Britannica Sources used in this answer

Why are ethylene-propylene elastomers weakened by hydrocarbon oils?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Know how researchers created a synthetic material, elastomers, that can change color and texture to specific voltage change, like that of cephalopods — elastomer Learn about elastomers that are changeable in colour and texture, much like the skin of octopuses and other cephalopods. In the elastomers, these changes take place under electrical stimulation.

Ethylene-propylene elastomers, such as EPM and EPDM, are classified as hydrocarbon elastomers. Like other materials in this category, they are susceptible to being swollen and weakened when exposed to hydrocarbon oils.12

This occurs because of the chemical similarity between the elastomer and the oil. Because both the ethylene-propylene copolymer and the hydrocarbon oil are nonpolar, they are chemically compatible, which allows the oil to penetrate and diffuse into the polymer matrix. This absorption causes the material to swell, which disrupts the intermolecular forces holding the polymer chains together, ultimately leading to a loss of structural integrity and mechanical strength.12

Due to this poor resistance to oil, ethylene-propylene copolymers are generally not suitable for applications involving direct contact with hydrocarbon-based fuels or lubricants.3