Hydrating softwood and hardwood samples using pure and modified supercritical carbon dioxide

This article describes an in-progress research project that looks to investigate the use of supercritical carbon dioxide (scCO2) for the addition of water to historic and modern, softwood and hardwood samples. The experiments were carried out at 20 MPa and 50 °C, the effects of co-solvent addition, methanol (MeOH), were examined. A three point bend test provided mechanical data for the wood samples treated with both pure and modified scCO2. All the wood samples, with only one exception, saw an increase in Modulus of Rupture (MOR) after being treated with scCO2. Thereby indicating an increased resistance to force in the treated samples. Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy was performed to help deduce if any trends in the OH/CH and OH/Cellulose peak area ratios could be established with the nature of the treatment and the type of wood used. The development of this technique seeks to be relevant and safe for applications within modern conservation practices, where dry and fragile materials are prevalent.