Stronger, more flexible adhesive can enable design of lighter vehicles

Structural adhesives play a crucial role in assembling automobiles, aircraft, and buildings. Among these, epoxy adhesives stand out for their exceptional mechanical strength and durability. However, traditional cured epoxy resins are often rigid and lack flexibility, resulting in low peel and impact strength.

Now, a groundbreaking advancement in structural adhesives has emerged from the laboratories of Nagoya University, promising to transform material bonding as we know it. This next-generation adhesive boasts an unprecedented impact strength – 22 times higher than conventional epoxy-based adhesives without rubbery additives.

By utilizing this stronger and more flexible adhesive to connect car parts, manufacturers can now produce vehicles with lighter components such as aluminum and fiber-reinforced plastic. This innovation holds the potential to revolutionize the automotive industry and beyond.

“Structural adhesives with high strength and durability are essential in the assembly of automobiles, aircraft, and buildings,” Nagoya University researcher Atsushi Noro explains.

“Epoxy resin-based adhesives are widely used; however, they lack flexibility, making them susceptible to damage under impact. To overcome this, we combined a hydrogen-bonded styrenic thermoplastic elastomer with an adhesive, resulting in a new type that offers both flexibility and outstanding impact resistance.”

Developed in collaboration with Aisin Chemical Company and with support from the New Energy and Industrial Technology Development Organization (NEDO), this innovative adhesive opens up a whole new world of possibilities for hydrogen-bonded styrenic thermoplastic elastomers, a previous creation of Nagoya University.

The development of a hydrogen-bonded styrenic thermoplastic elastomer represents a significant leap in the world of polymer science. This unique material possesses rubbery properties, allowing it to stretch and then effortlessly return to its original shape. This remarkable characteristic has paved the way for the creation of a highly resilient adhesive that excels in dissipating stress during impact.

Moreover, the formation of hydrogen bonds within the elastomer enables the adhesive to swiftly separate and reconnect under stress, thereby enhancing its overall toughness.

This groundbreaking advancement has far-reaching implications, particularly in the automotive industry. It directly addresses the pressing need for stronger, more adaptable adhesives capable of securely bonding dissimilar materials in the context of lightweight, multi-material vehicle designs.

“Structural adhesives are expected to play a key role in reducing vehicle weight, which is critical for improving fuel efficiency and lowering emissions,” Noro said. “The adhesive’s ability to bond various materials, such as metals and fiber-reinforced plastics, enables the design of lighter vehicles without compromising safety or performance. This development is a significant step forward in the pursuit of a carbon-neutral society.”

Envisioned as an invaluable tool in the automotive industry’s drive for sustainability and performance, researchers anticipate its potential to revolutionize other sectors like aerospace and construction. By reducing material weight and enhancing carbon efficiency, this innovation promises to reshape heavy industries for the better.

Journal reference:

1. Saya Yamada, Takato Kajita, Mio Nishimoto, Junko Horiuchi, Yoshirou Fujii, Kazumasa Sakaguchi, Kazuo Hattori, Hiroshi Tamura, Tatsuya Kano, Takenobu Sakai, Atsushi Noro. Next-Generation Structural Adhesives Composed of Epoxy Resins and Hydrogen-Bonded Styrenic Block Polymer-Based Thermoplastic Elastomers. ACS Applied Materials & Interfaces, 2024; DOI: 10.1021/acsami.4c12540