A Polyimide/Hollow Glass Microsphere Composite Film with High Mechanical Properties for Thermal Insulation

As modern industry develops rapidly, the demand for thermal insulation materials with tailored mechanical and thermal insulation properties has increased significantly. In this work, hollow glass microspheres (HGM) were deposited on polyimide (PI) via spraying to fabricate a “PI matrix/HGM surface-laminated” composite structure, which successfully resulted in high-strength, thermally insulating PI/HGM-S films. The tensile strength of these films reaches up to 176.5 MPa, which is a 109.6% increase compared to PI/HGM-B films prepared via the traditional blending method. This effectively overcomes the bottleneck of inadequate mechanical properties in conventional thermal insulation materials. This high mechanical performance stems from the spraying process, which mechanically attaches HGM to the PI surface. Unlike the blending method (filler dispersion inside the matrix causes stress concentration and defects), the spraying process preserves the structural integrity of the PI matrix. Meanwhile, a dual gas-phase entrapment mechanism (via HGM hollow structures and interparticle pores) reduces the thermal conductivity to 0.081 W·m–1·K–1, realizing the synergistic optimization of mechanical and thermal insulation properties. The dual advantages of high strength and low thermal conductivity make PI/HGM-S films suitable for thermal insulation applications requiring strict mechanical performance, offering a material solution to ensure equipment reliability and stability under high-temperature conditions.