Eco-friendly flame-retardant based on sap from banana plant pseudostems

Society's need for safe flame-retardant technologies in passive fire protection is undeniable. To address this concern, this paper presents an experimental investigation of the fire-retardant properties of slash pine wood treated with banana plant pseudostem sap, obtained from a cultivated banana plant variety widely grown in Brazil. The natural sap extract was characterized through X-Ray Fluorescence spectrometry and Fourier Transform Infrared Spectroscopy techniques, revealing the presence of key components, including water, potassium chloride, sodium chloride, sodium silicate, calcium phosphate, sodium phosphate, lignin and tannins. The authors explored different treatment parameters, including various sap impregnation times, number of impregnations and use of natural versus various levels of concentrated sap. First, a horizontal burning test, similar test to UL 94 HB, was used to obtain an initial assessment of the suitability of sap as a flame retardant for slash pine wood. Subsequently, the Mass Loss Calorimeter equipment with thermopile attachment described in ISO 13927:2015 was used to measure various heat release rate parameters. The findings suggest that reducing the water content in sap and increasing the number of repeat treatments results in a more effective treatment for slash pine wood. More specifically, the results indicate that the most efficient treatment involves three impregnations with high-concentration (1/10 volume reduction) sap. Future work to improve the efficacy of the concentrated sap impregnation process could explore the use of pressure treatment instead of soaking.