Structural Adhesive Properties

(Courtesy 3M)

Selecting a structural strength adhesive for a specific application requires performance criteria of several characteristics. First are bond-making properties that determine ease of use and in-place manufacturing cost:

Degree of surface preparation necessary 
Time to handling strength  
Cure conditions of heat or room temperature, the degree of pressure, and the fixturing to maintain that pressure  
Viscosity for pumping and staying in place after application. Pseudoplastic and thixotropic qualities are desireable so that the adhesive thins during the shearing action of delivery and thickens in place without further shearing.  
Application with automated bulk systems or hand-held applicator to meet varying production requirements.

Then there are the following cured bond properties:

Physical Properties

Adhesion to a variety of substrates allows bonding of dissimilar materials if necessary  
High cohesive strength is desirable  
Flexibility improves peel strength by flexing with peel stress  
High elastic modulus of substrate and adhesive resists stress at the bond line  
High damping capacity of the adhesive dissipates dynamic stresses of vibration, motion, & impact throughout the bond & peel stresses at the bond line   
Flexibility and damping resistance resists thermal expansion stresses when the coefficients of thermal expansion are different between adhesive and substrates

Environmental Resistance

Resists end-use or post-processing temperatures to maintain adhesive chemistry and the physical bond  
Withstands physical shock at a range of temperatures  
Maintains adhesive performance despite exposure to UV light, rain, salt water, and other weathering conditions

Chemical Resistance

Ability to withstand degradation from diesel fuel, solvents and other chemicals