Differential Scanning Calorimetry
TA Instruments DSC25 and DSC2500
The Differential Scanning Calorimetry (DSC) TA Instruments DSC 25 and DSC2500 are used to characterize the phase transitions that occur in materials as they are heated. The DSC2500 has a modulation option. Modulated DSC determines the total, as well two individual heat flow components (heat capacity component and kinetic component), to provide increased understanding of complex transitions in materials.
A popular application of DSC is the characterization of hair damage, where the keratin denaturation transition is used assess the structural integrity of hair proteins. Changes in the denaturation temperature and enthalpy can be associated with particular changes in the hair cortex. TRI has performed DSC studies on the effects of different damage treatments on hair proteins, including heat styling damage, UV (sunlight) damage, pollutant gas (e.g. ozone) damage and hair bleaching damage.
DSC is not just limited to hair applications, and can be used to evaluate stratum corneum lipid and protein structures, and the physical properties of cosmetic products (e.g. creams, lipsticks, styling products etc).
Keratin denaturation endotherms observed in a wet-DSC experiment on undamaged human hair. This example shows the effects of heating rate on peak size and position.
Malinauskyte, E. (2019) https://library.triprinceton.org/1cts0dg/
Malinauskyte, E. (2021) https://library.triprinceton.org/1jllmsk/