Search results
Results From The WOW.Com Content Network
In chemistry, a photoinitiator is a molecule that creates reactive species (free radicals, cations or anions) when exposed to radiation (UV or visible). Synthetic photoinitiators are key components in photopolymers (for example, photo-curable coatings, adhesives and dental restoratives).
UV stabilizers in plastics usually act by absorbing the UV radiation preferentially, and dissipating the energy as low-level heat. The chemicals used are similar to those in sunscreen products, which protect skin from UV attack. They are used frequently in plastics, including cosmetics and films. Different UV stabilizers are utilized depending ...
A photopolymer or light-activated resin is a polymer that changes its properties when exposed to light, often in the ultraviolet or visible region of the electromagnetic spectrum. [1] These changes are often manifested structurally, for example hardening of the material occurs as a result of cross-linking when exposed to light.
Cationic polymerization is used in the curing of epoxy resins in the presence of UV in the industry. [16] Light energy from UV breaks apart photoinitiaters, forming an acidic solution which then donates a proton to the polymer. The monomers then attach themselves to the polymer, forming longer and longer chains leading to a cross-linked network.
The chemistry of the resin (for example an epoxy resin would use an epoxy reactive diluent) [4] The flexibility of the cured layer; The volatility; The environmental compatibility. [5] Reactive diluents used are low-viscosity, mono-, bi- or polyfunctional monomers or oligomers. In general, several different monomers are combined so that one ...
PETA is part of a family of acrylates used in epoxy resin chemistry and ultraviolet cure of coatings. Similar monomers used are 1,6-hexanediol diacrylate and trimethylol propane triacrylate. It is a derivative of pentaerythritol [2] One of the key uses of the material is in polymeric synthesis where it can form micelles and block copolymers.
The biggest quantity of stabilizers is used for polyvinyl chloride (PVC), as the production and processing of this type of plastic would not be possible without stabilizing chemicals. [1] Common polymer degradation processes include oxidation , UV-damage , thermal degradation , ozonolysis , combinations thereof such as photo-oxidation , as well ...
The Norrish Type I reaction plays a crucial role in the field of photopolymerization, particularly in the development of photoinitiators used for two-photon polymerization (2PP). The Norrish Type I reaction is particularly significant here because it involves the cleavage of a carbon-carbon bond in a photoinitiator molecule upon excitation by ...