Relative Humidity Induced
Glass Transition Temperature
The effect of relative humidity on the glass transition temperature for amorphous compounds has a significant influence on the material’s physicochemical properties. Water acts as a plasticizer for many amorphous compounds, and the property changes initiated by a phase change can have a critical impact on the stability, performance, and shelf life of a product.
The presence of amorphous materials in pharmaceutical products causes large challenges in the processing, storage, and delivery because they have different properties from their crystalline counterparts. When formulating amorphous powders, it is integral to understand the critical stability regions. They have a great impact on the final formulation performance, predicting if a moisture-induced phase transition occurs. They have a great impact on the final formulation performance, predicting if a moisture-induced phase transition occurs. Water can act as a plasticizer, which may reduce the glass transition temperature significantly, resulting in spontaneous phase transitions. With the potential for these meta-stable states to convert to crystalline states, there must be a thorough understanding of the temperatures and relative humidity of the glass transition temperature from amorphous to crystalline regions. This can be mapped out conveniently with DVS and IGC experiments.
DVS Application Note 35: Determining the Moisture-Induced Glass Transition in an Amorphous Pharmaceutical Material | Request a copy
The glass transition temperature (Tg) is an important property in food characterization. Polymers and natural macromolecules such as maltose exhibit Tg, which may affect the stability and physiochemistry of food powders and formulations. Infinite dilution in the iGC-SEA can quickly record second-order phase transition effects for materials such as maltose at a different relative humidity, to determine the glass transition temperature for these products. In this application note, the Tg of maltose is measured using Inverse Gas Chromatography.
iGC SEA Application Note 204: Determination of the glass transition temperatures, Tg, of Maltose and its dependence on relative humidity by infinite dilution inverse gas chromatography (iGC-SEA) | Request a copy
The glass transition temperature is a critical property of amorphous polymers dictating their behavior and uses as a material. The glass transition temperature (Tg) of a polymer relies heavily on humidity, with water acting as a plasticizing agent to reduce the Tg of a polymer. It is critical to understand the stable regions of a polymer, to optimize its function and durability. iGC-SEA is used as a sensitive measure of Tg for a polymer, alongside DVS in humidity ramping experiments.
iGC SEA Application Note 303: An overview of iGC SEA – a new instrument for characterizing the physico-chemical properties of polymers | Request a copy
Studying relative humidity & glass transition temperature in your research
With various instruments suited to determine relative humidity and glass transition temperature, find out which one is right for your lab using the link below.