(540d) Growth and Intumescent Flame Retartdant Behavior of Multilayer Thin Films Prepared From Completely Renewable Charged Polymers and Molecules

In an effort to reduce flammability of cotton fabric, which is the most used natural textile, environmentally-friendly flame retardant system was assembled using “green” materials obtained from renewable sources. Cationic chitosan (derived from crustacean shells) and anionic phytic acid (major phosphorus storage molecule in plants) were deposited onto cotton fabric via layer-by-layer (LbL) assembly. These films grow linear as a function of bilayers deposited, growing most effectively with both ingredients at pH 5. Fabric structure and integrity was highly preserved following vertical flame testing.  In some cases, no ignition occured (i.e., the fabric did not burn when exposed to direct flame).  Postburn analysis of coated fabric revealed significant bubble formation on fibers with SEM imaging. Cone calorimetry shows that peak heat release rate and total heat release has 60 % and 76 % reduction, respectively, compared to the uncoated fabric, with 30 BL of CH-PA coating. This study marks the first fully renewable intumescent nanocoating to dramatically reduce the flammability of cotton.