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Surface Tension

Surface Tension and Adhesives

Liquids are made up of many molecules that attract each other. This cohesive force at the surface of a liquid creates what is called surface tension. The magnitude of this property can be either high or low, depending on the strength of the molecular attraction. For example, water has a relatively high surface tension, which is why a small dome can form on top of water in a filled glass.

When it comes to bonding, it is more difficult to glue surfaces with low surface tension. For instance, as shown in the graph below, Teflon (which is used on cookware) is very difficult to bond. Taking silicone bonding as an example, silicone has a very low surface tension (around 24 mN/m). When a material has a lower surface tension than the adhesive being used, bonding will generally not succeed. Therefore, silicone surfaces must be pre-treated, for example by plasma treatment, corona treatment, or by applying a liquid primer to the surface before the adhesive is applied.

 

Materials

  • 19 Polytetrafluoroethylene / PFTE / Teflon
  • 24 Polydimethyl / Silicone
  • 27 Butyl Rubber
  • 31 Polyethylene / PE
  • 31 Polypropylene / PP
  • 31 Natural Rubber
  • 31 Polyisoprene
  • 32 Polybutadiene
  • 32 SBR Rubber
  • 32 Polyisobutylene
  • 33 Polystyrene / Styrofoam
  • 34 Akrylbutadienstyren / ABS
  • 35 Acrylonitrile Butadiene Styrene / PLA
  • 38 Polyurethane
  • 38 Polychloroprene Rubber / Neopren
  • 38 Polybutadiene-Acrylonitrile Rubber
  • 38 Polyvinyl Acetate
  • 39 Polymethyl Methacrylate / Plexiglas / PMMA
  • 39 PVC
  • 39 Celluloseacetat
  • 39 Cellulosenitrat
  • 40 MS-polymer
  • 43 Polyamid / Nylon 6
  • 43 Polyethylentereftalat / Arinite
  • 43 Polyoxymethylen / Delrin
  • 43 polyethylen-terephthalat / PET
  • 44 Polyacrylonitrile
  • 44 Polycarbonate / PC
  • 49 Epoxy
  • 51 Phenol
  • 52 Polyamide-epichlorohydrin
  • 61 Urea-Formaldehyde
  • 68 Wood
  • 900 Aluminium
  • 2000 Steel
  • 3500 Glas