Chitin nanocrystals as bio-based adhesives for the development of sustainable cork composites

In this work, we demonstrate the potential of chitin nanocrystals (ChNCs), a sustainable and biobased nanomaterial, as an adhesive for valorizing cork waste and fabricating fully biobased composites through compression molding. SEM and XCT analyses confirmed that, when used at concentrations below 30 wt.%, ChNCs integrate homogeneously with cork by adhering uniformly to the cork cell walls, preserving its low density and inherent flexibility. Notably, composites containing 20 wt.% of ChNCs achieved superior mechanical properties (i.e. flexibility, strength and toughness) compared to composites with paraffin over a broad concentration range (5–70 wt.%). Unlike paraffin, which increases density by filling the cork cells, ChNCs maintain the porous structure while significantly enhancing compressive performance. These findings highlight the exceptional adhesive and reinforcing capabilities of ChNCs, paving the way for their use as a natural binder in developing sustainable cork composites and extending this approach to other agrowaste materials.