High molecular weight cyanoacrylate

Manuticturers Comments Ethyl cyanoacrylate. Fast cure for difficult Manufocturers Comments High molecular weight cyanoacrylate. No ... 

This difference in reactivity between the different classes of amines explains the difference in the primer performance on polyolefin substrates with ethyl cyanoacrylate-based adhesives [37J. Since primary and secondary amines form low molecular weight species, a weak boundary layer would form first, instead of high molecular weight polymer. Also, the polymer, which does ultimately form, has a lower molecular weight, which would lower adhesives strength [8,9]. 

The second stage of cyanoacrylate polymerization, propagation, occurs after the formation of initiated monomer (8). This species attacks another monomer molecule to generate a dimeric species (9, Eq. 5), which reacts with more monomer until a high molecular weight polymer chain (10) is formed. The molecular weight of the polycyanoacrylate formed is probably... 

The disadvantages of epoxies include their two-component (or heat-cure) form, reduced performance on oily snrfaces, their inherent lack of toughness, and limited performance on thermoplastics reactive acrylics, cyanoacrylates and polyurethanes are usually superior in such departments. Also, the base resins are relatively high-molecular-weight species, so it is not possible to formulate very-low-viscosity adhesives unless reactive diluents are added, with a corresponding drop in performance. 

Manufacture and Processing. The cyanoacrylic esters are prepared via the Knoevenagel condensation reaction, in which the corresponding alkyl cyanoacetale reacts with formaldehyde in the presence of a basic catalyst to form a low molecular weight polymer. The polymer slurry is acidified and the water is removed. Subsequently, the polymer is cracked and redistilled at a high temperature onto a suitable stabilizer combination to prevent premature repolymerization. Strong protonic or Lewis acids arc normally used in combination with small amounts of a free-radical stabilizer. 

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