Significantly improved flame-retardancy of cellulose acetate nanofiber by Mg-based nano flaky petal

Flower-shaped hydromagnesite (MgO-P) and magnesium oxide (MgO) micro spheres were synthesized via precipitation-aging method with and without calcination. The disassociated nano flaky petal of around 50 nm (~ 20 nm in thickness) of MgO-P and MgO by sonication were used as flame-retardants for the electrospun cellulose acetate (CA)/MgO-P or CA/MgO nanofiber. SEM, XRD, FTIR, HRTEM were used to characterize all related products. TGA was used to analyze the detailed decomposition procedures of bare, MgO-P, and MgO doped CA nanofiber. Three evaluation methods including broken time after heating, thermography during heating, and combustion observation were adopted to compare the flame-retardancy of composited nanofibers. Doped CA nanofibers showed best flame-retardancy by extending the heat-induced broken time from 0.46 to 12.09 s, which is 26.3 times that of CA nanofiber. The flame of CA/MgO-P and CA/MgO could be self-extinguished once the ignition source was removed. No smoke and size shrinkage could be observed during the combustion of CA/MgO-P or CA/MgO nanofibers. Corresponding flame-retarding mechanism of Mg-based nano flaky petal was proposed.