Which resin is predominantly used for adhesives in composites?

Which resin is predominantly used for adhesives in composites?

• A. Polysulfides
• B. Silicones
• C. Epoxies
• D. Polyamides

Answer: (C)

In this context, you want a resin that can carry load between fibers, cure to a strong, stiff bond, and withstand temperature and moisture without degrading. Epoxy resins deliver all of that: they wet fibers well, form high interfacial strength with carbon, glass, or other fibers, and provide excellent mechanical properties and environmental resistance. They can be formulated in toughened variants to resist impact, and their cure can be tailored with different hardeners to suit prepregs and various bonding processes used in composites. The other resins have useful specialities—polysulfides for flexible seals, silicones for weathering and gap-filling, polyamides for toughness—but they generally don’t match the overall strength, stiffness, and thermal/chemical performance of epoxies, so epoxies are the predominant choice for structural adhesives in composites.

In this context, you want a resin that can carry load between fibers, cure to a strong, stiff bond, and withstand temperature and moisture without degrading. Epoxy resins deliver all of that: they wet fibers well, form high interfacial strength with carbon, glass, or other fibers, and provide excellent mechanical properties and environmental resistance. They can be formulated in toughened variants to resist impact, and their cure can be tailored with different hardeners to suit prepregs and various bonding processes used in composites. The other resins have useful specialities—polysulfides for flexible seals, silicones for weathering and gap-filling, polyamides for toughness—but they generally don’t match the overall strength, stiffness, and thermal/chemical performance of epoxies, so epoxies are the predominant choice for structural adhesives in composites.