Investigation of nickel ammonia phosphate with different morphologies as a new high-efficiency flame retardant for epoxy resin. (May 2020) - Zhang, Weiwei
Nanowires, nanosheets, and microflowers of nickel ammonium phosphate (NiNH4 PO4 ·H2 O) were synthesized by a mixed solvothermal method and used to improve the flame retardancy of epoxy resin (EP). The solvent concentration and surfactant content were found to play a key role in nucleation and growth of NiNH4 PO4 ·H2 O. The structure of NiNH4 PO4 ·H2 O was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The flame retardancy, thermostability, mechanical properties, and flame retardancy mechanism of EP/NiNH4 PO4 ·H2 O composites were analyzed using the limiting oxygen index (LOI), cone calorimetry (Cone), mechanical property tests, thermogravimetric analysis, and thermogravimetric–Fourier transform infrared spectroscopy. The results indicated that NiNH4 PO4 ·H2 O has proper thermal stability and greatly improves the flame retardancy of EP. The nanosheets outperformed the other morphologies; the EP/5% NiNH4 PO4 ·H2 O nanosheets have an LOI of 35.2%, which exceeds that of pure EP (24.7%). Furthermore, Cone showed that these nanosheets have the lowest peak heat release rate and peak smoke production rate, which are 69.1% and 36.5% lower than those of pure EP, respectively. NiNH4 PO4 ·H2 O can promote the formation of a stable char layer and release nonflammable gases, thus protecting the matrix by preventing heat and oxygen transfer and reducing the concentration of combustible gas. NiNH4 PO4 ·H2 O is expected to serve as a new high-efficiency flame retardant for EP.