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How Shampoo Influences Human Hair

Dynamic Mechanical Analysis (DMA) measures the visco-elastic properties of mostly polymer materials during a controlled temperature and/or frequency program. During the test, a sinusoidal force (stress σ) is applied to the sample (Input). This results in a sinusoidal deformation (strain ε) (Output).

However, DMA is not only suitable to measure polymer materials. From liquids to highly-filled thermosets to metals and ceramics – all such materials can be measured with the DMA 242 E Artemis. Precise results require optimal adaptation of the test conditions to the materials and applications.

DMA can even be used to study human hair!

Handling hair samples is difficult. However, with the right accessories, DMA allows for studying human hair and evaluating the influence of hair care products like shampoo.

Stress-sweep tests were carried out on a human hair in an air atmosphere and in a mixture of water and shampoo (same hair for both tests). The force was varied from 0.1 N to 1 N and the strain was measured. The plot represents a stress-strain plot for both measurements. The stress-strain plot for both tests shows the difference in the slope of the curves: the hair has higher strain, i.e., it is softer – when in contact with the water-shampoomixture than with air.

Figure 1: Softness of human hair (thickness 70 µm and 80 µm) measured in tension mode at 25°C and a frequency of 1 Hz; force varied between 0.1 and 1 N

DMA can also be used to study the effects of bleaching time, environmental relative humidity and cosmetic treatments on different hair types by determining hair viscoelasticity and storage modulus/stiffness.

The right accessories for every research and quality control task

For the measurement above, the DMA 242 E Artemis was equipped with an immersion bath.

As each material has its own characteristics, NETZSCH has developed a wide range of sample holders, accessories and measurement modes.