Coefficient of Moisture Expansion (CME)

Molecular Weight Determination of Oils

The Coefficient of Moisture Expansion is used to determine the stability needed for the aircraft components. It is also defined as the ratio of length to mass variation by moisture absorption or evaporation. It is denoted by,

where m₀ and l₀ are initial mass, and initial length and Δm and Δl are mass and length variation. The CME values of carbon fibre-reinforced polymers range from about 1×10^-3 /wt% H₂O average to the fibers to about 5 x 10-5 / wt% H₂O in the direction of the fibers. Two laser micro-interferometers, one focused on the front and one on the back of the sample, measure the length variation. The most significant possible selection is 300mm by 30mm. The anticipated CME values of advanced composites can be calculated regardless of the available space. The system is installed on a single support frame and operated in a vacuum (10^-3 Pa). 

Video 01: Coefficient of thermal expansion

Common Uses of Coefficient of Moisture Expansion (CME)

• It is used to design high-stability structural applications. 
• It is used to determine the corrosion rate of metals, thus helping in building predictive models. 

Advantages of Coefficient of Moisture Expansion (CME)

• Evaluates the materials of aerospace applications by CME.
• Helps in the construction of high-stability structural applications.

Limitations of Coefficient of Moisture Expansion (CME)

• The aligned composite has a low and decreasing moisture expansion coefficient, depending on the amount of fiber.
• A high-resolution and precision measurement method is necessary due to the low values in the 0° direction.

Industrial Applications of Coefficient of Moisture Expansion (CME)

• Aerospace
• Aeronautic
• Polymers
• Nuclear Reactors