Hydrogen bond complexasion to prepare guanidine phosphate flame retardant poly(vinyl alcohol) membrane with high transparency

It is a challenge to prepare a flame retardant polymer membrane with high transparency through addition of flame retardants all the time. In the present paper, a compounding method based on hydrogen bonding complexation is used to realize molecule-scale dispersion of a N-P flame retardant (guanidine phosphate (GP)) in poly(vinyl alcohol) (PVA) membrane by the interaction of their intermolecular hydrogen bonds. In this way, a PVA membrane with high transparence can be successfully obtained. Vertical combustion, micro-scale combustion calorimetric, thermo-gravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscope are employed to evaluate the flame retardancy and analyze the corresponding mechanisms. The GP flame retardant PVA membrane with high transparence improves the tensile strength by 47% and achieves UL94 VTM-0 rating when the content of GP is 15 wt%. It shows that the interaction between GP and PVA effectively promote formation of the continuous and stable char in the condensed phase.