Phytic acid (inositol hexakisphosphate acid), a phosphorus-rich, bio-degradable, natural chemical, is widely present in plant materials such as grains, beans and oil seeds. It is not a useful food component because it cannot be digested by humans, poultry or pigs. Because of its high phosphorus content, phytic acid has PIN flame retardant properties.
Here it was tested for treatment of the bio-sourced polymer poly lactic acid (PLA), as a nonwoven fabric 80 g/m2. The PLA fabric was soaked in 70% solution of phytic acid in water, and then dried. This resulted in formation of a char layer on the PLA fabric during fire tests with an increase in LOI (loss on ignition) of the PLA fabric from 26% to 36%. The PHRR (peak heat release rate) was nearly halved and the area of damage was reduced in a vertical burning test. The authors underline however that because phytic acid is water soluble, this treatment is not durable.
X-W. Cheng et al. “Phytic acid as a bio-based phosphorus flame retardant for poly(lactic acid) nonwoven fabric”, J. Cleaner Production, 2016 https://dx.doi.org/10.1016/j.jclepro.2016.02.113