Study of the Leaching of Low-Molecular-Weight Molecules from Wood-Reinforced Unsaturated Polyester Composites Using UV-Vis Spectroscopy and Gas Chromatography-Mass Spectrometry.

Wood is a sustainable and renewable resource whose various uses include heating and manufacturing of various components for different sectors. The ever-increasing global demand for wood necessitates expanding the lifetime of wood products by reusing or recycling the wood into new products, for example in wood composites. To make the case for using preservative-treated wood to produce composites, this study investigates the capability of an unsaturated polyester matrix to encapsulate low-molecular-weight molecules. Ultraviolet-visible (UV-Vis) spectroscopy and gas chromatography-mass spectrometry (GC-MS) were used to study the leaching behaviour from wood composites upon storage in water. In a first step, the wood used for the wood composites was treated with UV-active model compounds (uranine and Nile red), combined with resin to make wood composites, and their leaching into water was determined by UV-vis spectroscopy. In the GC-MS study, a similar experimental setup was used to study the leaching of wood preservatives (tebuconazole, propiconazole, and permethrin) over time from wood composites. The leaching of the wood preservatives from the wood composites upon water storage was assessed and quantified using GC-MS. The study found that the majority of the studied compounds only leach to a very small extent from the wood composites. Possible reasons for variations in leaching behaviour are discussed. These findings are an important first step in the endeavour of reusing contaminated wood in wood composites.