Effects of added nanoclay for styrene-acrylic resin on intumescent fire retardancy and CO/CO2 emission

Coating plywood with intumescent paint is an effective approach to ensure fire safety in materials. This study investigated the effects of applying an intumescent coating with nanoclay and different amounts of Cloisite 15A (1%, 3%, 5%, and 10%) on 4-mm plywood panels. The nanoclay coating had a lower total heat release and peak heat release rate than other approaches, and it significantly enhanced the fire retardancy of painted plywood. In addition, nanoclay treated with an organic modifier has better flame retardancy than unmodified nanoclay. Another critical parameter in this study was the concentration of organoclay added to the intumescent coating. Cloisite 15A at a concentration of 1% further enhanced the fire retardancy of plywood. A higher organoclay concentration can reduce CO emissions; however, it also increases CO2 emissions during combustion. The intumescent char layers containing 1% and 3% organoclay had the most extensive phosphocarbonaceous structures according to Fourier-transform IR spectroscopy and 27Al and 31P nuclear magnetic resonance analyses. Regarding the mechanism of fire performance and CO/CO2 emissions, the addition of 1% and 3% Cloisite 15A to intumescent coatings is recommended; it achieved superior performance to Cloisite 15A at a higher concentration (i.e., 10%).