Emerging structural adhesive chemistries and innovations

A wide range of structural adhesive formulations based on diverse chemistries have been developed over the past decades to address design and manufacturing needs in prominent industries such as aerospace, construction, automotive, and others. Structural adhesives in such applications are commonly treated as linear elastic, with loading safety factors derived from experience or from fracture mechanics. However, applications such as crashworthy structural automotive components and military protective systems require bonds to be designed for both rigidity and the expectation of overload failure, revealing gaps in the catalog of existing chemistries that are typically either strong or ductile, but seldom both (and sometimes neither). Additionally, structural adhesives formed by irreversible curing reactions tend to create challenges for maintenance, upgrading, and recycling of components in bonded assemblies, thus stimulating the need to develop adhesives with additional attributes such as debondability. Difficulties overcoming current product limitations are exacerbated by the current state of technical data standardization, which is poor due to the inherent complexity of adhesive bond processing, resulting in cost-prohibitive validation and modeling requirements and thereby loss of market growth potential for the adhesives industry at large. This chapter highlights emerging innovations in structural adhesive chemistry, formulation, and usage targeted at addressing these challenges.