A quantitative evaluation method of the barrier property of the residue for flame retardant polymers

To investigate the flame retardant properties and mechanisms of those fire retardant polymer systems that mainly depend on the produced protective char shields, quantitative analysis for the barrier quality of the char layer is important but still a challenge. In the present article, a novel and simple characterization method based on atmosphere permeability is proposed to quantitatively evaluate the barrier property: an incombustible fabric carrier coated with the flame retardant polymer solution, is carbonized at high temperature to make the produced char residue adhered to the fabric. As the interfibrous gaps are filled and closed by the chars, the atmosphere permeability of the heated fabric decreases compared with that of original one. Their difference value can really reflect the contribution of the charring residue to the barrier property. This method combined with other characterizations including residue morphology observation, vertical burning test, limiting oxygen index, and calorimetric analysis, is very helpful to reveal the correlation between the flame retardance and barrier property of the char residue, evaluate the flame retardant efficiency in the condense phase, and estimate the corresponding flame retardant mechanisms. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45102.