Keywords: thermal-degradation, agent, intercalation, retardation
Abstract: The effects of Ni2+-Fe3+ layered double hydroxide (LDH) as a synergistic agent on the flame retardancy of intumescent flame retardant (IFR) polypropylene composites were studied; the IFR system mainly consisted of melamine phosphate (MP) and pentaerythritol phosphate (PEPA). The flame retardancy was studied by the limiting oxygen index (LOI), UL-94 test, cone calorimetry (CONE) and microscale combustion calorimetry (MCC). Thermal decomposition analysis was investigated via thermogravimetric analysis (TGA), real time Fourier transform infrared spectroscopy (RTFTIR) and thermogravimetric analysis/infrared spectroscopy (TG-IR). The crystallization behavior was tested by the differential scanning calorimetry (DSC). Char residues were analyzed by scanning electron microscopy (SEM) and Raman diffusion spectroscopy. Results demonstrated that a little addition (0.2%) of Ni2+-Fe3+ LDH could improve the flame retardancy of PP/MP/PEPA composites, and affect the P-O-C degradation of MP/PEPA in PP. The crystallinity of the composites is lowered by Ni2+-Fe3+ LDH. It also has an influence on the structure of char residual, which may benefit the flame retardancy and thermal stability of materials.