Flame Retardant Silk Fabrics Prepared By Electrostatic Layer-by-layer Self-assembly Procedure

In this paper, in order to explore an eco-friendly and energy-saving method forpreparing silk fabrics with good flame retardant property, the silk fabrics were coated withthe phosphorus-nitrogen contained compounds of sodium phytate and chitosan usingelectrostatic layer-by-layer assembly technique. The assembly process parameters,structure, properties and flame retardant mechanism of silk fabrics after assembly werediscussed in this paper.First, from evaluation to limiting oxygen index and one-factor experiments, the optimaltechnological conditions of flame-retardant finishing were found as follows: concentration of CHand SP in the assembly solution both1%(w/w), pH value of the assembly solution5, assemblingwith the positive ions CH first and the assembly time15min, and this completed an alternation ofpositive and negative ions which denoted a layer, assembly time of the second and last layer1minand fabrics assembled with each layer were rinsed three times with distilled water, wrung out to thewater, dried under90℃, the ideal assembly layers20. The limiting oxygen index of flame retardantsilk fabrics assembled under this process conditions was31.9%, being increased by8.8percentagepoints compared with untreated silk fabrics. After being assembled with20or30layers, the silkfabrics can still be subjected to20laundering cycles, which means the fabrics has great washingdurability. The assembled silk fabrics have a little loss of whiteness, tensile strength, handle senseand air permeability. But they didn’t damage the basic fabric performance and other performance.Besides, the molecular weight of chitosan is closely related to the appliedperformance, so it is particularly important to choose an average molecular weight ofchitosan. This method is feasible further after the test of growth rate and determination ofphosphorus content.IR spectra, SEM and XPS measurements of treated silk fabrics showed that the flameretardant was successfully assembled onto silk fabric. Analysis of the XRD showed thatthe assembly reaction was only happened in the amorphous region of silk. Amino analysisresults showed that the amino acid content of silk fabric after flame retardant finishing isnot significantly different from the untreated silk fabrics. The chitosan was chosen as one of the flame retardants because it can get greatsynergistic retardancy effect when used as nitrogen compounds while the sodium phytateas phosphorus component. Besides, great flame retardancy and antibacterial property ofsilk fabrics were obtained after assembling. And it accords with the development directionof high efficiency, environmentally friendly and multi-functional in the textile areas.