International Journal of Materials Science and Applications 2017; 6(6): 269-276 http://www.sciencepublishinggroup.com/j/ijmsa doi: 10.11648/j.ijmsa.20170606.11 ISSN: 2327-2635 (Print); ISSN: 2327-2643 (Online) Preparation of Flame Retardant Cotton Fabric Using Environmental Friendly Supercritical Carbon Dioxide Sechin Chang * , Brian Condon, Jade Smith, Michael Easson Department of Agriculture, Agricultural Research Service - Southern Regional Research Center, New Orleans, USA Email address: sechin.chang@ars.usda.gov (S. Chang), brian.condon@ars.usda.gov (B. Condon), jade.smith@ars.usda.gov (J. Smith), michael.easson@ars.usda.gov (M. Easson) * Corresponding author To cite this article: Sechin Chang, Brian Condon, Jade Smith, Michael Easson. Preparation of Flame Retardant Cotton Fabric Using Environmental Friendly Supercritical Carbon Dioxide. International Journal of Materials Science and Applications. Vol. 6, No. 6, 2017, pp. 269-276. doi: 10.11648/j.ijmsa.20170606.11 Received: August 21, 2017; Accepted: September 6, 2017; Published: October 16, 2017 Abstract: Due to its environmentally benign character, supercritical carbon dioxide (scCO 2 ) is considered in green chemistry, as a substitute for organic solvents in chemical reactions. In this paper, an innovative approach for preparation of flame retardant cotton fabric was obtained by utilizing supercritical carbon dioxide with co-solvent. A novel phosphorus- nitrogen containing piperazine derivative, tetraethyl piperazine-1,4-diyldiphosphonate (pdp) and a sulfur-nitrogen containing derivative, tetramethyl piperazine-1,4-diyldiphosphonothioate (pdpt) were synthesized, and their chemical structures were confirmed by nuclear magnetic resonance ( 1 H and 13 C NMR) and elemental analysis. pdp and pdpt were then used to treat cotton fabric processed in scCO 2 . Thermogravimetric analysis (TGA), vertical flame test (ASTM D6413-08), and limiting oxygen index (LOI, ASTM D2863-09) were performed on the treated cotton fabrics, and showed promising results. When the treated fabrics were tested using the vertical flame, we observed that the ignited fabrics self extinguished and left behind a streak of char. Treated higher add-on fabrics were neither consumed by flame, nor produced glowing ambers upon self extinguishing. The results from cotton fabrics treated with new phosphorus-nitrogen containing piperazine derivatives demonstrated a higher LOI value as well as higher char yields due to the effectiveness of phosphorus and nitrogen as a flame retardant for cotton fabrics. Furthermore, SEM was employed to characterize the chemical structure on the treated fabrics as well as the surface morphology of char areas of treated and untreated fabrics. Keywords: Cotton Fabric, Flame Retardant, Supercritical Carbon Dioxide, Flame Test 1. Introduction Consumption of cotton is encouraged in a variety of consumer markets because cotton is abundant, low in cost, appealing to consumers, and is a versatile starting material for new product development. However, cotton is readily attacked by flame, microbes, and insects, and requires chemical modification for resiliency. In this paper, we will focus on making cotton fabrics resistant to attack by flame. Phosphorus-containing compounds for flame retardants are widely used in the textile industry to make cotton textiles flame resistant [1]. Phosphorus-containing flame retardant compounds have been chemically reacted with cotton, producing products with an ether cross linker between the phosphorus compound and the cellulosic material. In condense phase, the phosphorus containing functional groups are converted by thermal decomposition to phosphoric acid, forming a protective char. Char development and intumescences provide low flammability to cotton textiles [2, 3]. Nitrogen-containing flame retardants in combination with phosphorus compounds have multifunctional advantages: 1) low toxicity during combustion, 2) high efficiency measured by cone calorimeter, and 3) low smoke development in fire accidents [4]. Some nitrogen containing compounds such as urea, dicyandiamide, and melamine will accelerate phosphorylation of cellulose through formation of a