 This page defines commonly used terms in our industry. The
terminology listed below may appear in our Technical Bulletins or may be
used in a conversation with one of our Technical Personnel while
discussing your application.Send mail to sales@deco-coat.com or call
1-888-EPOXIES if you do not find the term that you were looking for!
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Select the first letter of the word from the list above to
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command.
- A-Stage
-
- An early stage in the reaction of certain thermosetting
resins in which the material is fusible and still soluble in certain liquids.
-
- Adhesive
-
- A substance capable of holding materials together by surface
attachment. Note- Adhesive is the general term and includes among other cement, glue,
mucilage and paste. All of these terms are loosely used interchangeably.
-
- Aggregate
-
- A hard fragmented material used with an epoxy binder as a
flooring or surfacing medium. Also a coarse filler used as a core for epoxy tools.
-
- Aging
-
- The change of a material with time under defined
environmental conditions, leading to improvement or deterioration of properties.
-
- Amine
-
- Curing agent for epoxy resins that is any of a class of
ammonia derivatives. The are derived from Ammonia (NH3).
-
- Artificial Weathering
-
- The exposure of product to cyclic laboratory conditions
involving changes in temperature, relative humidity, and ultra violet radiant energy, with
or without direct water spray, in an attempt to produce changes in the material similar to
those observed after continuous outdoor exposure. Note- The laboratory exposure conditions
are usually intensified beyond those encountered in actual outdoor exposure in an attempt
to achieve an accelerated effect.
-
- ASTM
-
- American Society for Testing Materials.
- B-Stage
-
- An intermediate stage in the reaction of certain
thermosetting resins in which the material softens when heated and swells when in contact
with certain liquids, but may not entirely fuse or dissolve. The resin in an uncured
thermosetting system, is usually in this stage.
-
- Baking Temperature
-
- A temperature above 150°F.(65.6°C). Refers to curing
materials at these elevated temperatures.
-
- Bond
-
- The union of materials by adhesives.
-
- Bond Strength
-
- The unit load applied in tension, compression, flexure,
peel, impact, cleavage, or shear, required to break an adhesive assembly with failure
occurring in or near the plane of the bond. Note-The term adherence is frequently used in
place of bond strength.
-
- Brookfield Viscosimeter
-
- An instrument for measuring the viscosity of formulated
adhesives under standard conditions of temperature.
-
- Bubble
-
- Internal void or a trapped globule of air or other gas.
- C-Stage
-
- The final stage in the reaction of certain thermosetting
resins in which the material is relatively insoluble and infusible. Certain thermosetting
resins in a fully cured state are in this stage.
-
- Calorie
-
- A thermal unit. A calorie is that amount of heat required to
raise the temperature of one gram of water, one degree centigrade.
-
- Catalyst
-
- A substance which markedly speeds up the cure of an adhesive
when added in minor quantity as compared to the amounts of the primary reactants.
-
- Centigrade
-
- A scale of temperature which features 0° and 100° as
the freezing and boiling point of water respectively. To convert centigrade to Fahrenheit
multiply by 1.8 and add 32, e.g., (100° x 1.8) + 32 = 212°F.
-
- Centipoise
-
- 1/100th of a poise; (dyne-sec/cm2); a viscosity
measurement unit.
-
- Chalking
-
- Formation of a dry powdery chalk-like appearance or deposit
on the surface of a material. It is due to a breaking down of the material after being
exposed to ultraviolet light, or other weathering.
-
- Clarity
-
- Degree of clearness in a cured epoxy system.
-
- Closed-Cell Foamed
Plastic
-
- A cellular plastic in which there is a predominance of
noninterconnecting cells.
-
- Coefficient
Of Linear Thermal Expansion
-
- Once cured, a measure of the change in length of an epoxy
system over a given temperature range. It is expressed in inches per inch per degree C.
ASTM D696-44.
-
- Coefficient
Of Thermal Expansion (CTE)
-
- Change in a unit of length or volume that accompanies a unit
change in temperature.
-
- Cohesion
-
- The state in which the particles of a single substance are
held together by primary or secondary valence forces observed in the tendency of the
substance to stick to itself. As used in the adhesive field, the state in which the
particles of the adhesive (or the adhered) are held together.
-
- Compressive Modulus
-
- The ratio within the elastic limit of compressive stress to
corresponding compressive strain (deformation per original length). It is expressed in
pounds per square inch. ASTM D695-54.
-
- Compressive Strength
-
- Crushing load at the failure of a specimen divided by the
original sectional area of the specimen.
-
- Compressive
Strength, Ultimate
-
- The maximum load in pounds that can be carried per square
inch of cross section of the material under test.
-
- Conductive
-
- Having the quality of power of conducting or transmitting
heat, electricity, or static electricity.
-
- Conductivity
-
- Reciprocal of volume resistivity. Conductance of a unit cube
of any material.
-
- Cross-Link
-
- Tying together large molecules and hence changing the
physical properties of material. Cross-linking usually involves formation of three
dimensional molecular network and is customarily associated with thermosetting resins.
-
- Cure
-
- To change the physical properties of an epoxy by chemical
reaction through polymerization, usually accomplished in the presence of heat and
catalyst, alone or in combination.
-
- Cure Cycle
-
- The schedule of time periods at specified temperatures to
which a reacting thermosetting plastic or rubber composition is subjected in order to
reach certain specified properties.
-
- Curing Agent
-
- A catalytic or reactive agent which when added to resin
causes polymerization.
- Density
-
- The ratio of a substance’s mass to its volume at a
given temperature and pressure. Example-water at 25°C, 1 atmosphere of pressure =1.0
gr/cm3 = 8.35 lb. Per gallon.
-
- Dielectric Constant
-
- When electrical energy is applied in a circuit, the
insulating material of the electrical charge and releases it when the current is broken.
Capacitance is the ratio of charge absorbed to the potential (voltage applied). Dielectric
Constance is the ratio of an insulator's capacitance to that of dry air. (1.0). A
dielectric constant of 5 means an insulator will absorb 5 times more electrical energy
than air.
-
- Dielectric Strength
-
- The voltage which an insulating material can withstand
before breakdown occurs, expressed in volts per Mil.
-
- Diluent
-
- A reactive or non-reactive additive whose primary function
is to lower the viscosity and extend the material to which it was added.
-
- Dispensing Supplies
-
- Medium used to apply epoxy to pieces or units. Squeeze
bottles, syringes, needles, and meter mix equipment are all examples.
-
- Discoloration
-
- Any change from an initial color possessed by a material,
either due to environmental or internal conditions.
-
- Dissipation Factor
-
- The measure of electrical energy absorbed and lost in the
insulating material when energy is applied in a circuit. 20-3060 has a dissipation factor
of .01. This means that .01% of the energy being stored (capacitance) is lost. Dissipation
factor is the ratio of the resistive component of a capacitor to the capacitive reactance
of the capacitor. Also referred to as Loss Tangent. ASTM D150-59T.
-
- Domed
-
- Showing a symmetrical distortion of a flat or curved section
of an object so that as normally viewed. Term often used when clear "epoxy
domes" are applied to labels, pins, magnets, key tags, etc.
- Elasticity
-
- That property of materials by virtue of which they
tend to recover their original size and shape after deformation. Note-if the strain is
proportional to the applied stress, the material is said to exhibit Hookean or ideal
elasticity.
-
- Elastomer
-
- A material which at room temperature can be stretched
repeatedly to at least twice its original length and, upon immediate release of the
stress, will return with force to its approximate original length.
-
- Elongation (%)
Ability of a material to stretch or become longer.
- Encapsulation
-
- Used interchangeably with POTTING. Refers to the enclosure
of an item in a substance. Sometimes used specifically in reference to the enclosure of
capacitors or modules.
-
- Evacuation
-
- The removal of entrained air from an epoxy system by vacuum.
Also referred to as degassing.
-
- Exotherm
-
- The liberation of heat energy during a chemical reaction.
Exotherm is increased in large masses.
-
- Extender
-
- An available or relatively inexpensive compatible material
which can be added to a more valuable substance so as to increase the amount of material
in useful form. The use of extenders may involve adulteration under some conditions.
- Failure, Adhesive
-
- The failure at the bond line between substrates and an
adhesive; the adhesive separating entirely from the substrate.
-
- Failure, Cohesive
-
- Failure within the adhesive under a stress, resulting in a
broken bond with all adhered surfaces still covered with adhesive.
-
- Failure, Substrate
-
- The failure of the substrate material itself, upon
subjecting bonded adhered surfaces to a stress.
-
- Filler
-
- A substance, often inert, added to a system to improve
properties and/or decrease cost.
-
- Fisheyeib
-
- Small globular mass which has not blended completely into
the surrounding material and is particularly evident in a transparent or translucent
material.
-
- Flame Retardance
-
- The ability of an epoxy system to resist combustion or
burning. Some materials tend to extinguish themselves when subjected to a flame. Such
materials are classified as self-extinguishing. ASTM D790-63.
-
- Flash Point
-
- The temperature at which the material gives off flammable
vapor in sufficient quantity to ignite momentarily on the application of a flame under
specified conditions.
-
- Flexural Modulus
-
- The ratio, within the elastic limit, of flexural stress to
the corresponding strain. It is expressed in pounds per square inch. ASTM D790-63.
-
- Flexural Strength
-
- Ability of a material to withstand failure due to bending.
-
- Flow
-
- Movement of the epoxy during the curing stages before
completely cured.
-
- Forced Drying
Temperatures
-
- A temperature between room temperature and 150°F.(65°C).
-
- Fusible
-
- Capable of being melted or fused together by melting.
- Gallon, U.S
-
- A volume equal to 231 cubic inches measured at 25°C.
(77°F).
-
- Gardner Color Scale
-
- A system of color standards based upon stable solutions of
ferric chloride used in the evaluation of resins, lacquers, oils and varnishes. The
Gardner Scale can be correlated roughly with other color standards such as FAC, ASTM, NPA
and Lovibond.
-
- Gel
-
- The initial jelly-like solid phase that develops during the
transition from a liquid to a solid. Note - In this state the epoxy is soft, flexible, and
has no strength.
-
- Glass Transition
Temperature (Tg)
-
- Approximate midpoint of the temperature range over which a
material undergoes a phase change from brittle to rubbery or vice versa.
-
- Glossib
-
- That property of the cured epoxy or any other material which
causes it to reflect light.
- Hardener
-
- A substance or mixture of substances added to an epoxy resin
to promote or control the curing reaction by taking part in it.
-
- Heat
Distortion (Deflection) Temperature
-
- The temperature at which a material softens enough to
distort under a given load. It is not usually considered to be beyond the maximum usable
temperature, but is an indication of the maximum usable temperature when the material is
load bearing at a given load. As the load decreases, the maximum usable temperature will
increase.
-
- Heat Sink
-
- Any device that absorbs and draws off heat from a hot
object, thereby neutralizing the extreme temperature.
-
- Humidity (Absolute)
-
- The amount of moisture present in the atmosphere expressed
in grams per cubic meter.
-
- Humidity (Relative)
-
- The ratio of the amount of moisture contained in the
atmosphere to the amount of moisture that can be carried in the atmosphere at a given
temperature. Relative humidity is expressed in percent, e.g., 75% R.H. at a given
temperature means that the air is 75% saturated with moisture.
-
- Hygroscopic
-
- A property of absorbing and holding moisture.
- Impregnate
-
- To fill the voids and spaces of an electrical unit with a
compound. (This does not imply complete fill or complete coating of the surfaces by a
hole-free film).
-
- Insulation Resistance
-
- The ratio of the direct voltage applied to electrodes in
contact with an epoxy system to the total current between them. It is dependent upon both
the volume and surface resistance of the epoxy systems. ASTM D257-61.
-
- Intermittent
Operating Or Service Temperature
-
- The temperature to which the epoxy system can be subjected
for short periods of time without degradation of its properties.
-
- Izod Impact Strength
-
- A measure of the brittleness of a material. Brittle
materials will have low izod impact values (.15 for example). Tough materials will have
high izod impact strengths (.60 for example).
- (empty)
- (empty)
- (empty)
- Maximum Service
Temperature
-
- Highest recommended continuous use temperature based upon
thermal endurance and historical data.
-
- Modifier
-
- Any ingredient added to an epoxy formulation that changes
its properties.
-
- Moisture Resistance
-
- Having some resistance to high humidity. A moisture
resistant adhesive will not be easily affected by moisture. Will not easily change its
chemical and physical properties due to moisture. Should not be confused with "water
proof."
- (empty)
- OHM Unit
-
- Unit of electrical resistance. Resistance of a circuit in
which a potential difference of one volt produces a current of one ampere.
-
- Opaque
-
- Any material is opaque if no light can be transmitted
through it.
-
- Operating Or
Service Temperature
-
- The temperature at which an epoxy system can operate
continuously without degradation of its properties.
-
- Orange-Peel
-
- Uneven surface somewhat resembling an orange peel.
- Pigment
-
- The fine solid particle, usually inorganic, used in the
preparation of colored products, and substantially insoluble in the vehicle. In contrast,
a dye is soluble.
- Pit
-
- Small regular or irregular crater in a surface, usually with
its width approximately of the same order of magnitude as its depth.
-
- Pot Life
-
- The length of working time of a two component reactive
system from the time of the addition of the curing agent in a specific mass (i.e. 100
grams). It is expressed in minutes.
-
- Potting
-
- Similar to encapsulating, except that steps are taken to
insure complete penetration of all the voids in the object before the resin polymerizes.
-
- P.S.I.
-
- Pounds per square inch; a unit measure of pressure.
- (empty)
- Resistivity
-
- The ability of a material to resist passage of electrical
current either through its bulk or on a surface. The unit of volume resistivity is the
ohm-cm, of surface resistivity, the ohm.
- Set
-
- To convert an epoxy into a fixed or hardened state by
chemical or physical action through polymerization.
-
- Shear Strength
-
- The shear force required to break a specimen divided by its
cross-sectional area; the force being applied parallel to the cross-sectional area.
-
- Shore A Hardness
-
- The reading of a material's hardness on a durometer, the
scale of which is 0-100, used on elastomers and other flexible materials. Consists of a
pin point depression into the material, the material being at least 100 mils thick. A
Shore A reading of 80 equal a Shore D reading of 30.
-
- Shore D Hardness
-
- The reading of a material's hardness on a durometer similar
to the Shore A durometer, the scale of which 0-100, used on rigid and semi-rigid
materials. Consist of a pin point depression into the material. Both the Shore A and Shore
D instruments are made by the Shore Instrument Manufacturing Company, Inc., Jamaica, NY.
-
- Shrinkage
-
- The decrease in volume, or contraction, of a material by the
escape of any volatile substance, or by a chemical or physical change in the material.
-
- Softening Range
-
- The range of temperature in which a thermoplastic changes
from a rigid to a soft state.
-
- Specific Gravity
-
- The ratio of the weight of any volume of a mass or substance
to the weight of an equal volume of water at given temperature. The specific gravity of a
substance times the density of water equals the density of the substance.
-
- Storage life
-
- The period of time during which a packaged epoxy or curing
agent can be stored under specific temperature conditions and remain stable for use.
Sometimes called shelf life.
-
- Stress
-
- An applied force or pressure, as tension or shear, exerted
on a body which produces a resultant strain on the material. The ability of material to
withstand a stress depends on the strength of its cohesive force or molecular resistance.
-
- Stripper
-
- A compound used to remove undesirable foreign material from
a surface. Such compounds should possess good penetration, rinse freely and not attack the
substrate.
-
- Stripping
-
- The removal of undesirable substance from a surface by
abrasive or chemical action.
-
- Substrate
-
- A material upon the surface of which an epoxy is spread for
any purpose, such as bonding or coating.
-
- Surface Resistivity
-
- The resistance to a current flow along the surface of an
insulator material. Measure in ohms-cm.
-
- Surface Tension
-
- The property of a liquid which causes the surface to pull
into the smallest area for a maximum volume, hence, drops are spherical. The fact that
water drops on a wax surface do not spread out due to surface tension. If a wetting agent
were to be added to the water the round droplet would spread out into a film because of
the lowered surface tension.
- Temperature, Curing
-
- The temperature to which an adhesive or an assembly is
subjected to cure the adhesive. Note-The temperature attained by the adhesive in the
process of setting it may differ from the temperature of the atmosphere surrounding the
assembly.
-
- Tensile Strength
-
- The pulling force necessary to break a given specimen
divided by the cross sectional area. Units given in lbs./in/2 (P.S.I.).
It measures the resistance of a material to stretching without rupture. Normally is not
used with reference to elastic materials which recover after elongation.
-
- Thermal Conductivity
-
- A measure of how rapidly heat is conducted through a
material.
-
- Thermal Shock
Resistance
-
- The ability of a cured system to resist cracking or crazing
under conditions of rapid and continuous thermal change. The 1/4 inch Olyphant Washer test
is cycled over a temperature range of -55°C to +125°C, this
temperature is normally used as the test condition unless otherwise stated.
-
- Thermosetting
-
- Describes the property of an epoxy, to set or become rigid
and non-meltable when heated with or without pressure.
-
- Thixotropy
-
- False body. The property of a paste or fluid to thicken or
set up to a paste or semi-gel when allowed to stand. Agitation breaks it down but further
standing will again permit a viscosity rise.
-
- Time, Curing
-
- The period of time during which an assembly or part may be
subjected to heat or pressure, to cure the epoxy. It is the time between the addition of
curing agent to the resin, and completed polymerization.
- (empty)
- Viscosity
-
- The property of resistance to flow exhibited within the body
of a fluid. Usually measured in centipoise.
-
- 1 cps = Water
- 400 cps = #10 Motor Oil
- 1,000 cps = Castor Oil
- 3,500 cps = Karo Syrup
- 25,000 cps = Hersheys Chocolate Syrup
-
- Volume Resistivity
-
- The ratio of the electrical resistance through a cross
section A divided by the length through which the current flows. Measured in ohms-cm.
-
- Volume Shrinkage (%)
-
- Amount of dimensional change during cure.
- Water Absorption (%)
-
- % by weight water absorbed by material in 24 Hours @ RT
-
- Waviness, Surface
-
- Wave-like unevenness, or out-of-plane in a surface.
-
- Wetting
-
- The thorough impregnation of a material by a liquid. The
more viscous a fluid, and the higher its surface tension, the more difficult it is for the
liquid to "wet" materials. Certain additives, for example, water softeners,
reduce surface tension, or viscosity and improve wetting properties, allowing the material
to flow out more.
-
- Working life
-
- The period of time during which an epoxy after mixing with a
curing agent, remains workable and suitable for use.
- (empty)
- Yield Strength
-
- The load in pounds per square inch where the material under
test begins to change dimensions and will not completely recover when the load is
removed. Yield strength will normally be lower than ultimate strength. Generally speaking,
the more rigid a material is, the closer will be yield and ultimate strengths.
Furthermore, the more resilient a material is, the greater the spread between yield and
ultimate strengths.
- (empty)
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