A discussion about UV-resistant materials needs to start by defining what UV is and how it can affect rubber materials. Ultraviolet (UV) rays most commonly emanate from the sun, but they can also be produced by some lamps and lasers.
Rubber materials can be adversely affected by ongoing exposure to UV radiation, as it affects the molecular structure of the material which causes it to break down or degrade. Both physical and chemical changes can occur in natural and synthetic polymers such as some rubbers, causing it to crack, lose flexibility, weaken, fade and ultimately, even disintegrate.
The extent of possible degradation due to UV exposure depends on whether the part is going to be partially or constantly exposed to the sun. UV-resistant materials are not usually needed for indoor applications.
Some materials break down fairly quickly once exposed to UV, including natural rubber (NR), Styrene-Butadiene (SBR), and Nitrile Rubber (NBR, Buna-N). NR rubber suffers from poor resistance to hydrocarbon oil, while SBR has poor resistance to oil. Both materials are not suitable in weathering, UV, oxygen, ozone applications, because of the double bond in the polymer backbone. Nitrile rubber compounds are susceptive to ozone, ketones, ethers, esters, aromatic hydrocarbons, automotive brake fluid, strong acids, and aldehydes.
EDPM and silicone are well-known for their UV-resistant qualities. Silicone has excellent heat and ozone resistance, high dielectric stability and resistance to many oils, chemicals, and solvents.
EDPM possesses excellent resistance to ozone, sunlight, and weathering. It also has very good flexibility at low temperatures, has good chemical resistance, and good electrical insulation properties.
If your application is going to be constantly exposed to the sun, make sure you select a UV-resistant rubber material to ensure it doesn’t deteriorate or even disintegrate.
Interested in learning more? Speak to us about your application.