Improved Fire Retardancy of Cellulose Fibres via Deposition of Nitrogen-Modified Biopolyphenols

• Published in: Molecules (Basel, Switzerland) Vol. 27; no. 12; p. 3741
• Main Authors: Pöhler, Tiina, Widsten, Petri, Hakkarainen, Tuula
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 10.06.2022; MDPI
• Subjects: Adsorption; Calorimetry; Carbon footprint; Cellulose; Cellulose fibers; Cellulose pulp; Construction industry; Decomposition; Fibers; fire performance; fire retardant; Flame retardants; Heat; Heat release rate; Heat transfer; Insulation; Lignin; micro-scale combustion calorimetry; modification; Nitrogen; Parameter modification; Polyphenols; Tannins
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules27123741

Driven by concerns over the health and environmental impacts of currently used fire retardants (FRs), recent years have seen strong demand for alternative safer and sustainable bio-based FRs. In this paper, we evaluated the potential of nitrogen-modified biopolyphenols as FRs for cellulosic natural fibres that could be used in low-density cellulose insulations. We describe the preparation and characterisation of nitrogen-modified lignin and tannin containing over 10% nitrogen as well as the treatment of cellulose pulp fibres with combinations of lignin or tannin and adsorption-enhancing retention aids. Combining lignin or tannin with a mixture of commercial bio-based flocculant (cationised tannin) and anionic retention chemical allowed for a nearly fourfold increase in lignin adsorption onto cellulosic pulp. The nitrogen-modified biopolyphenols showed significant improvement in heat release parameters in micro-scale combustion calorimetry (MCC) testing compared with their unmodified counterparts. Moreover, the adsorption of nitrogen-modified lignin or tannin onto cellulose fibres decreased the maximum heat release rate and total heat release compared with cellulose reference by 15–23%. A further positive finding was that the temperature at the peak heat release rate did not change. These results show the potential of nitrogen-modified biopolyphenols to improve fire-retarding properties of cellulosic products.