Multifunction of epoxy resin with biomass carbon dot as synergetic flame retardant for outstanding smoke suppression and toxic attenuation

With the rapid progress of electronics and 5 G technology, high flame retardancy and low toxicity epoxy resin have been crucial. Hence, the bio-carbon dot (CD) doped with N, P, and Mo elements was prepared by hydrothermal method using corn straw as the biomass carbon source, ethylenediamine as the nitrogen source, and phosphomolybdic acid as the phosphorus and molybdenum source. As a P-containing compound, ADP complexed with CD containing the transition metal element Mo on the surface to obtain complexes (ADP/CD). The flame retardant epoxy resin composites (EP/ADP/CD) were further prepared by ADP/CD as a flame retardant and 4,4 '-diaminodiphenylmethane (DDM) as a curing substance. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the shape and chemical structure of CD. The experimental results indicate that when the additive amount of ADP/CD was 4 % (ADP: CD=3.5:0.5), the limiting oxygen index (LOI) of the EP/3.5ADP/0.5CD was 37.5 % (41.5 % higher than pure EP) and reached the UL94 V-0 rate. Cone calorimeter testing revealed a 51.4 %, 39.1 %, 19.6 %, and 70.4 % decrease in the peak heat release rate (pHRR), total heat release (THR), carbon monoxide production (COP), and carbon dioxide production (CO2P) of EP/ADP/CD. respectively, then with EP. Furthermore, the mechanical properties of EP/ 3.5ADP/0.5CD were discussed. Therefore, this work designs a flame-retardant carbon dot, providing a new scheme for creating a multifunctional epoxy resin with flame retardancy, smoke reduction, and toxicity reduction.