Preparation of halogen-free flame retardant hybrid paraffin composites as thermal energy storage materials by in-situ sol–gel process

Novel halogen-free flame retardant hybrid phase change composites were prepared by an in-situ sol–gel process, using paraffin as the thermal energy storage material and tri-(triethoxysilylpropyl) phosphamide as the sol–gel precursor. The structure of paraffin composites was characterized by Fourier transform infrared spectrum (FT-IR) and X-ray diffraction (XRD). The behaviors of thermal stability and thermal energy storage properties were investigated through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The char residue of composites was characterized by FT-IR, XRD and scanning electron microscope (SEM). The flame retardancy property of paraffin composites was investigated by pyrolysis combustion flow calorimetry (PCFC). Results showed that the paraffin composites had good thermal energy storage property as well as enhanced thermal stability and flame retardancy properties.

► Halogen-free flame retardant paraffin composites were prepared by the sol–gel process.
► Paraffin composites had large latent heat value and significantly reduced PHRR.
► Hybrid silsesquioxane increased the thermal stability of paraffin composites.
► Paraffin composites had potential to be used as thermal energy storage materials.