Intertek tests matrix composite materials for moisture absorption, using ASTM D5229.
Moisture Absorption of Matrix Composites (ASTM D5229) is a gravimetric test method that monitors change over time of moisture content by measuring the total mass change of a coupon that is exposed to a specified environment. Within ASTM D5229 there are three other procedures covering material conditioning within a specific moisture environment.
For Procedure A, at least five 100 mm * 100 mm test specimens are machined from customer supplied product. The side edges are then sealed to prevent moisture absorption through the sides. The specimens are then dried, removed from the drying oven, and allowed to cool in a desiccator. The specimens are then weighed on an analytical balance to the nearest 0.1 mg. The specimens are then placed in the appropriate conditioning environment. The specimens are removed from the conditioning environment periodically, allowed to equilibrate to room temperature in a sealed container, and weighed. This procedure is repeated until there is no discernable increase in specimen weight.
A common size is 100 mm * 100 mm.
Calculated mass change at equilibrium: Mass Change = (Wi – Wb) / Wb * 100