Magnesium hydroxide and microencapsulated red phosphorus synergistic flame retardant form stable phase change materials based on HDPE/EVA/OMT nanocomposites/paraffin compounds

The flame retardant form stable phase change materials (PCM) based on high density polyethylene (HDPE)/ethylene-vinyl acetate (EVA)/organophilic montmorillonite (OMT) nanocomposites and paraffin compounds were prepared. The flame retardant system used consisted of magnesium hydroxide (MH) and microencapsulated red phosphorus (MRP). The structures and properties of the form stable PCM composites were respectively characterised by X-ray diffraction (XRD), scanning electronic microscope (SEM), thermogravimetry analysis (TGA), differential scanning calorimeter (DSC) and cone calorimeter. The XRD and SEM results showed the paraffin dispersed in the three-dimensional net structure formed by HDPE-EVA/OMT nanocomposites. The TGA results indicated that the loading of the MH/MRP and OMT improved the thermal stability and thermal oxidative degradation properties of the form stable PCM composites. The DSC measurements indicated that the additives of flame retardant and OMT had little effect on the thermal energy storage properties. It was also found from the cone calorimeter tests that the peak of heat release rate (PHRR) decreased significantly. Both the decrease in the PHRR and compact and homogeneous charred residue after combustion indicated that there was a synergistic effect among the MH, MRP and OMT, contributing to the improved thermal and flammability properties of the form stable PCM composites.