Multifunctional transparent wood: Systematic study of morphology, color, and damping

High-performance transparent polymers are of great interest in the automotive and electronics industries, but conventional plastics lack mechanical strength, while high-performance systems are generally opaque. In this study, polyvinyl alcohol (PVA)-based transparent wood composites were fabricated from beech, maple, and poplar via delignification and vacuum-assisted infiltration. The resulting composites exhibited light transmittance values of 83.5% (beech-PVA), 20.5% (poplar-PVA), and 5.4% (maple-PVA), with corresponding haze values of 95.9%, 95.9%, and 82.9%, respectively. Linear regression models established strong correlations between optical properties and Hunter color parameters: haze versus lightness (R 2 = 0.82) and haze versus yellowness (R 2 = 0.80), enabling targeted optical design. PVA infiltration achieved the lowest yellowness (b = +11 to +13) reported for additive-free transparent wood composites, producing a near-neutral, glass-like appearance. Electron microscopy confirmed complete pore filling and nanoscale PVA penetration into the cell walls, forming a dense hydrogen-bonded network. This interaction produced exceptional viscoelastic behavior: beech-PVA achieved a glass transition temperature of 169.2°C, while maple-PVA exhibited the broadest damping among transparent wood composites (tan δ > 0.27 from 20°C to 95°C). These thermomechanical characteristics, combined with tunable haze through color control, make this material ideal for hot climates requiring heat management and visual comfort. PVA-based transparent wood functions as a natural “smart surface,” paving the way for sustainable, shock-resistant construction materials derived entirely from biological sources.