Investigation On Flame Retardancy Of Polyaniline-And Polypyrrole-Coated Conductive Paper Prepared Via In Situ Synthesis

Polyaniline (PANI)-and polypyrrole (PPy)-coated conductive paper composites were prepared via in situ chemical polymerization process, and their flame-retardant properties were investigated in this paper. The effects of doping acid and oxidant species and the doping conditions were discussed. Some instrumental analysis methods such as SEM, XPS, and TGA were used to clarify the mechanism of the flame-retardant properties of the conductive papers.Both the conductivity and the flame retardancy of polyaniline-coated paper increased with increasing the amount of PANI deposited on the cellulose fibers. Four kinds of inorganic acids (i.e., sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid) were used as doping acid to prepare the PANI-coated paper. For the conductivity, the four doping acids were listed in order from the best to the worst as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid. For flame retardancy, phosphoric acid performed best among all the used inorganic acids, and the other three acids were listed in order from the best to the worst as sulfuric acid, nitric acid, hydrochloric acid. The optimum concentration of four inorganic acids was1mol/L, and the oxygen index (OI) value of conductive paper was28.31%when doped with phosphoric acid at this concentration. P-toluenesulfonic acid (PTSA) and sulfosalicylic acid (SSA) were adopted as doping acid to prepare the PANI-coated paper, both the conductivity and the OI value increased with the increase of acid concentration. SSA performed better than PTSA for both the conductivity and the OI value of conductive paper.Phosphoric acid together with other inorganic acid was used as codoping acid to prepare PANI-coated paper, and the best result could be obtained when the molar fraction of H3PO4was50%. Both the conductivity and the OI value of (H3PO4+SSA) doped conductive paper increased with the increase of molar fraction of SSA. The conductivity of paper increased from1.055S/m to3.985S/m when the molar fraction of SSA increased from0to10%.Both the conductivity and the flame retardancy of polypyrrole-coated paper increased with the increase of the amount of PPy deposited on the cellulose fibers. Three kinds of oxidants (ferric chloride, ferric sulfate, ammonium persulfate) were used to prepare conductive paper, it was found that ferric chloride performed best for the conductivity and ammonium persulfate performed best for the flame retardancy of paper among the three oxidants.The properties of PANI-and PPy-coated papers were compared, it was found that PPy-coated paper performed better for the conductivity and PANI-coated paper performed better for the flame retardancy. The environmental stability of conductivity of PANI-coated paper was better than that of PPy-coated paper, and the environmental stability of flame retardancy of PANI-coated paper was worse than that of PPy-coated paper. The results of SEM showed that the residue of the PANI-coated conductive paper after burning kept the fiber morphology, and some micro particles were observed. The results of XPS showed that the carbon content increased after the conductive paper was burned, which verified that PANI and part of cellulose fibers were carbonized. The results of TGA confirmed the effect of doping acid on the flame-retardancy of PANI-coated conductive paper.