TY  - JOUR
U1  - Zeitschriftenartikel, wissenschaftlich - begutachtet (reviewed)
A1  - Klein, Stephanie Elisabeth
A1  - Rumpf, Jessica
A1  - Kusch, Peter
A1  - Albach, Rolf
A1  - Rehahn, Matthias
A1  - Witzleben, Steffen
A1  - Schulze, Margit
T1  - Unmodified kraft lignin isolated at room temperature from aqueous solution for preparation of highly flexible transparent polyurethane coatings
JF  - RSC Advances
N2  - Polyurethane (PU) coatings were successfully produced using unmodified kraft lignin (KL) as an environmentally benign component in contents of up to 80 wt%. Lignin samples were precipitated from industrial black liquor in aqueous solution working at room temperature and different pH levels (pH 2 to pH 5). Lignins were characterized by UV-Vis, FTIR, pyrolysis-GC/MS, SEC and 31P-NMR. Results show a correlation between pH level, OH number and molecular weight Mw of isolated lignins. Lignin-based polyurethane coatings were prepared in an efficient one step synthesis dissolving lignin in THF and PEG425 in an ultrasonic bath followed by addition of 4,4-diphenylmethanediisocyanate (MDI) and triethylamine (TEA). Crosslinking was achieved under very mild conditions (1 hour at room temperature followed by 3 hours at 35 °C). The resulting coatings were characterized regarding their physical properties including ATR-IR, TGA, optical contact angle, light microscopy, REM-EDX and AFM data. Transparent homogeneous films of high flexibility resulted from lignins isolated at pH 4, possessing a temperature resistance up to 160 °C. Swelling tests revealed a resistance against water. Swelling in DMSO depends on index, pH of precipitation and catalyst utilization for PU preparation. According to AFM studies, surface roughness is between 10 and 28 nm.
UN  - https://nbn-resolving.org/urn:nbn:de:hbz:1044-opus-43290
SN  - 2046-2069
SS  - 2046-2069
U6  - https://doi.org/10.1039/C8RA08579J
DO  - https://doi.org/10.1039/C8RA08579J
PM  - 35557904
VL  - 8
IS  - 71
SP  - 40765
EP  - 40777
PB  - Royal Society of Chemistry (RSC)
ER  -