Ozone Resistance Testing (ASTM D1149)

Rubbers are often exposed to elements, one element that can affect the performance of rubbers over time is ozone. Ozone primarily affects rubbers with unsaturated carbon-carbon double bonds in the chemical structure through an ozonolysis reaction. The most common rubbers that have these bonds and are prone to ozone degradation include: natural rubber, polybutadiene, nitrile (NBR), SBR, and polyisoprene. These rubbers are very commonly used and are often needed in certain applications either for their high strength, oil resistance and other unique properties that these rubber polymers have. With that being said, if these rubbers are placed in conditions that originally they perform well in if not protected these rubbers can degrade over type causing the rubber to crack and no longer perform as intended in the application. Luckily there are additives, and options when creating these compounds to provide resistance to ozone degradation. We perform tests in our lab to be able to test to ozone resistance requirements for our customers and for internal requirements depending on the application of the rubber compound.

The most common standard that we use is ASTM1149, but we are also able to perform the test to these additional specifications depending on customer requirements: JIS K 6259 ASTM1171 ISO1431 DIN53509 GB7762 GB/T13642. There are several variations of the tests to measure the level of deterioration of rubber compounds to ozone but in principal cured molded specimens are placed in a chamber at a specific temperature, ozone level concentration, and for a specific amount of time. Inspection is done on the surface of these specimens to examine for signs of degradation. Based on these inspections a score is given to the rubber specimens specifying the level of resistance to ozone of that material.

Some additives used to provide ozone resistance can cause other problems including staining and blooming where chemicals arise to the surface of the rubber part. For matting or applications where rubber comes into contact with other materials it is often important to avoid staining, and blooming can often make the rubber part change its color affecting the cosmetics. For this reason it is important to understand the side affects of different additives at different concentrations to avoid any surprises. Rubber Mexico has ample experience with developing rubber compounds to meet customer requirements while also meeting the overall expectation of the rubber part in the end application. Reach out to Rubber Mexico for all your rubber needs where your part needs to perform without degradation from ozone and environmental exposure!