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.
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 he 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.
Evacuation. The removal of entrained air from an epoxy system by vacuum.
Exotherm . The liberation of heat energy during a chemical reaction.
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.
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.
Flow. Movement of the epoxy during the curing stages before completely cured.
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.ib
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.
Hygroscopic. A property of absorbing and holding moisture.