Moisture-related changes in the nanostructure of woods studied with X-ray and neutron scattering

Penttilä, Paavo A.; Altgen, Michael; Carl, Nico; Linden, P. van der; Morfin, Isabelle; Österberg, Monika; Schweins, Ralf; Rautkari, Lauri

doi:10.1007/s10570-019-02781-7

Cited by 47 publications

(47 citation statements)

References 44 publications

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“…72 h could not restore the initial hygroscopicity in the never-dried state completely. This was in line with the observations by Penttilä et al (2020), who found that drying and re-soaking wood samples in liquid water resulted in lower moisture contents at ca. 89% RH compared to never-dried samples for different soft-and hardwood species.…”

Section: Sorption Isotherms and Hysteresissupporting

confidence: 93%

Humidity-dependence of the hydroxyl accessibility in Norway spruce wood

Altgen

Rautkari

2020

Cellulose

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This study aimed at a better understanding of the wood-water interaction, in particular the role of the hydroxyl accessibility during the humidity-dependent change in moisture content. Thin sections (80 µm) of never-dried Norway spruce sapwood that contained early- and latewood were used for the experiments. Sorption isotherm measurements confirmed the humidity-dependent moisture content changes and the effect of the first drying of the wood sections. Changes in hydroxyl accessibility were then determined by deuteration of the sections using deuterium oxide, followed by their re-protonation in water (H2O) vapor at different relative humidity: 15, 55 or 95%. The deuteration and re-protonation of the wood sections were quantified by dry mass changes as well as by changes in the OH and OD stretching vibrations in the Fourier transform infrared spectra. The results showed that the deuterated sections could be almost completely re-protonated in H2O vapor, nearly irrespective of the applied relative humidity. Therefore, changes in hydroxyl accessibility were not the driving force for the humidity-dependent changes in moisture content. However, a slow re-protonation rate at low relative humidity had to be considered. Nonetheless, a small quantity of OD groups persisted the re-protonation in H2O vapor and liquid H2O, which was not related to the drying of the wood. Graphic abstract

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Section: Sorption Isotherms and Hysteresissupporting

confidence: 93%

Humidity-dependence of the hydroxyl accessibility in Norway spruce wood

Altgen

Rautkari

2020

Cellulose

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“…In this study, the WAXS (i.e., Scherrer) analysis gave larger values regarding the average cellulose crystallite widths than the SAXS analysis regarding the diameters of cylinders presenting the elementary cellulose microfibrils. A similar discrepancy has been detected also earlier (Jakob et al 1995;Leppänen et al 2009;Penttilä et al 2019Penttilä et al , 2020. The larger crystallite widths obtained by WAXS can be explained by the aggregation of the elementary cellulose microfibrils (Jarvis 2018).…”

Section: Comparison Between Waxs and Saxs Results Of The Cellulose MIsupporting

confidence: 77%

“…This would also explain the larger role of the Gaussian term because this term could arise from the scattering from the nanosized pores of the G-layer. This interpretation and the related observations are strengthened by the results of beech TW measured by SAXS and small-angle neutron scattering (SANS) by Penttilä et al (2020) and the results of poplar TW measured by SANS by Sawada et al (2018).…”

Section: Saxs Resultsmentioning

confidence: 83%

“…This corresponds to the previous observations by, e.g., Sawada et al (2018) that the coalescence of the elementary microfibrils is common in TW, which also explains the large crystallite widths by WAXS. It should be noted, that the WoodSAS fits for these TW samples could also be conducted using larger values of interfibrillar distance (4-6 nm) based on the values presented for beech TW by Penttilä et al (2020). Based on the goodness of fit values, the fits were slightly better in the case of smaller interfibrillar distance values and thus they are given in Table 2.…”

Section: Saxs Resultsmentioning

confidence: 99%

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Ultrastructural X-ray scattering studies of tropical and temperate hardwoods used as tonewoods

Viljanen

Ahvenainen

Penttilä

et al. 2020

IAWA J.

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The structure of hardwoods representing eight tropical and five temperate species was characterized from the atomistic level up to the cellular level using X-ray scattering, X-ray microtomography and light microscopy. The species were chosen for this study based on their popularity as tonewoods. The ultrastructure of wood cell walls, including crystallite size, orientation and close-range order of cellulose microfibrils were determined by small- and wide-angle X-ray scattering (SAXS, WAXS). The SAXS patterns were interpreted by using an analytical model of cylinders packed in a hexagonal close-range order with paracrystalline distortion. The values for the cylinder diameters given by this model were compared to the average crystallite widths obtained by WAXS using the Scherrer equation. In six out of 26 samples, all of these representing tropical species used especially in fretboard parts of electric guitars, large differences between these two sizes were obtained. The WAXS and microscopy results of these samples corresponded to tension wood structures. These comparisons and interpretations of SAXS results have not been previously presented for any tropical hardwoods, especially related to those containing tension wood tissue. The importance of the ultrastructural characterization was highlighted in this study in the case of tropical hardwood samples.

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“…The differences caused by PEG were less dramatic but still significant in birch wood, which was the only representative of hardwoods in this study. This might be related to the overall smaller wet-state interfibrillar distance reported for hardwoods based on SANS and SAXS data 22,28,34 . In general, the results support previous findings from pulp www.nature.com/scientificreports/ fibers 17 , according to which the PEG molecules mostly occupy the spaces between microfibril bundles, but are not able to penetrate into the polymeric matrix between the individual microfibrils.…”

Section: Sans Reveals the Microfibril Bundlesmentioning

confidence: 93%

Bundling of cellulose microfibrils in native and polyethylene glycol-containing wood cell walls revealed by small-angle neutron scattering

Penttilä

Altgen

Awais

et al. 2020

Sci Rep

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Wood and other plant-based resources provide abundant, renewable raw materials for a variety of applications. Nevertheless, their utilization would greatly benefit from more efficient and accurate methods to characterize the detailed nanoscale architecture of plant cell walls. Non-invasive techniques such as neutron and X-ray scattering hold a promise for elucidating the hierarchical cell wall structure and any changes in its morphology, but their use is hindered by challenges in interpreting the experimental data. We used small-angle neutron scattering in combination with contrast variation by poly(ethylene glycol) (PEG) to identify the scattering contribution from cellulose microfibril bundles in native wood cell walls. Using this method, mean diameters for the microfibril bundles from 12 to 19 nm were determined, without the necessity of cutting, drying or freezing the cell wall. The packing distance of the individual microfibrils inside the bundles can be obtained from the same data. This finding opens up possibilities for further utilization of small-angle scattering in characterizing the plant cell wall nanostructure and its response to chemical, physical and biological modifications or even in situ treatments. Moreover, our results give new insights into the interaction between PEG and the wood nanostructure, which may be helpful for preservation of archaeological woods.

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Moisture-related changes in the nanostructure of woods studied with X-ray and neutron scattering

Cited by 47 publications

References 44 publications

Humidity-dependence of the hydroxyl accessibility in Norway spruce wood

Humidity-dependence of the hydroxyl accessibility in Norway spruce wood

Ultrastructural X-ray scattering studies of tropical and temperate hardwoods used as tonewoods

Bundling of cellulose microfibrils in native and polyethylene glycol-containing wood cell walls revealed by small-angle neutron scattering

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