Intumescent flame retardant and anti-dripping of PET fabrics through layer-by-layer assembly of chitosan and ammonium polyphosphate

High flammability and dripping restrict the widely applications of PET fiber, a lot of efforts have been made to overcome these problems. In this paper, chitosan (CH) and ammonium polyphosphate (APP) were used as the intumescent flame retardant system which was constructed on PET fabrics surface via the Layer-by-layer (LBL) assembly technique. The flame retardancy and anti-dripping performance of the coated PET fabrics were determined by LOI values and vertical burning test. The results revealed that both the flame retardancy and anti-dripping performance of the LBL assembly coated PET fabrics were improved, particularly when the CH/APP bilayer was over 10 BL, the dripping phenomenon was eliminated. Alkali treatment of PET fabrics before LBL assembly effect on the flame retardancy and anti-dripping performance was investigated. The results indicated that alkali treatment of the PET fabrics would promote the combination of PET fabrics and the charged flame retardants. Thermogravimetric analysis (TGA) was used to investigate the thermal stability of uncoated and LBL assembly coated PET fabrics. The results of TGA revealed that LBL assembly coated PET fabrics would promote the char formation indicating the obviously condensed phase flame retardant action. The SEM images of the char residues revealed that LBL assembly coated PET fabrics would promote the formation of intumescent char residues with lots of microporous indicating the better anti-dripping performance.