Abstract: Using microscale thermogravimeter TG and micro calorimeter MCC, the pyrolysis and combustion characteristics of aramid 1414, flame retardant viscose fiber and the mixed materials were analyzed. The synergistic effect of co pyrolysis and combustion process was investigated. Results showed that, the co pyrolysis was mainly divided into the first stage of pyrolysis of flame retardant viscose fiber and second stage of pyrolysis of aramid 1414. With the increase of flame retardant viscose content, the mixing moved the first stage of initial thermal decomposition temperature forward, and the second stage of initial thermal decomposition temperature backward. The difference between HRR experimental data and calculation result of MCC showed that the 3 kinds of mixed fiber materials of aramid/viscose being 50/50, 35/65, 25/75 have negative synergistic effect of pyrolysis at the pHRR1 peak region, and all of the 5 kinds of mixed materials have positive synergistic effect of pyrolysis, with the synergistic effect of pyrolysis of aramid/viscose 35/65 being the weakest. Root mean square and oxygen index proved that of all the mixed materials, aramid/viscose 35/65 has weak synergistic effect of pyrolysis, and is more suitable for blended fabric of flame retardant protective clothing from the perspective of flame retardant.

Key words: pyrolysis, combustion, heat release, flame retardant fiber, synergistic effect