ASTM D5229 Standard Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials

Get Certified ASTM D5229 Testing for Reliable Moisture Absorption Evaluation

ASTM D5229 tests are used to measure moisture absorption, moisture desorption, moisture diffusivity, equilibrium moisture content, and moisture conditioning of polymer matrix composite materials. The results can then be used by manufacturers, engineers, researchers, and quality-assurance staff to assess the environmental impact and to prepare specimens for subsequent mechanical or other material property testing. Tests are performed by placing representative composite coupons in a controlled temperature and moisture environment and measuring the mass change of the composite coupons according to the applicable requirements of ASTM D5229. The data can also be used to help moisture prediction analysis and decisions on the performance of materials when exposed to the environment.

• Material: Polymer matrix composite materials and other suitable Fickian solid materials.
• Moisture absorption: Determination of moisture uptake through the specimen thickness.
• Moisture desorption: Determination of moisture loss from conditioned materials.
• Procedure A: Determination of moisture diffusion properties and moisture equilibrium content.
• Conditioning: Preparation of coupons to specified environmental or equilibrium conditions.
• Moisture-free condition: Conditioning to an essentially moisture-free state before subsequent testing.
• Moisture loss: Evaluation of moisture loss during elevated-temperature testing or after removal from a conditioning environment.
• Diffusion model: Evaluation of through-the-thickness moisture diffusivity for materials meeting single-phase Fickian assumptions.
• Environmental exposure: Conditioning under specified temperature and moisture exposure levels.
• Data reduction: Calculation of moisture content, moisture diffusivity, equilibrium moisture content, and related conditioning information.

What are the Uses of ASTM D5229 Testing?

ASTM D5229 provides procedures for testing the moisture absorption characteristics and for establishing controlled moisture conditions for polymer matrix composite materials. The results can then be used by manufacturers, engineers, researchers, and quality-assurance staff to assess materials or set up materials for further testing. The ASTM D5229 standard-

• Measures the moisture absorption and desorption characteristics along the thickness of the specimen.
• Evaluates through-the-thickness moisture diffusivity constant for appropriate single-phase Fickian materials.
• Calculates the moisture equilibrium content under given environmental conditions.
• Sets approximate exposure times for conditioning coupons to equilibrium.
• Exposes specimens to specified environmental exposure levels prior to other material property testing.
• Dries out specimens to a virtually moisture-free state when necessary.
• Measures the amount of moisture that is lost from conditioning environments.
• Measures moisture loss in tests at high temperatures.
• Provides information for moisture prediction analysis and environmental performance evaluation.
• Assists with material selection and evaluation of polymer matrix composite performance when exposed to moisture.

Which materials can be tested under ASTM D5229?

ASTM D5229 applies to laminated polymer matrix composite materials or other solid materials that meet the assumptions for the procedure selected. The method is mainly designed for composite materials in flat or curved panel form in which moisture movement through the thickness can be assessed. For the most part, reinforced polymer matrix composites tested at temperatures lower than the glass-transition temperature of the polymer matrix are likely to meet the single-phase Fickian assumption, but materials with two-phase matrices or complex moisture transport behavior may require further consideration. The procedures themselves may be applied to materials having more complex behavior, but the moisture diffusivity calculations of Procedure A are valid only when the necessary single-phase Fickian assumptions are met.

Why is ASTM D5229 Important?

ASTM D5229 is important because it provides a standardized method for measuring the moisture absorption characteristics and preconditioning of polymer matrix composite materials. The moisture diffusion material property data obtained in Procedure A can be used to estimate the conditioning times and in moisture prediction analysis, and Procedures B through E set specified environmental or equilibrium conditions. Procedures Y and Z are related to the moisture loss that occurs when specimens are taken from conditioning environments or tested at elevated temperatures. The method also acknowledges the fact that exposure to moisture in vapor can be different from exposure to liquid, and apparent absorption properties from liquid exposure should be noted as such. These requirements give consistent information for environmental conditioning and evaluation of composite material.

ASTM D5229 Testing Process and Data Collection

ASTM D5229 requires the weighing of prepared composite coupons and the exposure in controlled environmental conditions with observation of the change in mass of the specimens by technicians. In moisture absorption testing, the initial mass and the mass after a set period are measured, and the moisture content is calculated. When the single-phase Fickian assumptions are valid, Procedure A can be used to calculate moisture diffusivity and equilibrium moisture content from the resulting absorption history. Procedures B through E set specific conditioning conditions, and Procedures Y and Z measure moisture loss due to removal of specimens or due to testing at elevated temperatures. The measurements collected are then used to record moisture conditioning, to determine the moisture properties of the materials, and to be used in subsequent environmental or mechanical property evaluations

Common Challenges and Troubleshooting

The problems associated with ASTM D5229 are related to inadequate specimen geometry, inaccurate mass measurements, uncontrolled temperature or humidity, edge effects, incomplete moisture equilibrium, and non-Fickian moisture behavior. Therefore, the technicians should examine the dimensions, surface condition, balance accuracy, environmental stability, and weighing interval of the specimens prior to testing. When through-thickness diffusion is to be determined, the geometry of the specimen should be arranged to minimize moisture transport through the edges. Analysts should also ensure that the environmental exposure is constant during conditioning and that the specimens are weighed promptly enough to minimize moisture loss during handling. When the absorption curve does not show the behavior necessary to use the Fickian calculation, engineers should consider whether it is applicable to the curve before reporting a moisture diffusivity constant.

• The laboratory reports the moisture content of the composite specimens at the required exposure times.
• The analyst reviews the mass-change history to evaluate moisture absorption or desorption behavior.
• The laboratory determines the moisture equilibrium content for the given environmental condition.
• Engineers determine the through-the-thickness moisture diffusivity constant when Procedure A assumptions are satisfied.
• The absorption curve is checked for a suitable initial linear region, and then the Fickian diffusion calculation is applied.
• The laboratory verifies dimensions, thickness, mass measurements, conditioning temperature, and moisture exposure level of the specimens.
• Engineers consider moisture loss due to the removal of specimens from conditioning or elevated-temperature testing, when applicable by Procedures Y or Z.
• Analysts distinguish vapor-exposure results from apparent absorption properties obtained through liquid immersion.
• The results are used by engineers for environmental conditioning, moisture prediction, material selection, and composite-performance evaluation.

Link to ASTM D5229