Adhesives and Sealants Tutorial - Bonding Mechanisms
Bonding Mechanisms
Adhesion, both for adhesives and sealants, occurs in one of three ways:
Covalent Chemical Bonding, Mechanical Interlocking or Electrostatic Attraction
. Chemical bonding is probably the most desirable method, but the others offer
some distinct advantages.
Covalent Chemical Bonding Covalent chemical bonding uses mutually
reactive chemical groups on the substrate and adhesive to form the strongest,
most durable bond. This is the primary method used to bond smooth materials
like glass or metal.
Mechanical Interlocking Mechanical interlocking bonds materials
together by allowing the adhesive or sealant to take advantage of the
microscopic roughness of the substrates to lock them together.
Electrostatic Attraction Electrostatic attraction uses the ability
of polar groups in the adhesive to be attracted to those in the substrate.
Substrates such as polyethylene do not have polar groups, so usually no
molecular attraction occurs, which results in poor adhesion.
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