Guanidine Hydrogen Phosphate-Based Flame-Retardant Formulations for Cotton

Classical flame-retardant treatments for cellulosic materials are phosphorous-nitrogen-based compounds. In this work, cotton fabric is treated with different formulations based on diguanidine hydrogen phosphate (DGHP) or monoguanidine dihydrogen phosphate (MGHP), individually or in combination with a resin (melamine) or with 3-amino propylethoxysilane (APS). Flame behaviour of the treated cotton fabrics is evaluated using the electric burner test and the limiting oxygen index (LOI). Their thermal stability is then examined using thermal analysis. While all the formulations raise LOI higher than 30 vol.%, it was noticed that MGHP provides better flame-retardant properties than DGHP. The formulations can be classified into two groups: the first group, raising the LOI value between 30 and 40 vol.%, corresponds to the formulations of guanidine with or without melamine, and the second group, providing an LOI value between 60 and 70 vol.%, is formulations with APS. TG analysis reveals a significant difference in the thermal degradation of these two groups. While this degradation is initiated at lower temperatures for all padded fabrics compared to untreated cotton, the residual amounts of char is higher at 800 C for formulations with APS (i.e. the second group).