Fabrication and Thermal Conductivity of Boron Nitride Nano Barb/Acrylic Polymer Nanocomposites

The effect of manual mortar-grinding pretreatment on the thermal and mechanical properties of Boron Nitride Nano Barb (BNNB)-filled acrylic polymer composites was investigated. Composites incorporated with 5 wt.% (≈3 vol.%) of either virgin or mechanically fractured (shattered) BNNB were fabricated via hot-pressing of a thermoplastic acrylic resin at 230°C under 96 MPa for 90 min. Vickers hardness increased from 20.4 HV for neat acrylic to 29.2 HV (+43.1%) for the shattered BNNB composite, which is attributed to the omnipresent activation of barb-mediated mechanical interlocking within the polymer matrix. Thermal conductivity improved by 18.1% and 34.7% relative to neat acrylic for the Acrylic/Virgin BNNB and Acrylic/Shattered BNNB composites, respectively. The superior thermal performance is attributed to a phonon bridging network formed through barb-mediated contact between dispersed BNNB fragments, supported by experimental values exceeding Lewis–Nielsen model predictions. These results demonstrate that simple manual grinding simultaneously enhances mechanical and thermal properties without chemical surface modification, offering a practical strategy for thermally conductive polymer composite design.