Material Library

Aflas® is the trade name (Asahi Glass Co.) for a non-conventional fluoroelastomer (FKM) material which has a different chemical structure than other fluoroelastomers. It is considered a “cousin” of the fluoroelastomers, but offers significant advantages over them.

Aflas® exhibits excellent heat resistance; three months @ 446F, 30 days @ 500F and intermittent tolerance @ +572F. It also offers excellent chemical resistance to high concentrations of acids, alkali and oxidants under high temperatures. In addition, it offers exceptional electrical insulation properties, similar to those of Silicone and EPDM rubber. Aflas® is primarily used for automotive oil sealing components.

Butyl, also known as isobutylene isoprene, has exceptional resistance to gas permeation, along with excellent water and steam resistance. Butyl has a temperature range of -65F to +200F. For most O-Ring applications, Ethylene Propylene (EP) has replaced Butyl due to similar properties, but with better heat and compression set resistance.

Chloroprene (Neoprene®) was one of the first synthetic materials developed as an air-oil resistant substitute for natural rubber. It has the unusual characteristic of being resistant to both petroleum lubricants and oxygen over a temperature range of -40F to +225F. It also provides good resilience and flex resistance.

Hydrin® is a specialty compound, acceptable for use over a temperature range of -40F to + 275F. This compound combines good petroleum oil and fuel resistance, with good resistance to sunlight, ozone and weathering. Hydrin® has good chemical resistance, but may be corrosive to adjacent metal parts. It is frequently used for fuel and oil seals which may be exposed to weather.

EP is a copolymer of ethylene and propylene, while EPDM is a terpolymer combining ethylene, propylene and a diene monomer. EP materials offer a temperature range of -65F to +300F and offer excellent resistance to ozone, weathering, steam, water and phosphate ester type hydraulic fluids. EP can be manufactured to conform to FDA requirements, making it ideal for use with foods and medical devices.

Ethylene Propylene (EPDM) combines a mix of good mechanical properties with excellent ozone, water and UV resistance. Pare these properties with an operating temperature of -65F to +300F and you have an excellent polymer for all weather extremes. Also, its resistance to steam, a broad range of cleaning solutions and FDA compliance makes it a great candidate for food applications.

Fluorocarbon (Viton®) has a temperature range of -20F to +400F, and provides excellent resistance to a wide variety of chemicals, weather and compression set requirements. The relatively high level of fluorine allows for exceptional resistance to chemical attack, but with limited low temperature capabilities. Intermittent exposure to +600F can be tolerated for brief periods of time. Many industrial products are now switching to O-Rings made of VITON®, making it the most significant elastomer development in 50 years.

Fluorosilicone combines the best properties of fluorocarbons and silicones. Fluorosilicone resists solvents, fuel and oil (similar to Viton®), but also provides stability over the broad temperature range of -100F to +350F. This elastomer is frequently used in aircraft fuel systems, however, it is limited to static seal applications due to poor tear resistance.

HNBR, sometimes referred to as highly saturated nitrile (HSN), offers a temperature range of -25F to +350F. HNBR is often used in automotive refrigeration systems using Freon 134A, and in power steering seals using type A fluid. To manufacture HNBR, nitrile is first dissolved in a solvent, then a catalyst is used and hydrogen gas hydrogenates the nitrile. While HNBR is in the nitrile family, it undergoes this extensive, and consequently expensive, process to become HNBR.

Nitrile, also known as Buna-N or NBR, is a copolymer of butadiene and acrylonitirle. It is the most commonly used elastomer for sealing products. It has a temperature range of -40F to +250F and is exceptionally resistant to petroleum base oils and hydrocarbon fuels. Nitrile materials also demonstrates excellent tensile strength and abrasion resistance properties. The material performs well with most dilute acids, silicone oils and lubricants and in water applications. It is not recommended for use with ketones, aromatic hydrocarbons and phosphate ester hydraulic fluids. Ozone resistant nitriles are recommended where extended exposure to air and ozone are anticipated. More than 50% of the O-Rings sold are nitrile O-Rings, commonly used in hydraulic/pneumatic motors, cylinders, pumps and valves.

Perfluoroelastomers combine the chemical resistance of Teflon with the elasticity of Viton® to make a fully fluorinated polymer with superior chemical resistance over traditional elastomers. Saturation by Fluorine along the polymer backbone provides exceptional immunity from chemical attack and temperature range from -25F to +590F. These compounds are usually used in high temperature or caustic chemical applications where traditional elastomers degrade or show reduced product life.

Polyacrylate offers a broad temperature range of -20F to +350F. Often used in automobile transmissions and power steering seals using type A fluid, it has excellent resistance to petroleum fuel and oils. The material also demonstrates good ozone and oxidation resistance, as well as good flex cracking resistance.

Polyurethane compounds offer exceptional abrasion and wear resistance and are offered in two distinctively different variations. For use in oil, use a polyester type that has low volume swell, but softens dramatically when exposed to water. For water sealing applications, use the polyether type, which retains its integrity in water, but swells significantly when exposed to oil. A hybrid version that is acceptable for both applications is available at a substantially higher cost.

Polytetrafluoroethylene is a completely fluorinated polymer that is the most chemically resistant polymer available. PTFE can withstand a very wide temperature range from -300F to +500F. It is inert to most chemicals and solvents with very few substances that degrade the material (notably fluorine, chlorine trifluoride and molten alkali metal solutions) PTFE is also very slippery and repels virtually everything making it perfect for applications that require a high coefficient of friction. PTFE is not crossed-linked like a regular elastomer and therefore has poor elastic memory, can deform under constant compressive load and can be damaged during installation.

Silicone materials offer outstanding temperature resistance across a broad range, from -80F to +400F. Silicone materials provide excellent resistance to sunlight, ozone, oxygen, UV light and moisture. Its inert qualities make it the preferred material for use with food handling and medical applications. Silicone offers poor tensile, tear and abrasion resistance, and as a result the material is not recommended for use in dynamic applications with friction.

SBR, styrene butadiene, or Buna-S, was originally developed to replace natural rubber in tires. While sometimes used for automobile brake system seals, it has been replaced in most applications by ethylene propylene, which offers superior heat and compression set resistance.

UltraSlip® is Boyds’ proprietary internal-lubricant available for many compounds including nitrile (Buna-N) and ethylene propylene (EP or EPDM). The material was developed for use in applications where incredibly low breakout friction and low running friction are required. This specially formulated internal-lubricant provides the lowest coefficient of friction for any O-Ring when compared to compounds filled with Teflon®, moly-disulfide, silicone or wax. The lubricant also conforms to FDA CFR 177.2600 standards.