Poster: How Heat Spreads through Human Hair: Measuring the Thermal Diffusivity Across Hair Types

Event Date: June 8, 2017
Authors: J. Hahn, T. Reid, and A. Marconnet
Journal: TRI Hair Measurement Science Symposium
TRI Hair Measurement Science Symposium, Princeton, NJ, 2017.

While heat damage caused by grooming practices such as flat ironing is one of the major concerns for consumers, little is known about how heat spreads through human hair. A measurement technique based on the Angstrom's method was developed to measure thermal diffusivity of hair. Thermal diffusivity is a parameter that combines specific heat capacity, density and thermal conductivity of materials; it indicates how effectively heat spreads throughout the material. With the measurement of specific heat capacity and density, one can derive thermal conductivity, which describes the rate of heat energy transported within materials. Measurement of polymer materials with well known thermal properties indicates high accuracy and reliability of the measurement technique. The measured thermal diffusivity of human hair ranged from 0.24 mm2/s to 0.57 mm2/s at differing levels of frequency. This work will lay the foundation for follow-up work involving heat transfer modeling ofhair bundles with flat irons as a heat source.