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.

Thermal stability and flame resistance of cotton fabrics treated with whey proteins

It is well described in the literature that whey proteins are able to form coatings, which exhibit high mechanical and oxygen barrier properties, notwithstanding a great water vapour adsorption. These peculiarities have been exploited for applying a novel protein-based finishing treatment to cotton and for assessing the protein effect on the thermal and thermo-oxidative stability and on the flame retardant properties of the cellulosic fabric. Indeed, the deposited whey protein coatings have turned out to significantly affect the thermal degradation of cotton in inert and oxidative atmosphere, and to somehow modify its combustion when a flame has been applied. Furthermore, the influence of the secondary and tertiary structure of these proteins on the morphology of the deposited coating, and thus on the thermal and flame retardant properties of the treated fabrics, has been evaluated by performing a denaturation thermal treatment before the protein application.

Polylactic acid and polylactic acid-based nanocomposite photooxidation

The importance of photooxidation in promoting formation of anhydride functional groups and thus promoting hydrolysis/biodegradation of polylactic acid and PLA nanocomposites were elucidated. PLA-based nanocomposites were prepared by adding 5% wt filler content of sodium montmorillonite (ClNa), sodium montmorillonite partially exchanged with Fe(III) (ClFe), organically modified montmorillonite (Cl20A), unmodified sepiolite (SEP), and fumed silica (SiO2). The pure PLA and nanocomposites were UV-light irradiated in artificial accelerated conditions representative of solar irradiation (λ > 300 nm) at 60 °C in air. The chemical modifications resulting from photooxidation were followed by IR and UV-visible spectroscopies. The infrared analyses of PLA photooxidation show the formation of a band at 1845 cm(-1) due to the formation of anhydrides. A photooxidation mechanism based on hydroperoxide decomposition is proposed. The mechanism proposed is confirmed by an increase in anhydride formation rate: the main responsible for this acceleration was identified as transition metals contained in the nanofillers as impurities and involved in the catalytic hydroperoxide decomposition.