Date palm wood-based foams with gellan gum binder for enhanced sound and thermal insulation in building applications

Abstract

Biofoams are a promising alternative to fossil-fuel-derived materials for heat insulation in construction. However, the processing of biomaterials to produce bioaerogels involves multistep steps, making it costly and complicated. In this study, biofoams were fabricated from biomass without any prior treatment through a simple process. Wood powder obtained from date palm waste was suspended in an aqueous gellan gum solution, gelled, and then freeze-dried. A major advancement in this study is the absence of any chemical treatment or crosslinking agents. In addition, to the best of our knowledge, this study is the first to fabricate wood foams using gellan gum. The wood powder obtained from biomass was added to a 1 wt.% aqueous gellan gum solution at concentrations of 2, 3, 4, and 5 wt.% (relative to the mass of the solution). Increasing wood loading from 2 to 5 wt.% raised foam density from 62.68 to 89.44 kg/m³, thermal conductivity from 0.019 to 0.047 W/m·K, and thermal diffusivity from 0.05 to 0.37 mm²/s, while compressive strength at 50% strain rose sharply from 36 kPa at 2 wt.% to 95 kPa at 5 wt.%, indicating a clear trade-off between thermal insulation performance and mechanical strength governed by biomass content. Specific heat capacity followed the inverse trend, decreasing as wood loading increased. The 2 wt.% formulation achieved the lowest density and thermal conductivity values recorded in this study, along with the highest sound absorption coefficient (0.75), identifying it as the most promising composition for thermal and acoustic insulation applications, whereas higher-loading formulations may better suit applications prioritizing compressive strength. The fabricated materials were further characterized using a smoke density tester, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis, confirming the foams' porous structure and thermal stability. The findings of this study demonstrate the high potential for using date palm wood waste as a low-cost, eco-friendly, tunable thermal insulation material in construction, with composition offering a direct route to tailor performance for specific end-use requirements.