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Ghorbani, M; Konnerth, J; Budjav, E; Silva, AR; Zinovyev, G; van Herwijnen, HWG; Edler, M; Griesser, T; Liebner, F.
(2017): Ammoxidized Fenton-Activated Pine Kraft Lignin Accelerates Synthesis and Curing of Resole Resins
POLYMERS-BASEL. 2017; 9(2): FullText FullText_BOKU

Ammoxidation of pine kraft lignin in aqueous 5 wt % ammonia affords a novel type of phenol substitute that significantly accelerates resole synthesis and curing as demonstrated for 40 wt % phenol replacement. Compared to non-ammoxidized lignin, which already shortens significantly the cooking time required to reach a resole viscosity of 1000 Pa . s (250 vs. 150 s) and reduces the typical curing B-time by about 25% at 100 degrees C, the use of ammoxidized lignin has an even more pronounced impact in this respect. Activation of lignin by Fenton-type oxidation prior to ammoxidation further boosts both synthesis and curing of the resole. This is presumably due to the intermediary formation of polyvalent cross-linkers like N, N, N-tris (methylol) trimethylene triamine triggered by saponification of a larger fraction of nitrogenous moieties present in such a treated lignin (ammonium salts, amide-type nitrogen, urea) and reaction of the released ammonia with formaldehyde. Except for the fact that phenol replacement by ammoxidized lignin results in a somewhat less brittle cured adhesive polymer and higher elastic modulus, the aforementioned acceleration in curing could no longer be observed in the presence of wood, where a significantly delayed wood-adhesive bond formation was observed for the lignin-containing adhesives as evident from the automated bonding evaluation system.
Authors BOKU Wien:
Budjav Enkhjargal
Ghorbani Masoumeh
Konnerth Johannes
Liebner Falk
Zinovyev Grigory
BOKU Gendermonitor:

Find related publications in this database (Keywords)
phenol formaldehyde resin
lignin ammoxidation
Fenton-type oxidation
ligneous adhesive
automated bonding evaluation system (ABES)

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