What is Fuel Resistant Epoxy & What are Its Applications?

Contact with fuel negatively affects most plastic resins due to the corrosive nature and heat associated with burning fuel. Resistant epoxy properties extend to chemicals as well as fuels, making the material very suitable for such applications, in contrast to thermoplastic-based resins like silicone that tend to fail when in contact with fuel. In fact, these innate traits in fuel resistant epoxy make it far more resilient, particularly when used within epoxy-based composites. With epoxy, properties inherent to the resin like chemical resistance, durability and structural integrity also help make composites more fuel resistant. Epoxy-based composites are key in the construction of aerospace fuel systems, components for fuel systems, fuel tanks, gaskets, sealing joints, and a range of industrial equipment.

What is Fuel Resistant Epoxy? 

Often used as a coating or specialized adhesive within composite materials, fuel resistant epoxy can endure exposure not only to fuels, but also to various types of oil and harsh chemicals. Epoxy properties like resistance to chemical-induced corrosion make it more durable, which is why it’s often used in marine, automotive, aerospace, and other industries. Fuel resistant epoxy used as an adhesive is used primarily to create a bond between two surfaces, though it is also utilized for coating, sealing, or otherwise enclosing certain component features. Epoxy properties make it a good choice for items regularly exposed to diesel fuel, gasoline, jet fuel, and various other fuel types.

Key epoxy properties that help them resist contact with fuel include: 

• Adhesion strength: Able to bond to composite, metal, polymer, and other surfaces, fuel-resistant epoxy forms a barrier that prevents fuel from leaking and components from degrading due to contact with it.
• Chemical inertness: This epoxy property ensures composites won’t react to chemicals by weakening or breaking down over time. 
• High cross-link density: When cured, epoxy forms into a solid construction that keeps fuel from penetrating and degrading components.
• Hydrocarbon resistance: Epoxy’s ability to resist solvents also makes it resistant to aliphatic and aromatic hydrocarbons within fuels, preventing components from dissolving or eroding.
• Low permeability: With its dense molecular structure, epoxy cannot be easily absorbed and does not soften or swell when exposed to fuel made from hydrocarbons.
• Oxidation resistance: While fuel exposure can cause certain polymers to degrade over time, epoxy properties help composites made with it resist oxidation.
• Thermal stability: Fuel resistant epoxy properties include its resistance to heat, an integral trait for fuel systems that commonly experience considerable fluctuations in temperature.

Composites made with fuel resistant epoxy are ideal for use in a plethora of industrial purposes.

How Fuel Resistant Epoxy is Used in Composites

The flexibility and light weight of fuel resistant epoxy allow composites made with it to be highly customizable. By lengthening or shortening curing time, manufacturers can alter chemical traits, dielectric characteristics, mechanical strength, thermal conductivity, thermal resistance and other epoxy properties. These uniquely tailored epoxy properties make them useful in many industries.

Fuel resistant epoxy is used in composite structures that include: 

• Adhesive bonding: When exposed to fuel, surfaces of composite components bonded with fuel resistant epoxy resist chemicals while maintaining their strength.
• Barrier coatings: Because of its qualities, fuel resistant epoxy is often used as a thin protective barrier to shield a composite’s surfaces and fibers against infiltration by fuel that can cause degradation.
• Linings: Fuel tanks and piping systems that carry fuel are often lined with fuel resistant epoxy to prevent them from leaking or degrading.
• Matrix resin: As the primary binding resin ingredient for fiber-reinforced composites, fuel resistant epoxy often includes fiberglass or carbon fibers that help ensure structural integrity within chemical storage tanks, automotive components for fuel systems, aircraft fuel tanks and other applications where composites are exposed to fuels or harsh chemicals.

Composites made with fuel resistant epoxy are largely immune to damage from chemicals contained in fuels, partly due to the fact that they prevent fuel from permeating their underlying structures. With its ability to retain significant mechanical strength even in harsh environments, fuel resistant epoxy lengthens the lifespans of composites. In fact, epoxy properties allow composites containing it to replace metals or alloys in fuel-related applications.

Applications for Fuel Resistant Epoxy Composites

Fuel resistant epoxy has been modified to withstand a range of different conditions. For example, many epoxy properties have been developed that can withstand conditions where gasoline boils in environments with 100 percent humidity at 85°C (185°F). Such types of fuel resistant epoxy have withstood these harsh conditions without their bond strength degrading both when configured as a film or paste. Modifications to fuel resistant epoxy allow them to match the thermal expansion of the surfaces to which they adhere while also retaining high strength.

Common applications for composites containing fuel resistant epoxy include: 

• Filter casings, fuel pump housings, sensor mounts, and other fuel system components are needed for motor vehicles due to epoxy-based composites’ durability and chemical resistance.
• Epoxies are used to coat aboveground and belowground pipeline systems used for transporting fuel. These epoxies prevent corrosion while keeping fuel from penetrating and structural components from failing.
• Fuel tanks are used in aircraft, high-performance vehicles, and seagoing vessels due to their light weight, strength, and resistance to chemical or fuel permeation.
• Gaskets and seals that are used in places like engine compartments, fuel tanks and systems that handle chemical fluids to keep them flexible while resisting exposure to fuel.
• Fuel storage systems, housings, and structural components, such as fuel-resistant epoxy, can tolerate extreme temperatures and contact with aviation fuel in aircraft and spacecraft.
• Lines and hose systems that deliver fuel for aerospace, automotive, and industrial fuel systems, as they prevent leaking and resist degradation.

Epoxy-based composites play a leading role in today’s oil and gas fields. Fuel resistant epoxy and other thermosets used in composites help companies develop oil and gas deposits in harsh environments under demanding conditions. From the dry heat of oil wells in deserts to the chill offshore gas platforms in the Arctic, epoxy’s properties ensure composites can withstand the most brutal environments.   

Green Fuels & Fuel Resistant Epoxy

Epoxy properties are useful with alternate fuels as well as conventional fuels. Hydrogen-powered buses and trucks are appearing in places around the United States, and many use composites containing epoxy. Epoxy exhibits properties like its excellent strength-to-weight ratio, along with its resistance to chemicals and impermeability to all sorts of fuels.

Hydrogen storage tanks use epoxy-based composites with carbon fiber reinforcement in hydrogen tanks as they endure high pressures well. Hydrogen distribution lines and fuel systems use composites containing epoxy for connectors, fuel lines, seals, and other components that would otherwise become brittle and degrade in the cryogenic temperatures used to store hydrogen fuel. Additionally, many structural components are used in hydrogen-powered vehicles to reduce weight and augment efficiency, while fuel cells are often coated with fuel-resistant epoxy to insulate against electricity and are chemically inert.

Fuel Resistant Epoxy Composites from Spaulding

Spaulding Composites makes fuel resistant epoxy-based composites for both conventional and alternative fuels. Additionally, we make high-quality glass epoxies with cryogenic capabilities for hydrogen and natural gas fuel. To learn more about epoxy properties and whether fuel resistant epoxy will work for your project, contact the composite experts at Spaulding today.