Low-density aerogels have shown great potential as excellent oil–water separation materials in dealing with the growing problem of marine pollution, but they typically suffer from low oil adsorption capacity, complex process flow, expensive raw materials, and poor recyclability. In this paper, inexpensive industrial raw material melamine was introduced into the framework of graphene aerogels, which can be formed into gels (NGAs) in just one step. High-temperature carbonized nitrogen-doped graphene aerogels (N 0.5 CGAs-2) have the advantages of ultralow density, high porosity, repeatable compressibility, hydrophobicity, and excellent adsorption capacity. In addition, depending on the characteristics of the contaminants, N 0.5 CGAs-2 can be selected for different recycling methods and exhibits excellent reusability in cycling. It has a high application value for solving water pollution problems caused by oil spill accidents and chemical spills.
The polymethacrylimide/silicate (PMI/silicate) composites were successfully prepared from the monomers of acrylonitrile (AN) and methacrylic acid (MAA) via the monomer in situ intercalation polymerization and free foaming. The formation of imide groups was monitored by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results of FTIR and XPS indicated that the imide groups were gradually formed and cyano groups were dwindling but still existed during foaming and thermal treatment. The thermogravimetric analysis results revealed that the thermal stability of the PMI/silicate composites was improved, the rate of thermal degradation was reduced, and the residue was increased because of the addition of silicates. The results of dynamic mechanical analysis revealed that the rigidity and the glass transition temperature of the composites were improved. The limit oxygen index (LOI) and cone calorimeter (CONE) test showed that the fire-retardant properties were improved because of the barrier effect of silicates. The cell morphologies of the PMI/silicate composites were characterized by scanning electron microscopy (SEM), and the results showed that the silicate particles were distributed on the cell walls, but the cells slightly cracked. The mechanical properties were measured by tensile, flexural, and compressive strength. The mechanical strength, especially flexural strength, was significantly improved. The flexural strength of PMI/MMT, PMI/kaolin, and PMI/talc containing 8 wt% silicates was improved to 172%, 240%, and 233%.
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