Coffee wastes showed some fire performance effect in epoxy, and better effect if loaded with phosphorus. Coffee wastes are proposed as the base for renewable PIN flame retardants as they contain in particular lignin, cellulose and hemicellulose. Used ground coffee, from a coffee machine, was mixed with dimethyl phosphite then dried to give a material with 20% P loading. 30% loading of dried coffee wastes into epoxy resulted in only a 20% reduction in peak heat release rate, whereas 30% loading of the phosphorus-coffee-waste led to a nearly 40% reduction and to significant char formation. Further work is needed to assess whether the coffee waste brings significant flame retardancy (beyond simply “diluting” the epoxy) or whether the flame retardancy is due only to the phosphorus, and to assess impacts on the mechanical and other properties of the epoxy.
“Coffee Wastes as Sustainable Flame Retardants for Polymer Materials”, H. Vahabi et al., Coatings 2021, 11, 1021. https://doi.org/10.3390/coatings11091021