ADHESIVES, GLUES AND SEALANTS
What are the fillers in the adhesives?
Fillers are compounds that are part of the adhesives or glues, and have as objective to vary or determine the chemical, physical and mechanical properties of the adhesives, after selection of the monomers and polymers, fillers take on an important role in the composition of the adhesives.
As examples of fillers in the adhesives we find aluminum powder, glass spheres, copper, talc, aluminum oxide, titanium oxide, carbon fibers ...
Depending on the type of material and its type or shape of the filler, the resulting adhesive acquires certain properties, for example, the use of aluminum powder in the form of spheres which reduces the viscosity of the adhesive. The use of glass fibers reduces the shrinkage while increasing the impact resistance of the adhesive, the use of aluminum oxide reduces the cost of the adhesive.
The fillers are included in the adhesive formulation and they may affect the following properties or characteristics of the adhesive itself:
Shrinkage after curing
Mechanical properties such as elongation, impact resistance, elastic modulus ...
Resistance to heat, fire, radiation ...
Coefficient of thermal expansion
Optical properties, color
During the formulation of the fillers that are to be included in the adhesive, you must find a balance between the properties contributed by each type of filler, due it can produce the opposite effect; for example, the use of filler with low viscosity produces the concentration of this fillers in the area of adhesion or interface, preventing the polymer adhesive to adhere to the substrate, on the other hand the use of fillers with high viscosity increase the viscosity of the adhesive properties and deteriorate its wet features, and therefore the adhesion of the adhesive to the substrate.
In recent years the science of adhesives has been focused on the study and development of fillers through the use of nanotechnology, the latest adhesives are implementing this technology, obtaining adhesives with superior properties compare with the adhesives made without nanotechnology.
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