The pursuit of sustainable insulating materials demands overcoming a fundamental compromise: enhancing thermal resistance often compromises mechanical strength. We hypothesize that nanocellulose, with its high aspect ratio and functional surface, can tackle this dual challenge within a castor oil rigid polyurethane matrix by simultaneously templating fine, insulating and reinforcing cell walls. To test this, we engineered a series of rigid foams with varying nanocellulose content (5–20 wt%), using water as a green blowing agent (water-based CO 2 generation 2 wt.%). Advanced characterization (FTIR, XRD, EDS, SEM, TGA/DTG, thermal conductivity analysis (TCA)) reveals that nanocellulose acts as a dual-agent: (i) it nucleates a remarkably uniform closed-cell morphology (cell size distribution reduced by 65%), directly responsible for a 19% reduction in thermal conductivity (λ-value); and (ii) it forms a percolating network that reinforces the polymer struts, leading to a 10–15% increase in compressive strength. This work moves beyond filler incorporation to demonstrate a validated nano-architectural strategy for decoupling thermal and mechanical properties, providing a blueprint for designing next-generation, high-performance bio-based insulating composites.
Bennesser et al. (Sat,) studied this question.