Vapor Sorption / Dynamic Vapor Sorption
Vapor Sorption: The moisture content of materials used in pharmaceuticals, foods, personal care products, nutraceuticals, and medical devices is important as the moisture content influences the properties (mechanical and chemical) and stability of these materials. Vapor sorption isotherms can be used to detect hydrate and solvate formation. Cameras installed in the equipment can be used to detect irreversible changes or deliquescence. Isotherms and package permeabilities can be used to determine product shelf life for hygroscopic materials. Capsule mechanical properties depend on moisture content. Isotherms can be used to choose the proper humidity range.
DVS: Dynamic Vapor Sorption uses a programmed stepwise change in humidity or solvent vapor pressure to determine the sorption isotherm. After each step and after a suitable equilibration time, the mass of the sample is recorded. DVS is a rapid method for determining sorption isotherms and is considered to be a valuable tool in many research laboratories throughout the world. This technique offers the ability to measure vapor sorption isotherms from 25 °C to 40 °C. DVS measurements can be important when making packaging decisions.
VVS: Volumetric Vapor Sorption produces data similar in format and utility to that provided by DVS. Instead of using a micro balance to determine the amount of vapor sorption, the VVS technique uses pressure measurement to determine the volume of vapor that is either adsorbed or absorbed. This technique allows for the determination of high resolution isotherms that can pinpoint the onset of material changes at a specific relative humidity. For porous materials, the technique allows for pore size distribution measurements using vapor as an adsorptive.
DVS Application Note 52:
Vapour Permeability of Porous Materials using Payne Diffusion Cell
Overview: Vapour permeability in porous materials is of interest to a variety of different industrial sectors including packaging materials, membrane technologies, tissue engineering scaffolds etc. This application note describes the measurement of moisture vapour transmission rates (MVTR) through porous materials (i.e. silicone membranes/human skin and electrospun polymer fibre mats), using a Payne type diffusion cell and DVS instrument.