Mechanics, optics, and thermodynamics of water transport in chemically modified transparent wood composites

Effects of chemical modification on mechanical, optical, and water transport behavior of transparent wood composites (TWCs1) were investigated. TWCs were produced from a methacrylate resin and balsa wood templates using two delignifying pretreatments, namely lignin-oxidation and lignin-modification, and three interfacial modifications, namely acetylation, methacrylation, and treatment with 2-hydroxyethyl methacrylate. Water transport behavior was investigated via immersion at three temperatures, where diffusion coefficients, kinetic rate constants, and activation energies of water diffusion were obtained. Lignin-modified TWCs were generally more water resistant than lignin-oxidized TWCs. Interfacial modification of the wood template via acetylation and methacrylation were observed to further decrease diffusion coefficients and increase activation energies of diffusion compared to unmodified TWCs, indicating superior fiber-matrix compatibility and improved moisture resistance relative to other tested TWCs. Flexural properties of post-dried TWCs were not adversely affected by moisture compared to samples unconditioned by water. TWC optical properties were measured in pre-immersion, water-saturated, and post-dried states to characterize deterioration of transmittance and haze. While moisture saturation degraded optical properties, optical performance of select TWC classes were observed to rebound upon drying.

Automated summary

The study investigated the effects of chemical modifications on transparent wood composites (TWCs). It was found that lignin-modified TWCs exhibited higher water resistance compared to lignin-oxidized TWCs, and interfacial modifications such as acetylation and methacrylation further improved fiber-matrix compatibility and moisture resistance. The study also showed that optical properties of select TWC classes could rebound upon drying after being degraded by moisture saturation.