrics were well maintained.