Preparation of linear piperazine/phosphorous/polysiloxane copolymer and its application on cotton fabrics

A novel flame retardant α, ω-di[(4-butoxy-piperazin-1-yl)-phosphinic acid methyl ether]-terminated linear polysiloxane was prepared. The flammability and thermal decomposition behaviors of fabrics were systematically estimated by limiting oxygen index, vertical burning test, horizontal flame test, thermogravimetric analysis and cone calorimeter, respectively. The combustion performances of fabrics have proven to be intensely affected by flame retardant. As a result, the value of limiting oxygen index enhanced from 18 to 30%, and the ignition time increased too. The values of total heat release, heat release rate and mass loss decreased. This also can be confirmed by the increase in ignition time/the relative peak ratio and the decrease in CO2/CO ratio. The morphologies of the residues were investigated by scanning electron microscopy, and it showed that flame retardant formed an expandable char layer to play a protective role in the degradation of fabrics. The chemical structure of residue of fabric was studied by Fourier transform infrared, and the result demonstrated that the treated fabric showed better flam retardant property by promoting the carbonization of fabric, forming the carbonaceous–siliceous layer. In addition, through the wash durability test, the value of limiting oxygen index of the treated fabric remained at 26.3% after 25 times washing, while the one of the untreated fabrics was 18.0%, which meant a better durability flame-retarding effect of the treated one. The tearing strength, tensile strength and wrinkle recovery angle were also investigated to analyze the effects of the flame retardant on untreated fabric.