1—A THEORETICAL STUDY OF THE CHANGE OF CURVATURE IN BILATERAL WOOL FIBRES AS A RESULT OF SUPERCONTRACTION

Abstract

The theory developed in this paper to explain the reversal of the curvature occurring in bilateral wool fibres as a result of supercontraction is based on the bimetallic-strip theory. A mathematical formula is deduced that connects the differential contraction with the curvature changes. Experimental measurements of the differential contraction of completely isolated ortho- and paracortical cells in water and after supercontraction treatments show results that are comparable with the theoretical ones calculated by means of the formula.

By comparing the supercontraction of the single cells with that of the whole fibres, it is suggested that, for the merino wool used, the first stage of supercontraction is that of the paracortical component of the fibre, whereas the second stage is due to both components.

KEY WORDS (SPECIFIC TERMS):

• THEORETICAL ANALYSIS
• BICOMPONENT STRUCTURE
• CURVATURE
• FIBRE CRIMP
• SUPERCONTRACTION
• CONTRACTION
• DIFFERENTIAL SHRINKAGE
• BENDING
• ORTHOCORTEX
• PARACORTEX
• MERINO WOOL
• WOOL CELLS
• METHYLENE BLUE

KEY WORDS (BROADER TERMS):

• SHRINKAGE
• MODES OF DEFORMATION
• FINE STRUCTURE (FIBRES)