Testing of coatings, sealants and elastomers often involves exposure of the material to conditions that simulate the intended use environment. For products intended to last years or decades, it is convenient to accelerate aging tests by intensifying the environmental conditions. Numerous test methods have become standardized and widely used for the purpose of evaluating resistance to environmental aging. Presented here are some of the accelerated environmental exposure tests that can be conducted at August Research Systems (ARS).
Accelerated Weathering (Xenon-arc)
This test is an accelerated evaluation of material degradation through exposure to light, heat and moisture which is representative of long term outdoor exposure. The xenon-arc lamp produces a radiation profile that closely simulates natural sunlight. Moisture exposure is possible through a controllable humidifier and water sprayer. This test conforms to ASTM G154.
Autoclave (Hydrolytic Stability)
The autoclave subjects materials to elevated heat, pressure and saturated steam, simulating long term exposure to hot and humid environments. Under these conditions some elastomeric materials are susceptible to hydrolytic degradation.
Humid Aging
Similar to the autoclave, but nowhere near as extreme, the humidity chamber exposes materials to relative humidity conditions between 30 and 95% at temperatures up to 155°F.
Salt Spray (Fog) Apparatus
The salt spray test is an accelerated evaluation of the corrosion resistance that a protective coating provides to a metallic substrate. An aqueous salt solution is sprayed onto the test specimen, and after a predetermined duration the degree of corrosion is determined. This test conforms to ASTM B117.
Temperature Cycling
To evaluate materials that will be subject to cyclic temperature variations, such as aircraft coatings, which might endure –60 to 280°F temperature swings regularly, ARS utilizes freezers and ovens to periodically expose samples to extreme temperatures. This test typically involves subsequent property change evaluations, such as hardness, color, tensile strength or flexibility.
Fluid Immersions
Material properties can change when exposed to fluids that may be encountered in use. ARS conducts a variety of tests that evaluate the properties of a material after it has been immersed in fluids such as solvents, oils, fuels, or cleaning solutions, just to name a few. Mass and volume swell determinations are common fluid resistance tests.
