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.