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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.
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).
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.
Polyaspartic ester chemistry was first introduced in the early 1990s making it a relatively new technology. [1] [2] [3] The patents were issued to Bayer in Germany and Miles Corporation in the United States. It utilizes the aza-Michael addition reaction. [4] [5] These products are then used in coatings, adhesives, sealants and elastomers. [6]
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 ...
Solutions of ASA in these solvents can also be used as adhesives. [4] ASA can be glued with cyanoacrylates; uncured resin can however cause stress cracking. ASA is compatible with acrylic-based adhesives. Anaerobic adhesives perform poorly with ASA. Epoxies and neoprene adhesives can be used for bonding ASA with woods and metals. [4]
Polyurethane foam made with an aromatic isocyanate, which has been exposed to UV light. Readily apparent is the discoloration that occurs over time. Custom-cast polyurethane objects. Polyurethane products have many uses. Over three quarters of the global consumption of polyurethane products is in the form of foams, with flexible and rigid types ...