Effect of Microencapsulated Long-Chain Chlorinated Paraffin on Flame Retardant of Rigid Polyurethane Foam

To overcome the fire risk of rigid polyurethane foam (RPUF) and the poor thermal stability of long-chain chlorinated paraffin (LCCP), the microcapsules of long-chain chlorinated paraffin (MCP) were prepared by in-situ polymerization with melamine formaldehyde resin (MF) as shell material, and the flame retardant rigid polyurethane foam (MCP/ RPUF) was obtained through introducing MCP as the flame retardant. Meanwhile, the core-shell composition, surface morphology, chemical composition, particle size distribution, and thermal stability of flame retardant microcapsules were evaluated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TG). The characterization data indicated that the flame retardant microcapsules were successfully synthesized and had excellent particle size distribution. In addition, microcalorimeter (MCC), limiting oxygen index (LOI), UL-94 vertical burning tests, scanning electron microscope (SEM), Raman spectroscopy, and other methods were used to analyse the flame retardancy and carbon residue of rigid polyurethane foam. The results show that the 20% MCP/RPUF composite can pass the V-0 grade of UL-94 and reach the material flame retardant grade. Compared with pure RPUF, the peak heat release rate and total heat release of the MCP/RPUF composite are greatly reduced. Therefore, the addition of flame retardant microcapsule improves the graphitization degree and compactness of rigid polyurethane foam carbon slag, increasing the fire safety of the composite.