Improving the flame retardancy of PET fiber by constructing the carbon microspheres based melamine polyphosphate powder

Carbon microspheres (CMSs) as carbon source, melamine phosphate (MP) as acid source and gas source, the integrated CMSs based MP composites (SiMP-CMSs) was in-situ prepared to improve the flame retardancy of PET fiber. A series of SiMP-CMSs/PET fiber were prepared by the melt spinning method. By investigating the thermal stability, flame retardancy, flame-retardant mode, crystallization and orientation degree of PET composite fiber, the results showed that, with the addition of 0.9 wt% SiMP-CMSs, the LOI value and vertical combustion grade of SiMP-CMSs/PET composite fiber was 27.4% and B1 level. The main flame-retardant mode of SiMP-CMSs/PET fiber was 31.33% physical barrier, 36.04% flame inhibition and 11.12% catalytic charring. The thermal decomposition temperature was delayed, and the residual amount increased from 11.34% to 16.13%. With the accelerated crystallization rate and the increased grain orientation, the aggregated structure of SiMP-CMSs/PET fiber was also optimized.