Layer By Layer Assemblies For Enhancing Flame

This work aims to demonstrate the feasibility of the Layer by Layer technique as a “green” and simple process for enhancing the flame retardancy of cotton fabrics.The layer by layer process, invented by Iler in 1966 allows obtaining self-assembled coatings on different substrates(like plastics, metals, paper, textiles); it is quite a sustainable approach, since the solvent used for the assembly is deionized water and the solutions/dispersions of the employed polyelectrolytes are very diluted(usually at 1 wt.%).Layer by Layer consists of an alternate deposition of oppositely-charged solutions/dispersions of polyelectrolytes, where electrostatic interactions can be exploited for the building up of a nanostructured coating on the chosen substrate.Flammability tests in horizontal configuration and cone calorimetry measurements have been used for assessing the fire behavior of the treated textiles as compared to the neat fabric. Flammability tests revealed that LbL is effective in delaying the burning of the fabrics, increasing the burning time and decreasing the burning rate.Cone calorimetry tests showed some improvements since an increase of time to ignition, as well as a decrease of the peak of the heat release rate was assessed. The residues after cone calorimetry tests of the LbL-treated fabrics were found coherent and consistent, unlike neat cotton. Furthermore, a significant decrease of the smoke generated was found for the LbL-treated fabrics.One of the main drawbacks of the LbL treatments used in the present work can be referred to their durability to washing treatments, even after exposure to UV radiation, since washing promoted a partial removal of the coating, hence lowering the final fire performances of the fabrics.