The two qualities required for high strength, creep and environmental resistant structural adhesives that unmodified resins often lack are flexibility and toughness. Formulators have overcome these problems either by flexibilizing the molecular structure or incorporating toughening modifiers into the adhesive.
However, flexibilizers present a major problem for both the adhesive formulator and end-user. As they improve elongations but reduce other valuable properties.
Whereas, toughening agents using micro and nano-sized entities improve fracture toughness and impact strength without significantly affecting other properties of the base resin as flexibilizers do.
So, how does toughening agents work? Is there any difference between flexibility and toughness? Read more to discover the best techniques to toughen your structural adhesive.