Layer-by-layer-assembled chitosan/phosphorylated cellulose nanofibrils as a bio-based and flame protecting nano-exoskeleton on PU foams. (15th December 2018)

• Record Type: Journal Article
• Authors: Carosio, F.; Ghanadpour, M.; Alongi, J.; Wågberg, L.
• Is Part Of: Carbohydrate polymers. Volume 202(2019)
• Page Start: 479
• Page End: 487
• Publication Date: 2018-12-15
• Subjects: Layer-by-layer -- Chitosan -- Phosphorylated cellulose nanofibril -- Polyurethane foams -- Thermal stability -- Flame retardancy; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2018.09.005
• Languages: English
• ISSNs: 0144-8617

Abstract

Graphical abstract: Highlights: Chitosan and phosphorylated cellulose nanofibrils are layer-by-layer assembled. The assembly produces an exoskeleton on the complex structure of flexible foams. Intermolecular ionic interactions result in impressive mechanical properties. The coating prevents foam collapsing and reduces heat release rates. Unique compositional and structural features result in synergistic interactions. Abstract: The layer-by-layer (LbL) assembly of chitosan (CH) and phosphorylated cellulose nanofibrils (P-CNF) is presented as a novel, sustainable and efficient fire protection system for polyurethane foams. The assembly yields a linearly growing coating where P-CNF is the main component and is embedded in a continuous CH matrix. This CH/P-CNF system homogenously coats the complex 3D structure of the foam producing a nano-exoskeleton that displays excellent mechanical properties increasing the modulus of the foam while maintaining its ability of being cyclically deformed. During combustion the CH/P-CNF exoskeleton efficiently prevents foam collapse and suppresses melt dripping while reducing the heat release rate peak by 31% with only 8% of added weight. The coating behavior during combustion is investigated and correlated to the observed performances. Physical and chemical mechanisms are identified and related to the unique composition and structure of the coating imparted by the LbL assembly.