Inspired by the load-bearing principles of architectural diagonal bracing systems, this study proposes a novel strategy for constructing multifunctional, porous cellulose scaffolds through the synergistic integration of long and short fibers with borax cross-linking. A three-dimensional fireproof network is fabricated via an anionic surfactant-assisted mechanical foaming process. Within this architecture, long softwood (SW) fibers serve as the primary load-bearing skeleton, while short, highly fibrillated hardwood (HW) fibers function as diagonal braces, stabilizing pore walls and enhancing structural integrity to achieve an optimal balance of strength and toughness. At an optimized HW/SW mass ratio of 7:3, the scaffold exhibits superior cushioning performance, achieving a maximum compressive stress of 127.62 kPa, a minimum acceleration of 72.37 m/s2, and a minimal cushioning coefficient of 5.79. Furthermore, borax cross-linking significantly enhances flame retardancy by promoting a condensed-phase mechanism, evidenced by a substantial increase in char residue to 22.9% at 800 °C. The highly tortuous porous network also provides excellent thermal insulation. This work presents a facile and sustainable fabrication route for biobased foams with integrated impact buffering, thermal shielding, and fire-resistant properties, demonstrating significant potential for advanced applications in sustainable protective packaging and thermal insulation materials.
Song et al. (Mon,) studied this question.