Abstract
In this study, paraffin was selected as the phase change material (PCM) and high-density polyethylene (HDPE) as the supporting material to prepare a flame-retardant PCM system. The system consisted of paraffin, HDPE, expanded graphite (EG), magnesium hydroxide (MH) and aluminum hydroxide (ATH). The thermal stability and flame retardancy were studied by thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) and cone calorimeter test (CONE). The SEM proved that the addition of MH and ATH can produce an oxide film on the surface of the composite material and form a “physical barrier” with the char layer, generated by the expansion of EG, preventing the transfer of heat and oxygen. The TGA test showed that, compared with other flame-retardant systems, the materials with added MH and ATH have a higher thermal stability and carbonization ability, and the amount of char residue has increased from 17.6% to 32.9%, which reduces the fire risk of the material. The flame retardant effect is obvious. In addition, the addition of MH and ATH has no significant effect on the phase transition temperature and latent heat value of PCMs. The CONE data further confirmed that MH and ATH can work with EG to prevent heat release, reduce the total heat release rate (THR) value and effectively suppress the generation of smoke, CO and CO2. The peak heat release rate (PHRR) value also decreased, from 1570.2 kW/m2 to 655.9 kW/m2.
Highlights
Phase change materials (PCMs) are substances that change the physical phase state and can absorb and release energy with the change of external temperature
The peak shoulder relates to a solid–solid transition, and the main peak is associated with the melting of the crystallites [25], as shown by the DSC curve of pure paraffin in. This illustrates that the addition of magnesium hydroxide (MH) and ATH has no significant effect on the phase transition temperature of PCMs
The results show that the thermal stability and flammability properties of the paraffin/high-density polyethylene (HDPE)/expanded graphite (EG)/MH/ATH system are significantly improved
Summary
Phase change materials (PCMs) are substances that change the physical phase state and can absorb and release energy with the change of external temperature. PCMs are widely used in building, industry, construction and solar heating fields based on their new energy-saving, environmental-friendly properties. In recent years, researchers have applied PCMs to the field of building thermal energy storage [1,2,3]. As one of the typical PCMs, has been widely used for building thermal energy storage, due to its large latent heat, chemical stability, low cost and wide range of commercial availability [4,5,6]. Paraffin is easy to leak when phase change occurs, which brings inconvenience to practical applications, and so research into form-stable PCMs has emerged. The form-stable PCM is composed of a PCM and other supporting material. When the phase change occurs, the supporting material with a higher melting point will keep the materials in their
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