Thermogravimetric analysis for rapid assessment of moisture diffusivity in polydisperse powder and thin film matrices

- Thermogravimetric approach was employed to determine moisture diffusivity.
- The approach is tailored for thin film and polydisperse powder samples.
- The approach is capable to measure diffusivity at elevated temperatures (>70 °C)
- Measured diffusivity data show good agreement with available literatures.
- This study improves our understanding on temperature-dependency of diffusivity.

Accurate description of moisture diffusivity is key to precisely understand and predict moisture transfer behaviour in a matrix. Unfortunately, measuring moisture diffusivity is not trivial, especially at low moisture values and/or elevated temperatures. This paper presents a novel experimental procedure to accurately measure moisture diffusivity based on thermogravimetric approach. The procedure is capable to measure diffusivity even at elevated temperatures (>70 °C) and low moisture values (>1%). Diffusivity was extracted from experimental data based on “regular regime approach”. The approach was tailored to determine diffusivity from thin film and from poly-dispersed powdered samples. Subsequently, measured diffusivity was validated by comparing to available literature data, showing good agreement. Ability of this approach to accurately measure diffusivity at a wider range of temperatures provides better insight on temperature dependency of diffusivity. Thus, this approach can be crucial to ensure good accuracy of moisture transfer description/prediction especially when involving elevated temperatures.