Overview of Elastomers & Elastomer Materials

Elastomers, both natural and synthetic, have common characteristics including elastic recovery after stress, flexibility, extrusion resistance, and relative impermeability to gases and liquids. Each class of elastomer has its own unique properties and performance that can be modified by the inclusion of other ingredients. There are over 20 classes of elastomers. The elastomers listed are frequently used in applications that require fluid handling. Information regarding these elastomers was supplied by industry sources, including the Fluid Sealing Association. Trademarked products are manufactured by Qnity. For more specific information about these polymers, including data sheets, refer to the section titled: Elastomer Products from Qnity.

Elastomers are formulated by compounders to afford specific engineering properties for an application. Vulcanization converts the thermoplastic compound into the desired thermoset shape. Crosslinks among the polymer chains impart strength and elasticity to the sealing product. It is important for seal specifiers to consult with the seal manufacturer to determine the appropriateness of particular materials for an application.

Elastomers versus plastics -
Elastomers are long-chain polymers connected by crosslinks that impart strength, resilience and elasticity, and these crosslinks are very stable to heat and high pressure.

Plastics are also long-chain polymers, but they are not connected by chemical crosslinks. Plastics acquire their strength when the chains orient with one another and become crystalline in regions. These regions may deform or melt under high pressure and temperature.

Compared to plastics, elastomers provide:

• Very good dimensional stability over a broad temperature range
• High compression set resistance
• Excellent extrusion resistance at high temperatures and pressures; and
• Retention of sealing force during pressure and temperature cycling (a major problem with many plastics)

Elastomers Characteristics