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Title: The thermal degradation pathway studies of a phosphazene derivative on cotton fabric

item Fontenot, Krystal
item Nguyen, Monique
item AL-ABDUL-WAHID, M. SAMEER - Miami University - Ohio
item Easson, Michael
item Chang, Sechin
item LORIGAN, GARY - Miami University - Ohio
item Condon, Brian

Submitted to: Industrial and Engineering Chemistry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2015
Publication Date: 5/22/2015
Citation: Fontenot, K.R., Nguyen, M.M., Al-Abdul-Wahid, M., Easson, M.W., Chang, S., Lorigan, G.A., Condon, B.D. 2015. The thermal degradation pathway studies of a phosphazene derivative on cotton fabric. Industrial and Engineering Chemistry Research. 120:32-41.

Interpretive Summary: There is a growing interest in understanding the thermal behavior, flammability properties, and degradation behavior of flame retardants. Studying the thermal degradation of a FR provides information in reference to the products produced in the vapor and condensed phase that retard fire. Mechanism studies of flame retardants in general are limited; a small number of studies focus on phosphazene-derived flame retardants for polymeric systems with an even smaller scope on phosphazene derivatives as an inherent flame retardant for cotton fabric. The phosphazene derivative 1,1,3,3-dihydroxybiphenyl-5,5-diaminoethanephosphazene (dBEP) has been investigated for its thermal behavior and flammability properties as an effective flame retardant for cotton textiles. With a low add-on value, dBEP has a low onset temperature of degradation, a high char yield, and a high limiting oxygen index value. To better understand the thermal degradation of a phosphazene derivative on cotton textiles, dBEP was grafted onto cotton fabric and investigated using a combination of techniques. TGA-FTIR was employed to examine the gas phase and attenuated total reflectance infrared (ATR-IR) and solid state high power proton decoupling with magic angle spinning nuclear magnetic resonances (HPPD/MAS-NMR) was employed study the solid phase. This combination of techniques established the degradation pathway of a phosphazene-derived flame retardant on cotton fabric. The control fabric, treated fabric, and dBEP were investigated to determine the thermal degradation of dBEP on cotton fabric. The FTIR reflects the TGA profile of the broad and sharp decent for the control and treated fabric, respectively. Solid state HPPD/MAS-NMR, ATR-IR, and TGA support the thermal decomposition of dBEP through structural assignment, functional groups, and onset temperatures. dBEP decomposes to produce amino and aromatic substances in the gas phase and phosphoric acid and phospham-like product in the solid phase. These products are likely to account for the flame retardant behavior, high char yield and high limiting oxygen index value. The novelty of this phosphazene-based flame retardant is based on three of the four nitrogen atoms surrounding phosphorus that resembles a phospham-like structure. This work provides insight into the products that are released during the thermal degradation of a phosphazene derivative on cellulose cotton twill fabric.

Technical Abstract: Phosphazene derivatives have been recognized as promising flame retardants for numerous polymeric systems. However, limited studies are available for phosphazene derivatives on cotton fabric. In this study, a phosphazene derivative 1,1,3,3-dihydroxybiphenyl-5,5-diaminoethanephosphazene (dBEP) was synthesized and the thermal degradation pathway of cotton fabric treated with dBEP was investigated. Thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TGA-FTIR) was used to study the evolved gases produced by the control and treated fabrics. Two techniques attenuated total reflectance spectroscopy (ATR-IR) and solid state nuclear magnetic resonances (NMR) were employed to study the degraded residues of the unburned and burned fabrics and dBEP. The results showed that dBEP undergoes decomposition to produce phosphate, phosphonate, and phospham-like derivatives that are known to retard fire.