An introductory profile of the technology and science behind curing advanced composite systems with UV lighting products and UV curing technology.

1. UV LIGHT CURES, BUSINESS, INTRO & TUTORIAL 1
WE262:
UV Light Cure: How to / the systems.
2017.
INTRODUCTION
The following is a tutorial /a mechanical means of introducing you to the workings and systems
of UV light curing for, and concomitant to fiberglass repairs. The tutorial is informative of the
relevance and utilization of UV lights and UV light curing and the specifics behind how, why,
where, when, and details about the systems involved to successfully carryout the UV ray
induced resin systems. The relevant systems where UV curing systems apply are with epoxy,
vinyl ester, and polyester resins. The lesson covers the use of these materials specifically for
the utilization of these products in the wind industry. The purpose of the lessons are to give you
a vivid understanding of how to carry out these futuristic repairs with the select fibers and the
appropriate resins in your own practice.
This module / assignment involves multiple aspects related to the systems, mixture ratios,
plasticizer properties, functions and applications of additives, and the potential involved to
provide and utilize UV light curing on wind turbine / fiberglass and resin repairs. There are
numerous different “applications” to cure advanced resin systems with UV, though a resin alone
without a UV additive or even with the resins concomitant hardener will not cure by UV
exposure alone. One must be sure to understand this and these materials and also one must
keep an open mind about using new products, and new systems.
With the proper use of UV curing systems a “curing” time of a resin can be knocked down,
potentially from a 30 min or more cure, down to 1-5 minute hardening time, with the use of
proper UV light / UV curing systems. The UV c curing method is an advanced and more
punctilious procedure to speedily cure a resinous fiberglass repair. Potentially saving thousands
of dollars in “wait / cure times”, while opening up a composite technician’s schedule to other
focuses on site. Optimal use of your tools can be a genuine way to be find respect in the
industry.
A small history is provided, and the lesson includes the details needed to carry out repairs
specific to using UV-C lights as a curing mechanism. It is important to understand the
terminology when working with materials “new to you”. There is a small vocabulary lesson
included in Section 1.

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The information is authored for and aimed towards the wind industry, wind turbine
blades, business aspects of blade repair. the assignment also includes the relevant science
behind Ultra-violet light curing systems.
The lesson focuses in on the efforts and systems needed to be successful with the use of UV
light, UV light protection, UV light for curing resin and UV light cured fiberglass repairs, the use
and practice of working with additives, and other details to introduce any individual to the
practice of performing flawless and functional repairs with the UV light systems.
ADVANTAGES OF UV CURES
Curing your repairs with UV lights bring several advantages:
1. Less Waste / Indefinite “working pot life”
There is less waste, because the pot life is accordingly with the actual time “curing” with
the UV light systems.
2. Low Volatile Organic Compounds (VOC) / Low Emissions
There are no emissions with UV light cures, as stated later, there are no emissions
because these kinds of repairs are cured from the exterior inward, meaning that the cure
takes place before emissions are released.
3. UV light: Specialty
UV light cures provide aspects of curing that are available through no other method. This
is true because UV light curing is best and most widely known for the use in such
industries that are “characterized by fast production speeds. (Black, 2004) Recently
surfacing is that the outer gel coat layer on filament – wound pressure tanks have been
UV light cured, in a process developed my Entex composite machines Inc from Salt
Lake City Utah. (Black, 2004)
Complex shapes with variable shapes and thicknesses make UV light cures tricky. “You
have to invest time and money to optimize all the variables like lamp intensity, position,

3. UV LIGHT CURES, BUSINESS, INTRO & TUTORIAL 3
the
“best” products, prices and so forth.”( [Folda, 2004] Black, 2004)
4. Decreased time needed for material to cure / setup.
UV TERMINOLOGY & USE.
(Read the information located at the links below)
1. Resin Doming
– Resin doming, is a manufacturing process of “sealing” and covering certain materials
with a “dome of resin”. (Witness this definition by the producing firms.)
http://www.epoxies.com/products/
https://www.youtube.com/watch?v=sWbPK5Px1i0
2. Types of UV light –
(nm = measuring of light wavelengths. “Seeing” in plain daylight can be measured as a
555 nm wavelength”) (Schawlow, 1969)
a. UV-A (315-380 nm)
b. UV-B (280-315 nm)
c. UV-C (100-280 nm)
The UV light needed to cure the resin by “photopolymerization” or with a “photo initiator” is
and should be listed within the product specifications of the UV light curing product that you
purchase; the original manufacturer should supply you with the correct UV light to use to
cure your resin. (Shaw, 2013., (pg.9)
3. Dangerous emissions.
In polyester and vinyl ester, the speed and natural process of UV curing, styrene
emissions are minimal. This is also true with epoxy’s concomitant chemicals that
“threaten” clear breathing and even may cause a burn: amines, and poly amides, as
emissions may not be severe poisons but they are still a threat to unprotected health.

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(Malmgren, n.d.) Resins at high temperatures may be a flammability hazard, while also
thermodynamic “laws” always apply with all materials. UV curing is said to cure by the
process of “photopolymerization”. (Senlights, n.d.)
4. Thermodynamics -
“Science of the relationship between heat, work, temperature, and energy. Science that
deals with the transfer of energy from one place to another anf from one form to another.
A key concept is heat is a form of energy corresponding to a definite amount of
mechanical work.” (Encyclopedia Britannica, 2017)
5. Photo-polymerization –
“Any process in which relatively small molecules, called monomers, combine chemically
to produce a very large chainlike or network molecule, called a polymer”; in which in
photo-polymerization :this curing process takes place by the materials interaction with
specified wavelengths of light. (Encyclopedia Brtannica, 2017)
6. Photo initiator-
“An agent which when exposed to a specific waveband of light, starts a chain reaction in
the formation of a resin polymer. Common photo initiators are “benxoyl peroxide”, and
“Camphorquinone”. (Oxford Reference, 2017)
7. Pollution degree –
A classification according to the amount of dry pollution and condensation present in the
environment. (National Instruments, 2006)
7. Viscosity

5. UV LIGHT CURES, BUSINESS, INTRO & TUTORIAL 5
A measure of the resistance of a liquid to sheer forces and therefore to flow. Very resistant /
harder to pour: a higher “unit” / number. Each “liquidity” has its own number of viscosity.
(Oxford Reference, 2017)
8. Thixotropic / Thixotropy
“A property possessed by certain gels as a result of which they become liquid when stirred
and return to a gel like state when left to stand.”. (Macmillan Encyclopedia, 2003)
9. Anaerobic
Such organism and materials that do not require oxygen or which oxygen would
potentially damage. (Oxford Reference [Aneroebic], 2017)
10. Cationic
“Of a cation or cations (positively charged ion). (Oxford Reference, [cationic], 2017)
11. Acrylates
https://nems.nih.gov/soc/Pages/Acrylates.aspx
12. Specific Gravity
https://van.physics.illinois.edu/qa/listing.php?id=5454
History / Wavelength
Schawlow, L. Aurthur. (1969). Lasers and Light:
“Spectrum of light encompasses the narrow band of radiant energy to which the human eye is
sensitive, a portion of the electromagnetic spectrum from about 400 to about 700 nanometers in
wavelength. The Human eye sees in peak daylight: at 555 nm.” (Schawlow, 1969,Pp 9) UV
lamps and lights range from the 100 nm -400 nm (Schawlow, 1969)
Other Contributing Factors:

6. UV LIGHT CURES, BUSINESS, INTRO & TUTORIAL 6
• Lamp intensity.
• Position of lamps.
• Resin mix / mixtures.
• Max depth of cure between 13mm and 19 mm (Curing only: 1/2 inch to 3/4 inch deep at one
time). (Shaw, 2013)
• UV light can only penetrate optically transparent materials - glass fiber etc. (Carbon fiber is a
more arduous task because of its overall “opaqueness”. (Black, 2013)
• Carbon fiber and aramid fiber which are opaque can only be used by curing each ply
separately, and individually. (This is because of the opaqueness of the material and the
effectiveness of the light waves actually reaching the materials timely and sufficiently)
(Shaw, 2013)
• Calcium carbonate or typical resin fillers cannot be used, because the prevent full
penetration of the light.
• It is possible to cure cored composites: if the core is transparent like polypropylene
honeycomb or if the outer skin is laid up and cured first: as the inner solid core and inner
skin must be laid up and cured separately from the outer coming layers of fabric / resin
application.
• To cure effectively the light must reach the entire part to be cured, and all “UV photo
sensitive resin”, so shadows caused by the part curvature, or by fixtures such as vacuum
bag hoses, or fittings, all of these materials must be absent from the curing process, for the
curing process to be “clean of obstacles”.
• Process cures the resin from the Top, in, meaning that emissions are expunged / eradicated
completely!
• The cross linking happens very quickly yet this involves the elimination also of air voids,
because of the rapidity of the cure. ([Mark Livesay of Sunrez Corp. El Cajon, Calif., U.S.A.]
Black, 2003)
• Increases production speed.
• Reduces “reject” rates.
• Improves scratch and solvent resistance.
• Facilitates superior bonding of resin etc.
• UV lights for Open molding processes are usually “large and three dimensional” therefore
UV curing is done in the “Far spectrum” (not in focus). It is recommended that UV lights for

7. UV LIGHT CURES, BUSINESS, INTRO & TUTORIAL 7
curing Open molding pieces :provide “higher irradiance over a larger spectrum of the
material”. (Haraeus, n.d.)
• [DISADVANTAGE]: gel coat curing may require different bulb types depending on the
specific formulation. V bulb for adequate through cure; and H bulb is used for clear gel
coats: [http://www.fusionuv.com/uv_bulbs.aspx ].
UV for different methods:
1. Filament winding -
2. Pultrusion
3. Open molding
4. Preforming
5. Vacuum Infusions
Disposal
It is recommended to throw away resins that have completely cured, or are still “unbonded”
resins yet have expired due to the quality of the bonding the materials, and therefore the
quality and durability / authenticity of the potential bonds. Thermodynamics and awareness
to poisonous substances is crucial when throwing these kinds of high qaulity materials
away. Be aware of spontaneous combustion, exothermic materials, potential ignition due to
chemical interactions, enclosed containers, the temperature of the location of the enclosed
container, etc.
Each lifespan or life expectancy of a UV lamp or bulb differs according to manufacturer
standards or protocol. Each bulb or lamp life differs according to the manufacturer. It is not
uncommon for a manufacturer to have a warranty on the bulbs, and/or lamps, and a typical
lifespan of a lamp or light may exceed or compete with the lifespan of 6000 to 8000
operating hours. [ http://www.fusionuv.com/uv_bulbs.aspx ]
“Any safety or disposal regulations that EPA or OSHA applies to fluorescent lamps also apply to
UV lamps. Heraues Noblelight America accepts used bulbs for disposal if they are sent in
appropriate protective packaging at the customer’s expense.
http://www.fusionuv.com/uv_bulbs.aspx ]

8. UV LIGHT CURES, BUSINESS, INTRO & TUTORIAL 8
Harm of UV
Safety
UV – A lights – can cause harm, prematurely age your skin, and can cause wrinkling and “age
spots”.
UV-B lights are damaging as that of the sun’s rays. UV-B lights can burn the skin, as well as
cause skin cancer, skin melanoma.
The best protection is complete protection; a complete PPE setup is recommended: UV
resistance glasses, a sufficient lab coat or “fire retardant long sleeve shirt) or lab-coat /
Tyvek suit, respirator impenetrable gloves and steel toed boots. Pay attention to all OEM
instructions, with both your lights and resins.
Take a peak at these websites (Safety):
1. https://www.ehs.uci.edu/programs/radiation/UV%20Lamp%20Safety%20Factsheet.pdf
2. https://www.osha.gov/SLTC/styrene/index.html
3. https://www.cdc.gov/niosh/topics/chemical-safety/default.html
Products
1. http://www.epoxies.com/products/uv-curable-illumabond/
2. http://www.gurit.com/Our-Business/Composite-Materials/Other-Products/Repair-
Solutions/RENUVO-Lamp-Technology
http://www.gurit.com/Our-Business/Composite-Materials/Other-Products/Repair-
Solutions/RENUVO-Multi-Purpose-System
3. https://www.cureuv.com/collections/uv-curing-handheld-devices - Lights
4. http://www.fiberglasssupply.com/Product_Catalog/Fillers/fillers.html
5. http://solarez.com/our-products/
https://www.covascientific.com/uv-
adhesive?utm_source=bing&utm_medium=cpc&utm_campaign=Epoxy%20UV&utm_ter
m=%2Buv%20%2Bepoxy&utm_content=UV

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6. https://www.covascientific.com/uv-
adhesive?utm_source=bing&utm_medium=cpc&utm_campaign=Epoxy%20UV&utm_ter
m=uv%20epoxy%20resin&utm_content=Resin – UV-A and UV-B sensitive products.

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References
Black, S. (2004). Composites Technology. UV Curing Article. Retrieved April 29, 2017 from
http://www.swaylocks.com/groups/uv-curing-article .
Encyclopedia Britannica [ Polymerization]. (2017). Polymerization, [Photo-polymerization].
Encyclopedia Britannica. Retrieved May 2, 2017 from
http://lccc.summon.serialssolutions.com/search?q=photo+initiator&fvf=IsFullText%2Ctrue&fv
f=ContentType%2CDissertation%2Ct&spellcheck=true&keep_r=true#!/search?ho=t&fvf=IsF
ullText,true,f%7CContentType,Dissertation,t&l=en&q=photopolymerization .
Encyclopedia Britannica [Thermodynamics]. (2017). Thermodynamics. Encyclopedia Britannica.
Retrieved May 2, 2017 from
http://proxy.lccc.wy.edu:2097/levels/collegiate/article/thermodynamics/108582 .
Heraeus Noblelight America LCC. (n.d.) What is UV Curing? Retrieved April 29, 2017 from
http://www.fusionuv.com/uvlearningcenter.aspx?id=206
Heraeus Noblelight America LCC. (n.d.). UV systems for Composites. Retrieved May 2, 2017
from http://www.fusionuv.com/Products.aspx?id=148 .
Malmgren, N. AB. (n.d.). Safety when working with epoxy and hardener. Nils Malmgren AB.
Retrieved May 2, 2017 from
http://www.nilsmalmgren.com/epoxy-chemistry/safety-when-working-with-epoxy-and-hardener/
National Instruments. (2006) Pollution Degree rating for electrical equipment. SHOP. Retrieved
April 29, 2017 from http://www.ni.com/white-paper/2871/en/ .
Oxford Reference [Anaerobic]. (2017). Anaerobic. Retrieved May 2, 2017 from
http://proxy.lccc.wy.edu:2094/view/10.1093/acref/9780191826320.001.0001/acref-
9780191826320-e-329 .
Oxford Reference. [Cationic]. (2017). Cationic Retrieved May 2, 2017 from
http://proxy.lccc.wy.edu:2094/view/10.1093/acref/9780195517965.001.0001/m-en_au-
msdict-00001-0008894 .
Oxford Reference.[Photo-initiator]. (2017). Photo-initiator. Oxford Reference [online
Encyclopedia]. Retrieved May 2, 2017 from
http://proxy.lccc.wy.edu:2094/view/10.1093/acref/9780199533015.001.0001/acref-
9780199533015-e-3376 .
Oxford Reference [Viscosity] (2017). Viscosity. A Dictionary of Environment and Conservation.
(3 ed.) Retrieved May 2, 2017 from
http://proxy.lccc.wy.edu:2094/view/10.1093/acref/9780191826320.001.0001/acref-
9780191826320-e-8707 .

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Senlights. (n.d.) UV CURING technology. Senlights (online). Retrieved May 2, 2017 from
http://www.senlights.com/gijyuu/uvcure/UVcuring.html .
Shaw, J. Ph.D. (2013) Advantages of UV Curing in Composite Manufacturing. CYTEC.
Retrieved May 2, 2017 from
http://www.uvebwest.com/presentations/Advantages%20of%20UV%20Curing%20in%20Co
mposite%20Manufacturing.pdf
The Macmillan Encyclopedia. (2003). Thixotropy. The Macmillan Encyclopedia. Retrieved May
2, 2017 from http://proxy.lccc.wy.edu:2134/content/entry/move/thixotropy/0 .