Humic acid (HA), a biomass material with plentiful oxygen‐containing functional groups, showed huge potential to be considered as a promising charring agent in flame retardancy. In this study, this HA was modified with four different metal ions like Fe2+, Mn2+, Al3+, and Cu2+ and finally, introduced into the epoxy resin (EP) to enhance the flame retardancy of the EP and the dispersion of these flame retardants into the EP matrix. When 10 wt% of HA‐Fe and HA‐Mn were incorporated into EP matrix, the limiting oxygen index (LOI) was increased from 21.2% for EP to 26.6 and 25.3% for the EP composites and the peak heat release rate (pHRR) was reduced by 36 and 35.5%, respectively. Such a significant improvement in flame retardancy was attributed to the catalytic charring of HA in the presence of metal ions, which ultimately increased the residual char formation and produced compact char layers during the combustion process to retard the transfer of heat and combustible gases between the EP composites and the flame zone. Finally, this kind of application provided a feasible way for the development of an environmentally friendly flame retardant with high efficiency, which improved the fire safety of EP matrix.
In
this work, self-lubricating boron nitride nanosheets (BNNs)
were decorated with flame-retardant zinc ferrite (ZnFe2O4), followed by stearic acid modification to obtain magnetic
and hydrophobic properties. Under the external magnetic field, the
obtained ZnFe2O4–BNNs can be well ordered
into one-dimensional orientation in the epoxy resin (EP) matrixenabling
improved flame retardant properties. Compared to a randomly oriented
ZnFe2O4–BNN equivalent, the well-orientated
ZnFe2O4–BNNs (at 10% mass fraction) reduce
the peak heat release rate and CO production by 47 and 51%, respectively.
Furthermore, the ZnFe2O4–BNN/EP composite
monoliths demonstrate excellent durability, displaying continued superhydrophobicity
under Taber abrasion, high external pressure, knife scratch, long-term
exposure to acids/bases, and harsh UV irradiation. In addition, the
result shows that the well-oriented ZnFe2O4–BNN/EP
composite demonstrates better tribological performance and the friction
coefficient is reduced by 76.9%.
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