Preparation and characterization of double-shell phase change material microcapsules with flame retardancy and temperature regulation capability as low-emission building fillers

Abstract

The building application of phase change materials (PCMs) has attracted widespread attention due to energy conservation and emission reduction. In this study, designed and prepared by two-step polymerization poly melamine tetramethylene phosphonium sulfate (PMTMPS) coating the raw phase change materials microcapsules (MPCMs), which were novel double-shell microcapsules (D-MPCMs). D-MPCMs further achieved low smoke and low toxicity in the fire based on enhancing the temperature regulation performance of MPCMs. The chemical structure of D-MPCMs was characterized by Fourier transform infrared (FTIR) spectroscopy, and 13C solid-state nuclear magnetic resonance (NMR). Transmission electron microscope (TEM) confirmed that D-MPCMs were successfully prepared, whose shapes were regular spherical. The results of differential scanning calorimetry (DSC) showed that D-MPCMs revealed excellent phase transition enthalpy (80.51 J/g). Then, the resultant D-MPCMs had good thermal reliability and stability from the thermogravimetric analysis (TGA), characterized by a residual mass of D-MPCMs was 17 % more than that of MPCMs. In the cone calorimeter test (CCT), we confirmed that the coated PMTMPS significantly reduced the fire risk parameters of the rigid polyurethane foam (RPUF) containing D-MPCMs (D-MPCM/RPUF) referring to the heat release rate (HRR), total heat release (THR), and total smoke production (TSP). D-MPCM/RPUF exhibited the lowest peak values of HRR and TSP, which were 400.115 kW/m2 and 10.512 m2, respectively. In addition, the PMTMPS shell significantly enhanced the solar photo-thermal conversion performance of the D-MPCMs. To sum up, D-MPCMs have great potential to improve flame retardancy, environmental protection, and temperature regulation capability for building thermal insulation materials.