Accessibility of hydroxyl groups in birch kraft pulps quantified by deuterium exchange in D2O vapor

Pönni, Raili; Rautkari, Lauri; Hill, Callum A. S.; Vuorinen, Tapani

doi:10.1007/s10570-014-0166-x

Cited by 41 publications

(33 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…(Suchy et al 2010a), this study finds that no or close to no hydroxyls are made inaccessible upon vacuumdrying at 60°C if re-protonation is done with liquid water. Reversibility has previously been reported for cellulosic pulps, but only for alkaline conditions (Pönni et al 2013(Pönni et al , 2014b. Therefore, this is the first study to report nearly full reversibility of deuteration after first drying of native state wood.…”

Section: Hydroxyl Accessibility To Liquid D 2 Omentioning

confidence: 50%

Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

2017

View full text Add to dashboard Cite

The first drying of wood cell walls from the native state has sometimes been described as producing irreversible structural changes which reduce the accessibility to water, a phenomenon often referred to as hornification. This study demonstrates that while changes do seem to take place, these are more complex than what has hitherto been described. The accessibility of wood cell wall hydroxyls to deuteration in the form of liquid water was not found to be affected by drying, since vacuum impregnation with liquid water restores the native cell wall accessibility. Contrary to this, hydroxyl accessibility to deuteration by water vapour was found to decrease to different levels depending on the drying conditions. Vacuum drying at 60°C for 3 days reduced the accessibility more than drying for 1 day at 103°C without vacuum. Drying for 3 days at 103°C increased the hydroxyl accessibility compared to 1 day. Moreover, the decrease in hydroxyl accessibility to deuteration by water vapour induced by the first drying could be at least partially erased by subsequent vacuum impregnation with liquid water, indicating reversibility. For the drying of solid, non-degraded wood cell walls the results challenge the often supposed process of hornification, understood as a permanent decrease in hydroxyl accessibility to water.

show abstract

Section: Hydroxyl Accessibility To Liquid D 2 Omentioning

confidence: 50%

Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

2017

View full text Add to dashboard Cite

show abstract

“…† Since we intended to carry out hydrogen-deuterium exchange at maximum efficiency and reproducibility, we initially dried (using the same setup as presented below) all our cellulose samples so that residual 1 H 2 O was efficiently removed. Indeed, never-dried and dried cellulose have slightly different structures (due to hornification 46,47 ) and, thus, it was important for reasons of consistency to start from a controlled dry condition. The initial drying step lasted for a week, after which we observed no detectable decrease in the sample weight.…”

Section: Materials and Sample Preparationmentioning

confidence: 99%

Water in cellulose: evidence and identification of immobile and mobile adsorbed phases by ²H MAS NMR

Lindh

Terenzi

Salmén

et al. 2017

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The organization of water molecules adsorbed onto cellulose and the supramolecular hydrated structure of microfibril aggregates represents, still today, one of the open and complex questions in the physical chemistry of natural polymers. Here, we investigate by H MAS NMR the mobility of water molecules in carefullyH-exchanged, and thereafter re-dried, microcrystalline cellulose. By subtracting the spectral contribution of deuteroxyls from the spectrum of hydrated cellulose, we demonstrate the existence of two distinct HO spectral populations associated with mobile and immobile water environments, between which the water molecules do not exchange at the NMR observation time scale. We conclude that those two water phases are located at differently-accessible adsorption sites, here assigned to the cellulose surfaces between and within the microfibril aggregates, respectively. The superior performance of H MAS NMR encourages further applications of the same method to other complex systems that expose heterogeneous hygroscopic surfaces, like wood cell walls.

show abstract

“…The reduction of swelling in the control specimens was likely due to hornification (Matsuda et al 1994;Park et al 2006;Rautkari et al 2013). Hornification results in a tightly bound fiber structure in which some of the polar sites previously available for water sorption do not open upon rewetting, decreasing -OH group accessibility (Scallan 1977;Crawshaw and Cameron 2000;Esteban et al 2005;Rautkari et al 2013;Pönni et al 2014). Irreversible hydrogen bonding decreases the capability of water sorption into wood fibers (hygroscopicity).…”

Section: Mass Loss and Dimensional Stability After Re-wetting Cyclesmentioning

confidence: 99%

Analysis of Dimensional Stability of Thermally Modified Wood Affected by Re-Wetting Cycles

Čermák¹,

Rautkari²,

Horáček³

et al. 2015

BioResources

Self Cite

View full text Add to dashboard Cite

The dimensional stability of thermally modified wood exposed to several wetting-drying cycles was analyzed. Specimens of dimensions 15×15 ×15 mm were thermally modified at 180 and 200 °C. The mass loss and chemical composition of the wood were determined in order to evaluate the effect and degree of modification. Afterwards, the radial, tangential, and volumetric swelling, anti-swelling efficiency, water absorption, water repellence efficiency, and mass loss due to wetting-drying cycles were determined and compared. The specimen's mass tended to decrease with each additional rewetting cycle. Additional extractives that were formed via thermal decomposition leached out during wetting cycles. Thermal modification positively affected the dimensional stability of all investigated species. The wood's swelling was reduced, a result attributed to hemicellulose degradation. Dimensional stability was improved by 24 to 30% following mild treatment and by 26 to 54% following more severe treatment. When specimens were exposed to six consecutive rewetting cycles, the swelling of the modified wood increased, whereas it slightly decreased for the control (hornification). The effective dimensional stability of thermally modified wood was reduced by 34 and 28.4% for beech, 47 and 19.6% for poplar, and 19.3 and 24.5% for spruce compared to the initial anti-swelling efficiency following the first wetting cycle.

show abstract

Accessibility of hydroxyl groups in birch kraft pulps quantified by deuterium exchange in D2O vapor

Cited by 41 publications

References 43 publications

Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

Water in cellulose: evidence and identification of immobile and mobile adsorbed phases by ²H MAS NMR

Analysis of Dimensional Stability of Thermally Modified Wood Affected by Re-Wetting Cycles

Contact Info

Product

Resources

About

Accessibility of hydroxyl groups in birch kraft pulps quantified by deuterium exchange in D2O vapor

Cited by 41 publications

References 43 publications

Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

Water in cellulose: evidence and identification of immobile and mobile adsorbed phases by 2H MAS NMR

Analysis of Dimensional Stability of Thermally Modified Wood Affected by Re-Wetting Cycles

Contact Info

Product

Resources

About

Water in cellulose: evidence and identification of immobile and mobile adsorbed phases by ²H MAS NMR