Additives super glue

In addition to poly(methyl methacrylate) plastics and polyacrylonitrile fibres, acrylic polymers find widespread use. First introduced in 1946, acrylic rubbers have become established as important special purpose rubbers with a useful combination of oil and heat resistance. Acrylic paints have become widely accepted particularly in the car industry whilst very interesting reactive adhesives, including the well-known super-glues are also made from acrylic polymers. 

Super glue is an addition polymer of the following monomer. Draw a structural formula for a three-unit section of super glue. 

The a-alkyl cyanoacrylate super glues ( one drop holds 5000 lbs ) are now a familiar part of the consumer market. Originally, the monomers had extremely low viscosities and so could crawl into narrow crevices and wet the adherend surfaces rapidly. On the other hand, they would not fill gaps and were absorbed into porous adherends, giving poor bonds. Newer versions are available with higher viscosities to overcome these drawbacks. Cyanoacrylates can polymerize in seconds by an anionic addition reaction believed initiated by hydroxyl ions from water adsorbed on the adherend surfaces ... 

In contrast to the condensation polymerisation reaction for epoxy resins, another fast-acting fixing agent. Super Glue , uses an addition reaction to stick objects together. The monomer is CH2= C(CN)COOCHj, methyl cyanoacrylate, and the addition takes place across the carbon-carbon double bond. The polymerisation reaction is initiated by the presence of moisture. 

This additive is now used in some consumer grades of super glue because it reduces the dependence on surface moisture to cure and ultimately leads to good bond strength on many substrates. 

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