Form-stable phase change materials with enhanced thermal stability and fire resistance via the incorporation of phosphorus and silicon

In this paper, a series of novel form-stable phase change materials (PCMs) containing phosphorus and silica were prepared by transesterification of diethyl phosphite with 1-tetradecanol, 1-hexadecanol and 1-octadecanol, followed by ring-opening reaction and hydrolytic condensation of 2,3-epoxypropoxy propyltrimethoxysilane (silane coupler KH-560). The leakage of pure higher alcohols in molten state was effectively solved due to the support of cross-linked silicon network structure. The co-incorporated phosphorus and silicon would accelerate the formation of chars and improve the thermal stability and fire resistance. The chemical structure and crystalline structure of form-stable PCMs were determined by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Differential scanning calorimeter (DSC) results indicate the melting points are in the range of 29 °C to 55 °C with the latent heat between 81.5 J/g to 116.9 J/g. Thermogravimetric (TG) analyses exhibit improved thermal stability of prepared PCMs compared to pure higher alcohols. The results of scanning electronic microscope (SEM), energy dispersive spectroscope (EDS) and FT-IR confirm the formation of phosphorus-rich and silicon-rich compact chars after thermal treatments.