The Problem with Rigidity in Epoxy Adhesives

Decrease O- Number Decrease in secondary force Attractions between  

Modulus, Hardness decreases Elongation increases Peel, Flex values increase Impact, Low temp, properties increase Permeability to H20, Solvents increase Resistance to chemicals decreases Thermal aging, Hot strength decreases 

FIGURE 3.10 Relationship between cured epoxy molecule in physical properties. 

The major problem is that the attainment of properties such as peel, flexibility, and toughness is generally accompanied by the reduction in properties such as heat resistance, chemical resistance, and shear strength. Future chapters discuss how the epoxy adhesive formulator can merge these properties. 

It should also be emphasized that the epoxy resins are only building blocks in the development of epoxy-based adhesives. The formulation will ultimately involve one or more epoxy resins curing agents modifiers, such as plasticizers, flexibilizers, accelerators, stabilizers, and flow control agents and fillers. In general, flexibility can be controlled by the parameters shown in Table 3.8. 

---