Abstract

This study explores the potential of the porous upper portion of oil palm trunk (OPT) as a lightweight, sustainable material for floating platforms. OPT was impregnated with polymethyl methacrylate (PMMA) using a simplified process involving ambient soaking and low-temperature curing, eliminating oven-drying and improving industrial feasibility. The treatment produced tunable densities of 280–450 kg/m³, all within lightweight-material classification. Long-term floating tests showed that higher PMMA loadings substantially improved buoyancy retention over 60 days of submersion, while untreated OPT became nearly fully submerged, indicating that enhanced water resistance effectively compensated for added material weight. Surface characterization revealed that untreated OPT had an initial water contact angle of ~78° that rapidly declined to ~3° within 120 s, whereas heavily treated samples exhibited initial angles near 90° and stabilized around 80°, confirming improved hydrophobicity. ATR-IR spectroscopy, synchrotron tomography, and SEM further verified PMMA deposition, lumen filling, and porosity reduction, collectively illustrating the moisture-barrier mechanism. Mechanical tests under dry and wet conditions further showed increasing modulus of rupture, modulus of elasticity, compressive strength, and screw-withdrawal resistance with polymer content. At 410–450 kg/m³, MOR reached 21 MPa, MOE 2,200 MPa, compressive strength 23 MPa, and screw-withdrawal resistance 580 N. After 30-day water exposure, heavily treated specimens retained over 90% of their strength, while untreated samples degraded substantially. Biofouling tests showed that impregnation reduced colonized surface area from nearly 100% to ~25% after 90 days. Overall, PMMA-treated OPT demonstrates strong potential as a durable and eco-friendly material for floating structures.