Since first discovered in 1943, epoxy adhesives have gained a solid reputation in industries that require optimum performance and reliability. Epoxy adhesives are widely used in the aerospace, automotive, electrical / electronic, construction, and medical industries. The primary reason for the broad acceptance of epoxy adhesives in so many markets is their capacity to provide a good balance of handling characteristics and ultimate physical properties.
The advantages and disadvantages of epoxy adhesives are compared generally to other structural adhesives in Table 1. Epoxy adhesives are relatively inexpensive materials that are available as solventless resins, solvent solutions, water based dispersions, and solids (e.g., film and powder). They adhere well to a wide range of substrates, offer resistance to many environments, and can be formulated to provide pot lives and cure rates that can be adjusted to meet practical production requirements.
However, unmodified epoxy resins cause certain problems for both the adhesive formulator and end-user. Unmodified epoxies are often rigid and brittle; hence, impact resistance and peel strength are poor.