Intrinsic intumescent-like flame retardant properties of DNA-treated cotton fabrics.

In the present work, the effect of different DNA add-ons (namely, 5, 10 and 19 wt.%) has been thoroughly investigated as far as the flammability and the resistance to an irradiating heat flux of 35 or 50 kW/m(2) are considered. The results have shown that 10 wt.% is the minimum amount that allows reaching the self-extinguishment of cotton when a methane flame is applied. Furthermore, only 19 wt.% is able to confer resistance to the fabric towards an irradiating heat flux of 35 kW/m(2): indeed, the specimens tested under the cone calorimetry do not burn. Measurements of temperature runs as a function of time have clearly indicated that cotton, instead of burning, pyrolyses: indeed, because of the protective role exerted by DNA molecules, the deposited coatings have turned out to absorb heat, form char and induce its formation on the fabric, and finally to release inert gases.