Oxygen inhibition of cure

Oxygen inhibition of cure which exists in many energy-curable resins necessitating the use of inert blanketing. 

With the light curing mechanism, there is a limitation to the penetration of the light. The dentist may have to place a restoration that is 6 + mm thick, whereas the light may penetrate only 2 mm [182]. Factors that affect this penetration are the translucence of the material, the color or shade used to match the tooth, the ability to place the light source close to the material being polymerized, and the intensity of the source. Under relatively ideal conditions, the mean depth of cure is approximately 4-5 mm. Thus, the dental application requires that the material be placed in layers. Due to the oxygen inhibition of the outside surface of the resin layers, additional layers can be laminated and cured with the appearance of uniformity of the final restoration. 

Inhibitor Substance that, in low concentration, inhibits chemical reactions, for example, oxygen inhibitation of radiation-curing adhesives. 

Cost effective if done on large scale New technology less familiar to users Oxygen inhibition of surface cure... 

A final layer consisting of one or two light surface veils is normally applied. The resin used for this outer layer may typically contain up to 0.5 wt% of paraffin wax and possibly a UV stabilizer. It main function is aesthetic but it also fulfils other purposes. The paraffin wax will bloom to the surface of the uncured resin. This will seal the surface and prevent air contact, thus avoiding any difficulties which may arise due to oxygen inhibition of the resin curing process. The wax also acts as a UV stabilizer and protects the vessel from attack by the sun in climates where this is an issue. 

Owing to their liquid or semisolid nature, monomers are easy to process into polymers. For radical polymerization the use of solid AIBN for liquid monomers at room temperature and liquid MEKP for semisolid monomers or a mixture of liquid and semisolid monomers with some heating is convenient. During the course of curing at 85- 100°C for 22 h the problem of surface inhibition of free radicals by oxygen from the air can be avoided by inert-gas blanketing. 

All films were touch-dried after one passage through the Mini-Cure (i.e. no oxygen inhibition was noticed). Raman spectra of the resins before and after curing showed no detectable amount of residual unsaturation (i.e. less than 5%). This showed that all acrylate groups are accessible to polymerization and not caged in the hyperbranched structure. 

The penetration depth of electrons into substrate decreases at lower energy. Consequently, the surface dose increases and thin coatings and inks can be cured with higher efficiency and speed. The higher surface dose produces a higher concentration of radicals, which in turn reduces the oxygen inhibition. 

Common thermosets are cured by a free radical addition mechanism. These types of composites are cured by heat initiators, such as peroxides, or by photo initiators, such as a-diketones. A characteristic of cured acrylates is large shrinkage in the course of polymerization, which is undesirable for many uses. Another undesirable characteristic of acrylates is the formation of an oxygen-inhibited layer on the surface upon curing. 

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