Fabrication, characterization and flammability testing of carbon nanofiber layer-by-layer coated polyurethane foam

Abstract

This is the first reported use of Layer-by-Layer (LBL) assembly to fabricate thin film coatings on polyurethane foam, of incorporating carbon nanofibers (CNF) into LBL fabricated coatings, and of using LBL fabricated coatings to reduce the flammability of polyurethane foam. The (359 ± 36) nm thick four bilayer coating of polyethyleneimine/CNF (cationic layer) and poly(acrylic acid) (anionic layer) contained (50.9 ± 0.1) mass fraction % CNF. This CNF coating covered the entire internal and external surfaces of the porous foam. The distribution of the CNFs was nonuniform on the microscale with regions of large CNF aggregation to regions with individual CNFs and isolated regions that appeared to contain no CNFs. Even though the microscopic CNF distribution was non-uniform, the macroscopic CNF network armor that was generated from this LBL process significantly reduced the flammability of the foam; i.e., 55% ± 6% reduction in total heat release and peak heat release rate. This reduction caused by the CNF coating is 50% better than previously reported by incorporating twice as much CNFs directly into the foam and 12% to 47% greater than other technologies currently used to reduce foam flammability.

Flame retardancy testing and regulation of soft furnishings

“…Preliminary efforts in reducing the fl ammability of polyurethane foam by incorporating carbon nanofi bers (CNF) 80 and multi wall carbon nanotubes © Woodhead Publishing Limited, 2013 (MWCNT) 81 into LbL-fabricated thin fi lm coatings have shown promising results. These LbL coatings were found to signifi cantly reduce the fl ammability of PUF, with 55% ± 6% reduction in PHRR and 21% ± 3% reduction in total burn time.…”