Indian researchers have been investigating the nano-tensile properties of human hair using an Lfplus single-column materials testing machine and Nexygenplus analysis software from Lloyd Instruments.
Using a specially designed winding grip to secure the sample, individual hairs undergo 'pull-to-break' tests to determine Young's modulus, yield stress and tensile strength.
Human hair has an outer layer of flat scales known as the cuticle, which protects the softer inner cortex tissue.
As the hair is stretched, small stress drops are seen on the tensile curves before the fibre fails completely.
These initial stress drops are due to strands of the cuticle failing while the cortex remains intact.
The system is being used to analyse the differences in nano-tensile mechanical properties between different types of hair.
Lloyd Instruments' universal testing machines have also been used elsewhere to evaluate the physical and mechanical properties of synthetic fibres used in wigs, both for research and development and production quality control.
Tests can be carried out on individual fibres or bundles of fibres and include measuring maximum load, extension at maximum load, and extension at half load.
The force data can then be compared with the filament 'denier' weight to achieve a final result in gf/denier.
