A new flame retardance strategy for shape stabilized phase change materials by surface coating

•A new flame retardant strategy for SSPCMs by surface coating was proposed.•The LOI values increased from 18.7 vol% to 35.9 vol% and 36.9 vol%.•UL-94 V0 ranking was achieved at the vertical burning test.•The PHRR decreased by 60% and the burning processes prolonged significantly.•EG and RP in the coating contributed to the improved flame retardance.

A new flame retardance strategy for shape stabilized phase change materials (SSPCMs) by surface coating was proposed. The coating was composed of acrylic resin, expandable graphite (EG) and/or red phosphorous (RP). The flame retardant effects of surface coatings on SSPCMs were evaluated by limiting oxygen index (LOI) determination, vertical burning test, cone calorimeter test, field emission scanning electron microscopy (FESEM) and thermogravimetric analysis-Fourier transfer infrared spectrometry (TGA-FTIR). The results showed that surface coated SSPCMs exhibited very good flame retardance, with the LOI values increasing to 35.9 vol% and 36.9 vol%, respectively, from 18.7 vol%. And UL-94 V0 level was achieved at the vertical burning test. In contrast, the same loading of EG and/or RP contributed little to flame retardance of SSPCMs when they were melt-blended into the bulk. The cone calorimeter test revealed that peak heat release rates (PHRR) of surface coated SSPCMs decreased by 60%, and the burning processes prolonged significantly. The flame retardant mechanism of surface coating was investigated using TGA-FTIR. The results showed that EG played a crucial role. When samples were exposed to flame, EG expanded and absorbed evaporated paraffin and heat at the same time so that the combustibles and temperature were decreased. Keywords: Shape stabilized phase change material (SSPCM), Flame retardant property, Surface coating, Expandable graphite (EG), Red phosphorus (RP)

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