Characterization of moisture in acetylated and propionylated radiata pine using low-field nuclear magnetic resonance (LFNMR) relaxometry

TY - JOUR

T1 - Characterization of moisture in acetylated and propionylated radiata pine using low-field nuclear magnetic resonance (LFNMR) relaxometry

AU - Beck, Greeley

AU - Thybring, Emil Engelund

AU - Thygesen, Lisbeth Garbrecht

AU - Hill, Callum

PY - 2018/2/23

Y1 - 2018/2/23

N2 - Moisture in radiata pine (Pinus radiata D. Don) earlywood (EW), which was acetylated or propionylated to various degrees, was measured by low-field nuclear magnetic resonance (LFNMR) relaxometry. Spin-spin relaxation times (T2) were determined for fully saturated samples at 22 and -18°C. T2 values for EW lumen water increased with increasing acetylation weight percentage gain (WPG), perhaps caused by the less hydrophilic acetylated wood (AcW) surface. Cell wall water (WCW) and the water in pits and small voids also showed increasing T2 values as a function of WPG but with a weaker tendency. A possible explanation is the counteracting effects of decreased hydrophilicity and reduced moisture content (MC) of these water populations at higher levels of acetylation. The evaluation of propionylation on WCW T2 data was complicated by peak splitting in the relaxation spectrum. Constant T2 values for void water populations at various WPG levels for propionylated samples indicate a modification gradient in the cell wall. Fiber saturation point (FSP) was significantly reduced by both modifications. Slightly higher FSP values for propionylated samples suggest that physical bulking is not the only factor causing moisture exclusion in AcW. But this interpretation is tentative because of the possibility of cell wall damage caused by propionylation.

AB - Moisture in radiata pine (Pinus radiata D. Don) earlywood (EW), which was acetylated or propionylated to various degrees, was measured by low-field nuclear magnetic resonance (LFNMR) relaxometry. Spin-spin relaxation times (T2) were determined for fully saturated samples at 22 and -18°C. T2 values for EW lumen water increased with increasing acetylation weight percentage gain (WPG), perhaps caused by the less hydrophilic acetylated wood (AcW) surface. Cell wall water (WCW) and the water in pits and small voids also showed increasing T2 values as a function of WPG but with a weaker tendency. A possible explanation is the counteracting effects of decreased hydrophilicity and reduced moisture content (MC) of these water populations at higher levels of acetylation. The evaluation of propionylation on WCW T2 data was complicated by peak splitting in the relaxation spectrum. Constant T2 values for void water populations at various WPG levels for propionylated samples indicate a modification gradient in the cell wall. Fiber saturation point (FSP) was significantly reduced by both modifications. Slightly higher FSP values for propionylated samples suggest that physical bulking is not the only factor causing moisture exclusion in AcW. But this interpretation is tentative because of the possibility of cell wall damage caused by propionylation.

KW - acetylation

KW - cryo-relaxometry

KW - fiber saturation point (FSP)

KW - low-field nuclear magnetic resonance (LFNMR)

KW - modified wood

KW - moisture content

KW - propionylation

KW - spin-spin relaxation time (T)

U2 - 10.1515/hf-2017-0072

DO - 10.1515/hf-2017-0072

M3 - Journal article

AN - SCOPUS:85037605031

SN - 0018-3830

VL - 72

SP - 225

EP - 233

JO - Holzforschung

JF - Holzforschung

IS - 3

ER -