Performance of rubberwood-pine particleboards bonded with castor-oil polyurethane and their numerical application as stiffening layers for glass fiber-reinforced polymer (GFRP) roofing sheets

This study evaluated the physical–mechanical performance of particleboards produced with wood particles from Hevea brasiliensis and Pinus taeda and a castor oil-based polyurethane adhesive (PUR), with the purpose of assessing the influence of the progressive replacement of Pinus taeda wood particles by Hevea brasiliensis particles on the physical and mechanical properties investigated. Three compositions were manufactured: H100 (100% Hevea brasiliensis and 0% Pinus taeda), H70 (70% Hevea brasiliensis and 30% Pinus taeda ), and H0 (0% Hevea brasiliensis and 100% Pinus taeda ), and the composites were characterized according to the provisions and calculation procedures of ABNT NBR 14810, in addition to using ANSI A208.1 to assess performance requirements. Statistical analysis showed that the 100% Pinewood mixture presented the best results for bending strength (MOR = 16.84 MPa) and modulus of elasticity (MOE = 2352 MPa), whereas the 100% Hevea mixture resulted in the best performance in internal bond strength (IB), moisture content, and dimensional stability. All compositions simultaneously met the normative requirements. In a subsequent stage, numerical simulations (14 in total) were developed to evaluate the potential application of the H70 composition to the mechanical performance of commercially produced glass-fiber-reinforced polyester (GFRP) roofing sheets. This composition was selected due to its balance between satisfactory performance and a more sustainable raw-material composition, with partial replacement of highly demanded pinewood by rubberwood residue. The simulations were conducted to assess the stiffness of the combined materials when subjected to bending loads. The simulation results showed that combining the manufactured composite with the GFRP significantly reduced the maximum displacements (deflections) by approximately 96% for the two panel thicknesses analyzed (2 cm and 3 cm), compared with simulations considering only the contribution of the GFRP. Therefore, it is concluded that the proposed system (particle-based composite and GFRP) is technically feasible, lightweight, and sustainable, with potential application in roofing systems.