Sustainable components for polyurethane coatings
Scientists have studied the antioxidative capacity of four different kraft lignins (KL) and one additional organosolv lignin (OSL) using the Folin–Ciocalteu (FC) assay.
To do so, the corresponding FC assay procedure was adapted and optimised to be appropriate for lignin analysis. Different solvents were tested, and DMSO and saturated sodium carbonate (Na2CO3) for pH adjustment showed the best results. The absorption wavelength of 740 nm was chosen due to highest determination coefficients.
Higher antioxidant activity for kraft vs organosolv lignins
The antioxidant capacity and related radical scavenging activity of various lignins were correlated with the biomass nature (soft wood vs grasses) and pulping methods (kraft vs organosolv). The results show higher antioxidant activity for kraft vs organosolv lignins. First lignin-derived polyurethane coatings were prepared using the unmodified kraft lignin. The films, prepared via spin coating, show a high flexibility and transparency.
The study can be found in Journal of Coatings Technology and Research, Volume 16.
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