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

TY - JOUR

T1 - Hydroxyl accessibility in wood cell walls as affected by drying and re-wetting procedures

AU - Thybring, Emil Engelund

AU - Thygesen, Lisbeth Garbrecht

AU - Burgert, Ingo

PY - 2017/6/1

Y1 - 2017/6/1

N2 - 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.

AB - 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.

KW - ATR-FTIR

KW - Deuterium exchange

KW - DVS

KW - Hydroxyl accessibility

KW - Wood

U2 - 10.1007/s10570-017-1278-x

DO - 10.1007/s10570-017-1278-x

M3 - Journal article

AN - SCOPUS:85016477392

SN - 0969-0239

VL - 24

SP - 2375

EP - 2384

JO - Cellulose

JF - Cellulose

IS - 6

ER -