Hydrotalcite and nanometric silica as finishing additives to enhance the thermal stability and flame retardancy of cotton

Suspensions of nanoparticles (namely, hydrotalcite and nanometric silica) have been employed during the finishing of cotton in order to improve its thermal stability and/or flame retardancy. The immersion approach has also been coupled to a surface pre-treatment of the textile by cold oxygen plasma in order to load a higher amount of nanoparticles onto fibres. The time of immersion and the resulting distribution of the nanoparticles onto the fibres, evaluated by scanning electron microscopy in combination with elemental analysis, have been thoroughly investigated. The present study has shown that the above parameters are functions of nanoparticle type. Pre-treatment by cold plasma has been found to be more effective than the immersion only. As far as the thermal stability and the combustion behaviour of treated cotton are concerned, the nanoparticles turned out to be able to delay the degradation in air, modifying mechanism and kinetics, and at the same time enhancing the flame retardancy of cotton by increasing the time to ignition and decreasing the heat release rate peak during the combustion. The joint effect of the two nanoparticles has also been evaluated and found more efficient than the effect of single species.