Adhesives Magazine

Ask Dr. Dave

June 1, 2009
In his June 2009 column, Dr. Dave Dunn discusses cyanoacrylate glue and the best adhesives for bonding polyolefin plastics.

Question: I build guitars as a hobby, and I also participate in a forum for guitar builders in which the question about the longevity of cyanoacrylate glue has arisen.  What are your thoughts on its durability and longevity?

Answer: I have been working with cyanoacrylate super glues since 1975. The only thing you must be careful about is temperatures above about 200°F in which the glue will soften; it is a thermoplastic (like polystyrene) and not a thermoset (like an epoxy). Also, excessive water or very high humidity will degrade the glue, though this is not usually a problem unless the bond is under a very high load. In the case of your guitars, I would not anticipate any long-term durability problems.

Question: Do you know of any reactive vinyl, methacrylate or acrylate additives that will attack polyolefin plastics such as polyethylene or polypropylene? 

Answer: I presume that by “attack” you mean enhance the bonding to these plastics. Polyolefins are notoriously difficult to bond because they are composed entirely of carbon and hydrogen atoms without other elements such as oxygen, nitrogen, chlorine, etc. They are known commonly as “non-polar” or “low-energy” plastics. Monomers, such as methyl methacrylate, are known to soften these plastics to a certain extent, and this monomer is the basis of tough acrylic or “methacrylate” adhesives. However, to get really good bonds to polyolefins, the best method is to use a methacrylate adhesive that contains an organoborane additive. It is also possible to get strong bonds to polyolefins with cyanoacrylate adhesives through the use of special surface primers.

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