Fabrication of combustion pyrotechnics for laser and electromagnetic interference shielding

The contradiction between flammability and packing density is the technical bottleneck for combustible smoke agent. Herein, polyurethane (PU) foams with flammability and resilience were prepared with polyol and isocyanate as raw materials by chemical foaming method, then compounded with metal powders, polytetrafluoroethylene (PTFE), phthalic annychide (PA), etc. in a certain proportion and pressed into pyrotechnic grain to obtain eco-friendly combustion aerosols with compact density of about 1.15 g/cm³. The resulting combustion smoke agent combined the advantages of PU foam and pyrotechnic with easy ignition, large smoke production, long duration and low environmental pollution. The transmittance of aerosols for 532 nm and 1064 nm lasers was close to 0, and the EMI SE reached up to 65 dB and 35 dB in GPS band and X band, respectively. In addition, the resulting pyrotechnic grains exhibited good mechanical strength and elasticity for sample 1:25, with a compressive strength of 22 MPa and an elastic modulus of 195 MPa. The resulting combustion smoke agent is expected to play a potential role in the field of electromagnetic damage and protection.