The phosphorus – nitrogen inorganic chemical APP (ammonium polyphosphate) was tested as a PIN flame retardant for jute / polypropylene (PP) 1:1 blend fibre nonwoven felt. APP and PP powder were spread on both sides of the felt then combined into it by hot pressing.
This treatment showed better fire performance (LOI limiting oxygen index, HBR horizontal burning rate) than application of APP by soaking and sodium hydroxide treatment. The optimal fire performance was with 10% APP / zero PP added by surface treatment.
“The flame retardancy and mechanical properties of jute/polypropylene composites enhanced by ammonium polyphosphate/polypropylene powder”, Y. Dou et al., J Applied Polymer Science 2016 http://dx.doi.org/10.1002/app.43889