Vapour transport characteristics of materials play an important role in many industries. Considering that hydration and solvation are a major factor in the activity and application of bio-based materials, the water or organic vapour sorption isotherms would provide fundamental information on the mechanism of the hydration or solvation. Other properties such as moisture vapor transmission rate (MVTR) may be studied under isothermal conditions to investigate the rate of vapour permeating through a biopolymer membrane.
The amount of surface area that a solid contains greatly influences the number of vapour molecules it may adsorb. Therefore, the surface area has huge implications for the solid’s physical properties and ideally would be measured at atmospheric conditions. The advantage of the Dynamic Vapour Sorption (DVS) technique over the traditional nitrogen sorption technique is that the surface area measurement can be performed at atmospheric conditions rather than at liquid nitrogen temperature.
Knowledge of the hygroscopic properties of bio-based materials can be transferred to other fields of applications. Wheat straw, for example, is a source of bio-fuel. At 95% RH, the pre-treated sample has a mass uptake of 59.62%, and the raw sample, 24.76%. This indicates an open-up of more accessible sites to water molecules, which will be beneficial to subsequent hydrolysis process.  Peng Miao, Majid Naderi, Manaswini Acharya, Jiyi Khoo, Dan Burnett and Daryl Williams. Characterisation of Wheat Straw Using Dynamic Vapour Sorption Method. Proceedings of the 55th International Convention of Society of Wood Science and Technology August 27-31, 2012 – Beijing, CHINA.