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Epoxy Resin
What is epoxy
resin?
by
The term epoxy has been widely adapted for many uses beyond
fiber reinforced polymer composites.
Today, epoxy adhesives are sold in local hardware stores, and
epoxy resin is used as the binder in countertops or coatings for floors.
The myriad of uses for epoxy continues to expand, and variates
of epoxies are constantly being developed to fit the industries and products they
are used in.
Here are some things that epoxy resin is used in:
· General purpose adhesives
· As the binder in cement and mortars
· Rigid foams
· Non-skid coatings
· Solidifying sandy surfaces in oil
drilling
· Industrial coatings
· Potting and encapsulating media
· Fiber reinforced plastics
In
the realm of fiber reinforced polymers (plastics), epoxy is used as
the resin matrix to efficiently hold the fiber in place. It is compatible
with all common reinforcing fibers including fiberglass, carbon
fiber, aramid, and basalt.
Common Products for Fiber Reinforced Epoxy
· Filament Winding
· Pressure vessels
· Pipes
· Rocket housings
· Recreational equipment
· Pultrusion
· Insulator rods
· Arrow shafts
· Compression Molding
· Aircraft parts
· Skis and snowboards
· Skateboards
· Circuit boards
· Prepreg and autoclave
· Aerospace components
· Bicycle frames
· Hockey sticks
· Vacuum Infusion
· Boats
Obviously, there are much more FRP composite products
manufactured from epoxy, but mentioned were a few products that are commonly
manufactured with epoxy and with a particular manufacturing process.
Additionally, the same epoxy resin likely cannot be used for
each of the mentioned processes.
Epoxies are fine-tuned for the desired application and
manufacturing process. For example, protrusion and compression molding epoxy
resins are heat activated whereas an infusion resin might be an ambient cure
and have a lower viscosity.
When compared to other traditional thermoset or
thermoplastic resins, epoxy resins have distinct advantages, including:
· Low shrink during cure
· Excellent moisture resistance
· Excellent chemical resistance
· Good electrical properties
· Increased mechanical and fatigue strength
· Impact resistant
· No VOCs
· Long shelf life
Chemistry
Epoxies are thermosetting
polymer resins where the resin molecule contains one or more epoxide groups.
The chemistry can be adjusted to perfect the molecular
weight or viscosity as required by the end use.
There are two primary types of epoxies, glycidyl epoxy and
non-glycidyl.
Glycidyl epoxy resins can be further defined as either
glycidyl-amine, glycidyl ester, or glycidyl ether. Non-glycidyl epoxy resins
are either aliphatic or cyclo-aliphatic resins.
One of the most common
glycidyl epoxy resins is created using Bisphenol-A and is synthesized in a
reaction with epichlorohydrin.
The other frequently used type of epoxy is known as novolac
based epoxy resin.
Epoxy resins are cured with
the addition of a curing agent, which is commonly called a hardener.
Perhaps the most common type of curing agent is amine based.
Unlike in polyester or vinyl ester resins where
the resin is catalyzed with a small (1-3%) addition of a catalyst, epoxy resins
usually require the addition of the curing agent at a much higher ratio of
resin to hardener, often 1:1 or 2:1.
As mentioned, the properties
of epoxy can be altered and tweaked to fit the desired need. Epoxy resin can be
"toughened" with the addition of thermoplastic polymers.
Prepregs
Epoxy resins can be altered
and impregnated into the fiber and be in what is called a B-stage. This is how
prepregs are created.
With epoxy
prepregs, the resin is tacky, but not cured. This allows layers of
prepreg materials to be cut, stacked and placed in a mold.
Then, with the addition of heat and pressure, the prepreg can be
consolidated and cured.
Epoxy prepregs and the epoxy B-staged film must be kept at a low
temperature to prevent from premature curing.
Because of this, companies using prepregs must invest in
refrigeration or freezer units to keep the material cool.
Todd Johnson
· Regional Sales Manager for Composites One, a distributor
of composite materials.
· B.S. in Business Management from University of
Colorado Boulder's Leeds School of Business
· Business Development Manager for Ebert Composites
Corporation
Experience
Todd Johnson is a former writer for ThoughtCo, who wrote about
plastics and composite materials for 2-1/2 years between 2010 and 2013. He is a
Regional Sales Manager at Composites One, a composite materials distributor in
San Diego, CA. Johnson provides support to the Greater San Diego manufacturers
of fiber reinforced and polymer products. He regularly attends composite
industry trade shows including JEC, ACMA, SME, and SAMPE. In 2008 he presented
at the Global Pultrusion Conference in Baltimore, MD. Previously, Todd spent
six years as the Business Development Manager for Ebert Composites
Corporation.
Education
B.S., Business, Management, Marketing, and Related Support Services -
the University of Colorado-Boulder's Leeds School of Business; attended Griffith
University in Queensland, Australia.
Todd Johnson
ThoughtCo and Dotdash
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publication.https://www.thoughtco.com/what-is-epoxy-resin-820372
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