Modified hollow glass microsphere isocyanate-based polyimide foam composite with improved mechanical and thermal insulation properties

In this work, hollow glass microspheres (HGM) were introduced into the polyimide matrix as an effective reinforcement filler to improve the mechanical and thermal insulation properties of the polyimide foams (PIF). The HGM was surface-modified with the silane coupling agent to enhance the interfacial compatibility with PIF. Experimental results revealed that the average cellular diameter of PIF decreased obviously with the addition of the modified HGM (M-HGM). The apparent density of foams also increased from 15.85 to 18.34 kg/m³ when the M-HGM combination was changed from 0 to 12 percent (wt.%). Compared with the pure PIF, the composite foams added 8 wt.% M-HGM showed high compression strength (65 kPa) and compression modulus (1147 kPa), resulting in a distinct enhancement in mechanical properties. Furthermore, the addition of M-HGM filler also improved the thermal insulation performance of PIF, which exhibited the minimum thermal conductivity of 29.48 mW·m⁻¹·K⁻¹ with 8 wt.% M-HGM. Thus, considering the improved mechanical and insulation properties of the prepared PIF, it could be a promising candidate for the high temperature-resistant thermal insulating applications.