abstract
Supercritical dyeing of wood is a smart green technology. Beyond being of interest to wood industry, it could help to preserve tropical forests and decrease the environmental pollution from overseas shipping. However, scCO(2) dyeing is still in its infancies. This paper demonstrates at the example of three major European hardwood species and the dye Naphthazarin that the uptake of colorants can be improved if scCO(2) is complemented with small amounts of DMSO. The latter triggers micro-swelling of wood, thereby improving dye penetration. Systematic variation of process parameters revealed that optimal colouration is reached at 20.0 MPa and 85 degrees C. Colour gradients as observed in the interior of halved specimen were evaluated by two methods. While the Euclidean distance Delta E (CIELAB) represents relative colour change only, a recently proposed scanning densitometric approach translates colour depth into absolute dye surface concentration. Morphological investigations conceal this study investigating the impact of selected process conditions. (C) 2020 The Authors. Published by Elsevier B.V.
keywords
SUPERCRITICAL-FLUID IMPREGNATION; REACTIVE DISPERSE DYES; INTERNAL-PRESSURE DEVELOPMENT; CELLULOSIC KEY CHROMOPHORE; CARBON-DIOXIDE; COTTON; FIBERS; CO2; ACETYLATION; BIOCIDES
subject category
Chemistry; Engineering
authors
Jaxel, J; Gusenbauer, C; Bohmdorfer, S; Liebner, F; Hansmann, C
Groups
acknowledgements
Authors are grateful to Dr. Stefan Frybort and Peter Bliem for technical help with the three-point bending tests. The financial support by FFG - The Austrian Research Funding Agency through the BRIDGE project Dyeing of massive wood mediated by supercritical CO