Development of BaSO 4 -containing bamboo–water hyacinth particleboards using castor oil-based polyurethane adhesive: effects of particle structure on mechanical, acoustic, thermal, fire, and radiation-shielding performance

This study developed multifunctional bamboo–water hyacinth particleboards containing 10 wt% barium sulfate (BaSO4) and a castor oil-based polyurethane adhesive, using particle-size engineering and layered structural design. Six formulations (B5, B50, W5, W50, BWB, and WBW) were manufactured and evaluated for mechanical, thermal, acoustic, fire-resistance, and radiation-shielding performance. Results showed that particle composition, particle size, and layer arrangement significantly affected board performance. Mechanical properties varied considerably, with modulus of rupture, modulus of elasticity, internal bond strength, and surface soundness ranging from 20.90–31.78 MPa, 5,200–10,090 MPa, 0.23–0.72 MPa, and 0.17–0.75 MPa, respectively. Thermal conductivity ranged from 0.1120 to 0.1469 W/m·K, while thermal resistance ranged from 0.0616 to 0.0873 m2K/W. The highest sound absorption coefficient, 0.97, was achieved at high frequencies, particularly in multilayer configurations. TG/DTG analysis revealed multistage degradation behaviour, with the major degradation occurring between 320 and 360°C. All formulations satisfied the UL-94 V-0 afterflame time criterion. Radiation-shielding performance under the investigated laboratory conditions was demonstrated by linear attenuation coefficients of 0.22–0.28 cm−1 at 81 keV and thermal-neutron shielding rates of up to 71.0% at a thickness of 6 cm. These findings demonstrate the potential of bamboo–water hyacinth particleboards with fixed BaSO4 content as sustainable, multifunctional materials for interior building components and supplementary shielding applications.