ARS | Publication request: Development of an environmentally friendly halogen-free phosphorous-nitrogen bond flame retardant for cotton fabrics

Submitted to: Polymers for Advanced Technologies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 12, 2011
Publication Date: N/A

Interpretive Summary: This research has been shown intumescent flame retardant for environmentally friendly halogen-free flame retardant which can be used to bring flame retardancy to cotton fabrics such as print cloth and twill. The combustible material is separated from the fire or heat source by insulating foams at the surface. Intumescent flame retardant system can be applied to decrease flammability of polymers. It is particularly useful to design and develop new environmentally friendly phosphorous and nitrogen containing flame retardant and formulations that enable textiles. Towards this goal novel compound was prepared via one single step synthesis and formulated in aqueous solutions to make print cloth and twill fabrics pass the 45° and vertical flammability tests. We achieved this ultimate result and in the process explained our design criteria, the chemistry to achieve the new compound, and employed standard test methods to verify our results. The new compound and their formulation will be of interest and use to professionals engaged in new materials designing in textile industries to create new marketable uses for cotton fibers and fabrics to serve emerging needs.

Technical Abstract: A novel flame retardant Diethyl 4-methylpiperazin-1-ylphosphoramidate, CN-3, containing phosphorous and nitrogen was prepared. Its chemical structure was confirmed by nuclear magnetic resonance (1H, 13C, 31P NMR), Fourier transform infrared spectrometry (FTIR), and elemental analysis. Print cloth and twill fabrics were treated with CN-3 to achieve different levels of add-on (7-22 wt% add-ons for print cloth and 3-18 wt% add-ons for twill). Thermogravimetric Analysis (TGA), vertical flame test and limiting oxygen index (LOI) were performed on the treated cotton fabrics and showed promising results. When the treated print cloth and twill fabric samples were tested using the vertical flame test (ASTM D6413-08), we observed that the ignited fabrics self extinguished and left behind a streak of char. Treated higher add-ons fabrics were neither consumed by flame, nor produced glowing ambers upon self extinguishing. Limiting oxygen index (LOI, ASTM 2863-09) was utilized to determine the effectiveness of the flame retardant on the treated fabrics. LOI values increased from 18 vol% oxygen in nitrogen for untreated print cloth and twill fabrics to maximum of 28 and 31 wt% for the highest add-ons of print cloth and twill, respectively. The results from cotton fabrics treated with CN-3 demonstrated a higher LOI value as well as higher char yield due to the effectiveness of phosphorus and nitrogen as a flame retardant for cotton fabrics. Furthermore, FT-IR and SEM were employed to characterize the chemical structure on the treated fabrics as well as the surface morphology of char areas of treated and untreated fabrics.