Zinc oxide coated cellulose nanocrystals, sourced from wood, were tested in 4mm HDPE sheets. Zinc oxide is widely used in for example sunscreens. The zinc oxide (50%) – cellulose (50%) nano-particles were ground to a particle size < 44 µm, then screw extruded into HDPE (high density polyethylene). At 0.6% loading, peak heat re-lease rate was reduced by 17%, total smoke release was reduced by 6% and mechanical properties (elasticity, strength) were marginally improved (compared to neat HDPE). However, at 1% loading fire and mechanical performance were not as good as at 0.6%: the authors suggest that this is because of uneven dispersion during processing. The Montana State University has been granted a NIST grant of US$ 220 000 for further work.
“MSU researcher advancing ways to make fire-resistant plastics using wood product”, 4th March 2020 https://www.montana.edu/news/19676/msu-researcher-advancing-ways-to-make-fire-resistant-plastics-using-wood-product
“Functionalized Cellulose Nanocrystals: A Potential Fire Retardant for Pol-ymer Composites”, Polymers 2019, 11, 1361, https://doi.org/10.3390/polym11081361