Cyanoacrylate glues
Definition
Introduction to cyanoacrylate glues
Cyanoacrylate glues are a type of instant adhesive based on cyanoacrylate esters, characterized by their ability to polymerize quickly in the presence of humidity, forming strong and resistant bonds. This property makes them very popular adhesives for applications where quick and long-lasting bonding is required.
Since their development in the 1940s and their commercialization in the 1950s, these glues have revolutionized the glue industry due to their ease of use, versatility and high efficiency in joining materials as diverse as plastics, metals, ceramics, wood and rubber.
Composition and chemical properties
Chemical structure of cyanoacrylate
Cyanoacrylate adhesives are primarily composed of cyanoacrylate esters, which are acrylic monomers with a cyano (-CN) group and an ester group. The general formula is CH2=C(CN)-COOR, where R represents an alkyl group that can be varied to modify the properties of the adhesive.
These monomers are highly reactive and polymerize quickly when they come into contact with moisture, forming long polymer chains that generate a rigid and resistant bond. The reaction is exothermic and very fast, allowing almost instantaneous setting.
The speed and strength of the bond depend on the type of cyanoacrylate, the amount of moisture present and the nature of the surfaces to be joined, making it an ideal adhesive for applications that require rapid drying and strong adhesion.
Physical and mechanical properties
Cyanoacrylate glues have a transparent or slightly yellowish color and have a viscosity that can vary from liquid to gel, depending on the formulation. Its adhesion is rapid, reaching initial resistance in seconds and maximum resistance in a few hours.
Mechanically, the joints have high tensile and shear strength, although they can be fragile in the face of impacts or extreme bending. Thermal resistance is usually limited, with degradation above 80-100 °C, although modified formulations exist to improve this characteristic.