Synthesis Of The Derivatives Of Polyphosphazenes And Its Application On Flame Retartant

The combustion of traditional halogen flame retardants produce a lot of smoke and poisonous gas. It is usually harmful to the environment and human beings. So it is inevitable to develop non-halogenated flame retardants to meet current environmental requirements. Polyphosphazenes exhibit excellent fire retardancy and will not produce poisonous gas.Hexakis(4-formacylphenoxy)cyclotriphosphazene(HAPCP) was synthesized and characterized by FTIR, EA and NMR. Thermogravimetric analysis showed that HAPCP had good thermal stability.HAPCP/PET composites were prepared by melt blending. Thermogravimetric analysis showed that the addition of HAPCP could promote the char formation of PET both in nitrogen and air atmosphere. The value of LOI can be up to34.1%which was higher than pure PET. The morphology of the charred residual was evaluated by SEM. It showed a continuous outer surface and porous internal structure which was proved to be an ideal structure of flame retardant. The kinetic parameters were calculated by Flynn-Wall-Ozawa model. The results showed that increasing heating rate caused thermal hysteresis increased and the TG curve shifted to the high temperature side, and the thermal decomposition activation energy changed with different reactivity. The thermal decomposition activation energy of HAPCP/PET composites was near to pure PET under nitrogen atmosphere, but it was lower than pure PET under air atmosphere.HAPCP/PU composites were prepared by adding HAPCP into the coating solution. Thermogravimetric analysis showed that the addition of HAPCP could promote the char formation of PU both in nitrogen and air atmosphere. The value of LOI can be up to27.3%Which was higher than pure PU. And the morphology of the charred residual was evaluated by SEM. The kinetic parameters were calculated by Flynn-Wall-Ozawa model. The results showed that increasing heating rate caused thermal hysteresis increased and the TG curve shifted to the high temperature side, and the thermal decomposition activation energy changed with different reactivity. The thermal decomposition activation energy of HAPCP/PU composites was higher than pure PU under nitrogen atmosphere. The thermal decomposition activation energy of5%HAPCP/PU composite was higher than pure PU under air atmosphere while the values of10%HAPCP/PU composite and15%HAPCP/PU composite were lower than pure PU.The results of this study showed that the addition of HAPCP could effectively promote the char formation of PET and PU. So it could improve the thermal stability and flammability of the materials.