Dilatometry: measuring the thermal expansion and transitions of your materials
Dilatometry is a thermal analysis technique used to measure the dimensional changes of a material as a function of temperature. It allows the determination of key physical properties such as the coefficient of linear thermal expansion (CTE) , the glass transition temperature (Tg) melting and deformation points . Widely used in the materials, plastics, packaging, aerospace, and medical industries, dilatometry is an essential tool for predicting thermomechanical behavior under real-world conditions.
What is dilatometry?
Dilatometry involves precisely measuring the dimensional changes of a sample when subjected to an increase or decrease in temperature . These variations, linked to the thermal agitation of atoms, allow the thermomechanical behavior of the material to be determined.
Depending on the type of analysis, dilatometry can be:
- Linear : variation in length depending on temperature
- Volumetric : variation in volume, for certain specific materials
- Comparative or absolute , depending on whether or not a standard is available.
Dilatometry is generally performed using a thermomechanical analyzer (TMA) in dilatometric mode.
How dilatometry works
The sample is subjected to a controlled thermal program (heating or cooling) and placed between two sensors, one of which measures the change in size.
Experimental conditions may include:
- Temperature ranges : typically from -150 °C to +1600 °C depending on the instrument
- Analysis medium : air, inert gas (nitrogen, argon)
- Applied load : low, constant or variable (analysis in free expansion or stress)
- Heating speed : adjustable to reveal thermal transitions
The results are presented as expansion curves and allow for the calculation of:
- The coefficient of linear thermal expansion (CTE)
- The glass transition temperature (Tg)
- The softening or melting
- The phenomena of shrinkage , cracking or structural changes
Technical characteristics of dilatometry
- Dimensional resolution : up to 0.1 µm
- Extended temperature range : from -150 °C to +1600 °C
- Atmosphere control : air, nitrogen, argon, vacuum
- Non-destructive method
- Various samples : bars, films, lozenges, agglomerated powders
- Applicable standards : ISO 11359, ASTM E831, ISO 20340, ICH Q2(R1)
For which matrices?
Dilatometry is suitable for many types of materials, particularly those whose performance depends on their dimensional stability over temperature :
Main industrial applications
Dilatometry is used in research and development , quality control , product expertise , and materials validation in various sectors. For example:
Léa Géréec
Technical and scientific advisor
