The merino fibre is highly extensible, a characteristic that increases as it absorbs water. (Fig 1)
When wet, a merino fibre can be extended up to 30% without damage and when the force is removed the fibre will recover its original dimensions completely. If a merino fibre or garment is stretched while dry, steaming or wetting with water can be used to speed up the rate of recovery.
Merino’s extensibility is due to the ability of the fibre to undergo a reversible change from a helix to a sheet formation as it is elongated. The helices progressively unfold when the fibre is stretched between 2 and 30%, and the process is known as alpha to beta transition. (Fig 2)
The merino fibre can transform from a helix to a sheet formation upon elongation, giving it high extensibility that increases with moisture content.
All figures and tables courtesy of CSIRO unless otherwise noted.
