Fire Properties of Paper Sheets Made of Cellulose Fibers Treated with Various Retardants

This article presents the results of flame-retardancy tests conducted on cellulose sheets produced using a Rapid Köthen apparatus treated with retardants. The agents used were potassium carbonate (PC) K₂CO₃ (concentrations of 20; 33.3; and 50% wt/wt), monoammonium phosphate (MAP) NH₄H₂PO₄ (concentrations of 35% wt/wt), diammonium phosphate (DAP) (NH₄)₂HPO₄ (concentrations of 42.9% wt/wt), and bisguanidal phosphate (FOS) C₂H₁₀N₆ (concentrations of 22.5% wt/wt). The agents were used to improve Kraft cellulose-based sheets' flame-retardant properties and compare their performances. As part of the study, the flammability of the materials was determined by the following methods: an oxygen index (OI) test, a mass loss calorimeter (MLC) test, and a mini fire tube (MFT) test. All formulations showed an increase in flame retardancy compared to the control test. All protected samples were non-flammable for OI determinations, and DAP-protected samples showed the highest OI index. For the MLC test, DAP-protected and MAP-protected samples showed the best heat-release rate (HRR), total heat release (THR), and average heat-release rate (ARHE) (samples did not ignite for 600 s). In the MFT test, all treated samples had comparably reduced weight loss. The best parameter was achieved for MAP and DAP (15% weight loss).