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Ultraviolet Electromagnetic Radiation
Published in Dave Birtalan, William Nunley, Optoelectronics, 2018
UV curing uses electromagnetic radiation in place of a solvent that is traditionally evaporated with heat or left to dry, leaving behind the solid ink or coating material. The environmental standards in place today greatly restrict the use of solvents or volatile organic compounds (VOCs), which evaporate into the atmosphere and are harmful to humans. UV curing uses UV electromagnetic energy (photoenergy) to start a chemical reaction known as photopolymerization. UV curing uses a mixture of fillers, wetting agents, monomers, oligomers, and photoinitiators that creates polymer chains almost instantaneously when UV light is introduced to the mixture. The photoinitiators comprise a very small portion of the mix but readily absorb the UV energy, creating free radicals, which begins the polymerization process. Interestingly, the monomers, oligomers, and photoinitiators all coexist without reacting with each other, until the photoinitiators are exposed to light of the correct wavelength and intensity. This enables UV curing to offer a “cure on demand,” which is an advantage compared to the working time limitations for a solvent-based processes.
Mounting Multiple Lenses
Published in Daniel Vukobratovich, Paul Yoder, Fundamentals of Optomechanics, 2018
Daniel Vukobratovich, Paul Yoder
The long cure times and high temperatures required by the thermosetting adhesives led to development of ultraviolet (UV) curing adhesives, which are now the most common in the optical industry. Curing is initiated in the UV curing adhesives by irradiation with UV light at wavelengths between 354 and 378 nm. A short intense UV illumination lasting 10–20 s tacks the lenses in place, permitting limited handling. Final curing is with a flood UV source, at a lower level, over a period of about an hour. As with the thermosetting adhesives, the shrinkage of UV curing adhesives is inversely proportional to the cure time. Short cure times induce considerable shrinkage and high levels of residual stress.
Beneficial Industrial Uses of Electricity: Materials Fabrication
Published in Clark W. Gellings, 2 Emissions with Electricity, 2020
Electric infrared heating is used in many manufacturing sectors for heating, drying, curing, thermal-bonding, sintering, and sterilizing applications. Sometimes fuel-fired heaters are used in conjunction with electric IR in hybrid systems. Ultraviolet (UV) curing is used for curing inks, coatings, adhesives, liquids, and powdered coatings. UV systems require less energy and have lower volatile organic compound (VOC) emissions than IR or convection ovens, but can only be used with certain coatings for niche applications.
Synthesis and characterization of UV curable biocompatible hydrophilic copolymers containing siloxane units
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Saulutė Budrienė, Tatjana Kochanė, Neringa Žurauskaitė, Evaldas Balčiūnas, Ieva Rinkūnaitė, Karolis Jonas, Raimondas Širmenis, Virginija Bukelskienė, Daiva Baltriukienė
The UV-cured films were formed by casting the formulated solutions onto a poly(propylene) mold and then irradiating under a medium pressure mercury lamp (400 W). The formulated solutions contained 2% of photoinitiator IRG 651 which was calculated on the basis of copolymer solution. UV curing is a process in which ultraviolet light and visible light spectrum in wavelengths from 200 to 480 nm is used to initiate a photochemical reaction that generates a crosslinked polymer network. The cure cycles lasted 10–40 min. To remove the residual solvent, the films were placed into a vacuum oven at 40 °C for at least 12 h. Residual epoxy groups were removed by immersion of the films in 0.125 M ethylene diamine for 30 min at ambient temperature. To remove the residual monomers and linear copolymers, the films were washed in hexane for 1 h, ethyl alcohol for 1 h and in water at ambient temperature for 24 h. Finally, the washed films were dried at 40 °C for at least 24 h. The obtained thickness of the films was about 0.1 mm.
Synthesis of amidoxime polymer gel to extract uranium compound from seawater by UV radiation curing
Published in Journal of Nuclear Science and Technology, 2019
Wijittra Wongjaikham, Doonyapong Wongsawaeng, Peter Hosemann
UV polymerization is widely carried out through photoinitiated reactions and many studies demonstrated that polymerization reactions can occur rapidly by photoinitiated crosslinking of monomers and oligomers. Moreover, because of low energy consumption, UV curing technology has become an environmentally friendly process. Wan et al. [31] prepared a superabsorbent material from kaolinite and poly (acrylic acid - acrylamide) by photopolymerization using Michler’s ketone and benzophenone as photoinitiators. Ruan et al. [32] synthesized superabsorbent resin from acrylic acid (AA) monomer using 700 W UV light with various crosslinking agents and photoinitiators. Results indicated high water absorbency when MBA (crosslinking agent) and Irgacure 1800 (initiator) were used. Dolat et al. [33] synthesized a high-capacity water absorbent agent by UV polymerization without any crosslinker or initiator and result showed high water absorption rate which might be good for industrial applications.
A study on the polymer structures and electro-optical properties of epoxy-mercaptan-based polymer dispersed liquid crystal films
Published in Liquid Crystals, 2019
Chunxin Li, Mei Chen, Wenbo Shen, Gang Chen, Lanying Zhang, Huai Yang
Common strategies used by polymerisation-induced phase separation (PIPS) to prepare PDLC films include UV initiation and thermal initiation [16–20]. The UV curing method can be achieved in short time and low temperature, making the processing easier. However, it has inevitable disadvantages such as yellow stain and the contamination of the remaining radical initiator, which may seriously affect its practical applications [21–23]. By contrast, thermal curing method has attracted huge interest since it has characteristics of lower cost, no yellow stain and less contamination after polymerisation [16,24,25].