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Title: Delineating pMDI model reactions with loblolly pine via solution state NMR spectroscopy. Part2.Non-catalyzed reactions with the wood cell wall

Source: Holzforschung, Vol. 65, pp. 145-154, 2011

Author(s)Yelle, Daniel J.; Ralph, John; Frihart, Charles R.

Publication Year: 2011  View PDF »

Category: Journal Articles
Associated Research Project(s):   FPL-4707-3A

Abstract: Solution-state NMR provides a powerful tool to observe the presence or absence of covalent bonds between wood and adhesives. Finely ground wood can be dissolved in an NMRcompatible solvent system containing dimethylsulfoxide-d6 and N-methylimidazole-d6, in which the wood polymers remain largely intact. High-resolution solution-state twodimensional NMR correlation experiments, based on 13C-1H one-bond heteronuclear single quantum coherence, allow structural analysis of the major cell wall components. This technique was applied to loblolly pine that was treated with polymeric methylene diphenyl diisocyanate (pMDI) related model compounds under controlled moisture and temperature conditions. Chemical shifts of carbamates formed between the pMDI model compounds and loblolly pine were determined. The results show that: (a) under dry conditions and a high concentration of isocyanate, carb tes will form preferentially with side-chain hydroxyl groups on b-aryl ether and phenylcoumaran-linked lignin units in a swelling solvent; (b) phenyl isocyanate is more capable of derivatization in the cell wall than the bulkier 4-benzylphenyl isocyanate; (c) at 5% and 14% moisture content, detectable carbamates on lignin side-chains dramatically decrease; and (d) under typical conditions of industrial oriented strandboard production in a hot press at 5% and 14% moisture content, no carbamate formation was detected.

Keywords: Isocyanates, adhesives, glue, testing, plant cell walls, adhesion, hydroxyl group, chemical reactions, nuclear magnetic resonance spectroscopy, loblolly pine, lignin analysis, wood chemistry, carbamates, moisture, temperature, solvents, particle board, chemical composition, polymeric methylene diphenyl diisocyanate, pMDI, bonding, wood bonding, phenyl isocyanate, phenylcoumarin, polymers, polymerization, moisture content, oriented strandboard, OSB, earlywood, pinus taeda

Publication Review Process: Formally Refereed

File size: 555 kb(s)

Date posted: 03/29/2011

This publication is also viewable on Treesearch:  view
RITS Product ID: 37767
Current FPL Scientists associated with this product (listed alphabetically)
Frihart, Charles R.
Research Chemist
Yelle, Daniel
Research Forest Products Technologist
 

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