Compatibility assessment of modern elastomers with grease

In many technical applications, elastomers are used as sealing materials or supply hose. These elements are exposed to aggressive factors that have a devastating effect on their structure. Due to their construction, elastomers deteriorate over time and with temperature increase, exposure to ultraviolet light, ozone and various organic substances. One of the requirements for lubricants is compatibility with the elastomeric material. Currently, the requirements for elastomers are becoming stricter, which is mainly related to environmental protection (elimination of all leaks) and extending the period of failure-free operation of devices. However, the working conditions of the seals are becoming more and more difficult, especially due to the introduction of synthetic oils and the increase in the working temperature. These changes make it necessary to introduce rigorous testing of elastomers, including compatibility with liquids. Seals are the least durable of the elements of lubrication systems / friction nodes. The elastomers they are made of can age in a relatively short time under adverse conditions, radically changing their physical properties. They begin to swell visibly, their hardness and strength change. The risk of unsealing the system in the event of incompatibility of lubricants with seals can generate significant financial losses. Because operational and bench tests are long-term and very expensive, and moreover not very objective, laboratory tests are used to check compatibility. Samples of a given elastomeric product are used and exposed to the test lubricant for a specified time at a specified temperature using standardised test methods. The article describes the interaction between elastomers and grease. Based on a literature review and observations made during the tests, preliminary acceptable limits for changes in physical and mechanical properties were defined to assess the resistance of elastomers to the impact of grease.