Submitted to: Fibers and Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2012
Publication Date: 10/1/2012
Citation: Nguyen, M.M., Chang, S., Condon, B.D., Slopek, R.P. 2012. Synthesis of a novel flame retardant containing phosphorus-nitrogen and its comparison for cotton fabric. Fibers and Polymers. 13(8):963-970.
Interpretive Summary: It is mainly useful to design and develop novel environmentally friendly small molecules and formulations that allow textiles of commerce to be flame resistant. Towards this goal two novel compounds were prepared via short two-step syntheses, and formulated in aqueous solutions to make twill fabrics pass the 45º angle flammability test. We achieved this ultimate result and in the process explained our design criteria, the chemistry to achieve the new compounds, and employed standard test methods to verify our results. The new compounds and their textile formulations will be of interest and use to professionals engaged in new materials designing in textile industries to create new marketable uses such as firefighter apparel, institutional draperies and upholstery, carpet, transportation blankets and seat covers, children’s sleepwear, and bedding etc.
Technical Abstract: A new charring agent, a derivative of cyanuric chloride, mono-substituted, dimethyl (4,6-dichloro-1,3,5-triazin-2-yloxy)methylphosphonate (CN), was synthesized in good yield and characterized by 1H, 13C, and 31P nuclear magnetic resonance spectroscopy (NMR), elemental analysis, and gas chromatography mass spectrometry (GC-MS). Its flame retardant and thermogravimetric properties were compared to those of the di-substituted compound, tetramethyl (6-chloro-1,3,5-triazine-2,4-diyl)bis(oxy)bis(methylene)diphosphonate (CN-1), which was prepared in previous work. All untreated fabric showed limiting oxygen index (LOI) values of about 18 vol% oxygen in nitrogen. Fabrics treated with CN at 5-21 wt% add-ons had high LOI values of 30-40 vol%, while fabrics treated with CN-1 at 5-19 wt% add-ons had low to high LOI value of 20-36 vol%. In 45º angle flammability tests, all treated fabrics with CN and CN-1 were designated class 1 by having an average time of flame spread in the test of more than 3.5 seconds or not igniting at all. Thermal degradation revealed that onset of degradation and the char yield of CN compound is higher than that of CN-1. Treated fabric with CN, 21 wt% add-on, had an onset of degradation of 240ºC, while CN-1 treated fabric 19 wt% add-on displayed an onset of degradation of 230ºC. Despite the differences in onset temperature, the two samples provided the same char yield in both conditions (~35 and ~13 %) at 600ºC. With Fourier transform infrared (FTIR), samples of treated/unburned and treated/burned of CN and CN-1 showed the same functional groups and revealed the disappearance of triazine group and P-O-methyl after burning. Additionally, scanning electron microscopy (SEM) showed that both CN and CN-1 acted as flame retardants by the same mechanism and characterized the surface morphology of the flame retardant treated twill fabrics.