Hybrid Particleboards from Sargassum, Sugarcane Bagasse and Residual HDPE for Sustainable Building Applications

Large-scale and recurrent Sargassum beaching events along the coastlines of Brazil, Mexico, and the Caribbean pose significant environmental, social, and economic challenges due to biomass accumulation and decomposition. Meanwhile, valorization of underutilized waste streams into composite materials can advance circular economy strategies. Building upon previous findings on Sargassum-based particleboards, this study investigated increased pressing temperature and residual high-density polyethylene (HDPE) incorporation as strategies to improve dimensional stability. Medium-density particleboards were manufactured from Sargassum biomass and sugarcane bagasse, with and without residual HDPE, using bio-based castor oil polyurethane resin. The panels were characterized regarding physical, mechanical, and thermal properties to assess their suitability for non-structural applications. HDPE-containing formulations showed reduced 24 h thickness swelling from 21% to 15%, while exhibiting an overall reduction in mechanical performance, particularly in bending and internal bond strength properties. Despite this trade-off, the developed particleboards demonstrated potential for furniture and indoor building applications while simultaneously valorizing marine, agro-industrial, and plastic residues. These findings support Sargassum biomass as a sustainable feedstock for particleboard production and indicate that residual HDPE can improve 24 h thickness swelling performance, contributing to circular economy strategies and low-impact material development for applications across the built environment sector.