- Occlusion
- The mechanical entrapment of gases, liquids or solids within the folds of a substance.
- O.D.
- The outside diameter of an o-ring. A dimensional reference.
- Off Register
- Eccentric o-ring cross-sectional radii caused by lateral shift of one mold cavity relative to the other.
- Oil Resistant
- Ability of vulcanized rubber to resist swelling and other detrimental effects of exposure to various oils.
- O-Ring
- A doughnut-shaped object, or torus, that functions as a seal, blocking the passage of liquids or gases, by being compressed between the two mating surfaces comprising the walls of the cavity (gland) into which the ring is installed.
- Oscillating Seal
- Most commonly used in faucet valves, in this application the inner or outer member of the gland moves in an arc around the axis of a shaft. Movement is limited to a few turns in one direction and a few turns in the return direction (i.e. faucet on, faucet off).
- Outgassing
- Primarily occurring in vacuum situations, the volatile (evaporative) components of some rubber compounds may become vaporized in the vacuum and released (outgassed) by the compound into the surrounding environment.
- Oxidation
- The reaction of oxygen with a rubber compound, typically resulting in surface cracking of the rubber material. As oxidation involves the transfer of electrons, reduction in the physical strength of elastomers may also occur from exposure to the oxidizing agent.
- Ozone Resistance
- The ability of vulcanized rubber to withstand cracking and physical deterioration from exposure to ozone, a more active oxidizing agent than oxygen itself.