One of the chief disadvantages of wood in use
is its inability to retain its shape with the change in
the moisture content. It shrinks and swells as water is
desorbed or adsorbed in the cell wall of the wood fibre
which is composed primarily of cellulose ‘mnicrofibrils.
The hydroxyl groups—of—the e. e ll.ulose c.hain-exhibi^t—strong…-
affinity for water molecules* The hygroscopisity of wood
— is due to–these–water loving hydroxyl groups. In the swollen
state water is adsorbed to the easily ■ accessible–hydroxyl- — –
groups of the less^ordered..amorphous–region^–With-the loss
of water, on.Jurying 3 surface tension forces pull the adjacent
cej, ] nInsebchains together causing shrinkage of the fibres
equal to the volume of water removed.