The UV radiation component of sunlight is very harsh on polymers. Heat caused by the infra red component will degrade and even physically distort a product. Combined with rain and humidity, a chemical change (oxidation) or breakdown can occur. This then leads to lower strength, loss of color (fading), distortion and corrosion.
The effects of sunlight on the atmosphere in conjunction with emissions from man and his industries results in everything from acid corrosion to ozone breakdown of materials and products.
Tests that fall under such exposures include:
QUV & UVCon ASTM G53, G154 SAE 2020
Weatherometer – Xenon C135, ASTM G15, G26 SAE T885
UV @ 264mm – Automotive / Electronics spec
Mil Spec 810 E,F,G Procedures I & II
Indoor Fluorescent exposures
Photodegradation evaluates UV breakdown of polymers and composites. Tensile tests, infrared monitoring of the materials and weight loss are included. A total of 15 days accelerated UV exposure is performed.
Exposing materials or products to ozone tests their resistance to such an aggressive atmospheric chemical. Elastomers have to resist ozone or else they become embrittled prematurely and fail.
Pollutants found in industrial areas and some natural sources include sulfur dioxide, hydrogen sulfide and ozone. Combined with carbon dioxide and water these pollutants are highly corrosive. Exposure testing of gases is necessary for many materials and product applications.
High humidity, as well as the cycling between high and low humidity will effect the performance of most materials. The proper balance and effect of humidity is important. Some plastics will not process or mold properly with high moisture content, but can gain strength after molding when moisture is added.
Thermal cycling goes from hot to very cold back to hot. This type of testing accelerates product and material failures under extreme conditions of environmental use. Very rapid cooling or heating can be used to induce Thermal Shock, a variant of normal thermal cycling.
Evaluates the heat degradation of materials. Physical, chemical and visual evaluations are included in these tests.