Editing Ultraviolet (section)

====Polymers====
Electronic components that require clear transparency for light to exit or enter (photovoltaic panels and sensors) can be potted using acrylic resins that are cured using UV energy. The advantages are low VOC emissions and rapid curing.

[[File:UV effect on finished wood.jpg|thumb|Effects of UV on finished surfaces in 0, 20 and 43 hours]]
Certain inks, coatings, and [[adhesive]]s are formulated with [[photoinitiator]]s and resins. When exposed to UV light, [[polymerization]] occurs, and so the adhesives harden or cure, usually within a few seconds. Applications include glass and plastic bonding, [[optical fiber]] coatings, the coating of flooring, [[UV coating]] and paper finishes in offset [[printing]], dental fillings, and decorative fingernail "gels".

UV sources for UV curing applications include [[UV lamps]], UV [[LED]]s, and [[excimer]] flash lamps. Fast processes such as flexo or offset printing require high-intensity light focused via reflectors onto a moving substrate and medium so high-pressure [[Mercury (element)|Hg]] (mercury) or [[Iron|Fe]] (iron, doped)-based bulbs are used, energized with electric arcs or microwaves. Lower-power fluorescent lamps and LEDs can be used for static applications. Small high-pressure lamps can have light focused and transmitted to the work area via liquid-filled or fiber-optic light guides.

The impact of UV on polymers is used for modification of the ([[surface roughness|roughness]] and [[hydrophobicity]]) of polymer surfaces. For example, a [[poly(methyl methacrylate)]] surface can be smoothed by vacuum ultraviolet.<ref>{{cite journal|author1=R. V. Lapshin|author2=A. P. Alekhin|author3=A. G. Kirilenko|author4=S. L. Odintsov|author5=V. A. Krotkov|year=2010|title=Vacuum ultraviolet smoothing of nanometer-scale asperities of poly(methyl methacrylate) surface|journal=Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques|volume=4|issue=1|pages=1–11|issn=1027-4510|doi=10.1134/S1027451010010015|bibcode=2010JSIXS...4....1L |s2cid=97385151|url=http://www.lapshin.fast-page.org/publications.htm#vacuum2010|url-status=live|archive-url=https://web.archive.org/web/20130909230837/http://www.lapshin.fast-page.org/publications.htm#vacuum2010|archive-date=9 September 2013|url-access=subscription}}</ref>

UV radiation is useful in preparing low-surface-energy [[polymer]]s for adhesives. Polymers exposed to UV will oxidize, thus raising the [[surface energy]] of the polymer. Once the surface energy of the polymer has been raised, the bond between the adhesive and the polymer is stronger.