Abstract
Conventional particleboards often exhibit limited mechanical strength, which restricts their use in load-bearing and high-performance applications; reinforcing these boards with carbon fibers offers a potential solution to overcome these limitations. This study investigated the effect of carbon fiber (CF) content on the mechanical performance of single-layer particleboards bonded with polymeric methylene diphenyl diisocyanate (pMDI) adhesive. Carbon fibers were examined as a reinforcement to improve the mechanical properties of particleboards. Experimental boards were produced with 0, 10, 20, 30, 40, and 50% CF (based on the oven-dry mass of wood particles). The analysis included density profile distribution, modulus of rupture (MOR), modulus of elasticity (MOE), and screw withdrawal resistance (SWR). The results showed that mechanical performance improved only at lower CF contents. The most pronounced effect was observed at 10% CF, where MOR increased from 15.2 MPa (control) to 19.2 MPa, and MOE increased from 2.45 GPa to 2.91 GPa. Higher CF additions (≥20%) did not yield further improvements, and at elevated levels (≥30%), bending performance decreased (MOR dropped to 14.1–13.5 MPa) due to poor fiber dispersion and weakened interfacial bonding between fibers and wood particles. Screw withdrawal resistance increased gradually with CF content, from 156 N in the control boards to 182 N at 50% CF, although the improvement was limited by adhesion quality and mat heterogeneity. Overall, the study demonstrates that small CF additions can enhance selected mechanical properties of particleboards, whereas higher loadings negatively affect performance due to microstructural incompatibilities.