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Glossary

Permabond Terms Glossary

A

Accelerator, Activator – Terms used to describe the materials which initiate the polymerization needed to cure anaerobic, cyanoacrylate and modified acrylic adhesives.

Activator – Activators used with Anaerobics often called Anaerobic Surface Conditioners are used to accelerate cure on passive metals or allow cure with non-metallic surfaces.  They are also used to increase the maximum gap the anaerobic adhesive or sealant will cure through.

Acrylic Adhesive -Acrylic adhesives are adhesives that are made of acrylic or methacrylic polymers.The most common types of acrylic adhesives are two-component acrylic adhesives and no mix surface activated acrylic adhesives. Both are structural adhesives.

Acrylic Glue – Acrylic glue is a casual term for acrylic adhesive which are adhesives that are made of acrylic or methacrylic polymers.  The most common types of acrylic adhesives are two-component acrylic adhesives and no mix surface activated acrylic adhesives. Both are structural adhesives.

Adherend (or Substrate) – Material which is being joined or bonded.

Adhesion Chemistry – The science and study of the state in which two components join by either interlocking action or intermolecular forces at the adhesion junction.

Adhesive – Substance for bonding, sticking or holding things together.

Adhesive, Acrylic – Acrylic adhesives are adhesives that are made of acrylic or methacrylic polymers. The most common types of acrylic adhesives are two-component acrylic adhesives and no mix surface activated acrylic adhesives. Both are structural adhesives.  They offer fast fixture, cure at room temperature, and form strong bonds to many materials including glass, metal, plastics, and composites.

Adhesive, Anaerobic – An adhesive which only cures when air is excluded, and metal ions are present, and metal ions are present.  Uses include threadlockers, retaining compounds, form in place gaskets, and thread sealants.

Adhesive, Cyanoacrylate – Group of adhesives which show “instant” cure properties and bond to a wide variety of substrates. Cure is by contact with alkaline materials. Weakly alkaline materials, such as water, cause the cure to start. Cyanoacrylate adhesives are commonly referred to as super glue, instant adhesive, crazy glue, loca glue or ca glue.

Aging, Heat – Artificial “aging” of adhesive by exposing to elevated temperatures for long periods.

Ambient Conditions – Temperature, humidity, sunlight, etc. which exist in the area surrounding the bond, normally room temperature, atmospheric pressure, daylight, etc.

Anaerobic Adhesive – An adhesive which only cures when air is excluded.

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B

Bead on Bead Acrylic Adhesive– Bead on Bead acrylic adhesives are two-component acrylic adhesives which are not mixed via a static mix nozzle but applied as a bead of part A followed by a bead of part B on top of the bead of part A.  Sufficient mixing occurs when the components are assembled to initiate cure.  Bead on Bead acrylic adhesive provides fast fixture and cure at room temperature.

Bond– Interface of the adhesive and the substrate.

Breakaway Torque – Measure of force needed to initiate movement of an unseated fastener in a loosening direction.

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C

CA Glue – CA glue is a common term referring to cyanoacrylate adhesive.

Coefficient of Thermal Expansion or CtE relates the change of a material’s size with temperature change. Why is it relevant? Over time and thermal cycles, bonds between two materials with very different CtE’s can cause the adhesive to crack. Cracks in the adhesive will alter the insulating or conducting strength.  The higher the CtE number, the more ‘give and take’ the adhesive has, and the less likely cracks will occur.

Cohesive Failure – Condition of bond failure in which the adhesive falls apart.

Conditions, Ambient – Temperature, humidity, sunlight, etc. which exist in the area surrounding the bond, normally room temperature, atmospheric pressure, daylight, etc.

Cure Speed – Time needed for an adhesive to reach full strength.  See curing time.

Curing Time – Curing time can be reported several ways.  Terms like handling time, skin over time, fixture speed, pot life, working strength, are all terms that refer to points along the path of full cure or full strength.

Cyanoacrylate Adhesive – Group of adhesives which show “instant” cure properties and bond to a wide variety of substrates. Cure is by contact with alkaline materials. Weakly alkaline materials such as water, cause the cure to start. Cyanoacrylate adhesives are commonly referred to as super glue, instant adhesive, crazy glue, loca glue or ca glue.

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E

Electrical Conductivity – Electrical conductivity is a measure of a substance’s ability to conduct electrical current.

Epoxy Adhesive – An adhesive made from synthetic thermosetting polymers which contain epoxide groups.  Epoxy adhesives are available in one component which is cured with heat and two component which can be cured at room temperature or elevated temperature.

Epoxy Glue – See epoxy adhesive.

Epoxy 1 part – (One component epoxy or 1K epoxy) – One component epoxy adhesives are adhesives made from thermosetting polymers which contain epoxide groups and cure at elevated temperature.

Epoxy  2 Part – (Two part epoxy, 2K epoxy, 2 part epoxy) – 2 part epoxy adhesives are adhesives made from thermosetting polymers which contain epoxy resin and hardener which cure when mixed together.  These adhesives can cure at room temperature. However, elevated temperature curing can increase cure rate – and for some products enhance cured properties such as temperature resistance

Epoxy Food Grade – Food grade epoxy or food safe epoxy are general terms.  In the US and many other countries, the US Food and Drug Administration (FDA) uses Title 21 Code of Federal Regulations CFR 175 subsection 105 is Adhesives and subsection 300 is Resinous and polymeric coatings.  Each section contains a list of raw materials that are acceptable for use in food contact applications of adhesive.  Permabond has several epoxy adhesives that were formulated with FDA approved raw materials.

Epoxy Paste – Epoxy paste is a common term for high viscosity epoxy adhesives which are adhesives made from synthetic thermosetting polymers which contain epoxide groups.  Epoxy adhesives are available as one component, which is cured with heat, and two component which can be cured at room temperature or elevated temperature.  Sometimes the word paste is used to describe the viscosity of the epoxy.

Epoxy Putty – Epoxy putty is a common term for very high viscosity epoxy adhesives.  Epoxy adhesives are adhesives made from synthetic thermosetting polymers which contain epoxide groups.  Epoxy adhesives are available as one component, which is cured with heat, and two component which can be cured at room temperature or elevated temperature.

Exotherm – Exothermic materials give off heat when they cure. When large quantities cure all at one time, the amount of heat given off (the exotherm) can be high enough to melt plastic containers.

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F

Failure, Cohesive – Condition of bond failure in which the adhesive falls apart.

Failure, Substrate – Condition of bond failure in which the substrate falls apart. The cohesive strength of the adhesive and the adhesive forces between the adhesive and substrate exceed the internal strength of the material being bonded.

Fill, Gap – Ability of an adhesive to fill the space between substrates and hold the substrates in place.

FIP Gasket (Form in Place Gasket) – Are liquid or semi-liquid adhesive/sealants which create a gasket in situ as opposed to sourcing the correct size and shape gasket.  Anaerobic form-in-place gaskets are for use on metals.  Liquid gasketing adhesives provide 100% contact between the metal parts allowing reduced tolerances to save on surface finish machining which reduces costs and increases production rates.

Fixture Time – Time needed for adhesive to reach sufficient strength to allow pieces to be handled and moved.

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G

Gap Fill – Ability of an adhesive to fill the space between substrates and hold the substrates in place.

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H

Heat Aging – Strength measured at room temperature after some period of aging at elevated temperature.

Heat Cure Epoxy – One component epoxy adhesives are adhesives made from thermosetting polymers which contain epoxide groups and cure at elevated temperature.

Heat Resistant Epoxy – An epoxy adhesive that forms bonds that resist higher than average temperature.  Many 1 part epoxy adhesives resist  355°F (180°C) and standard 2 part epoxy resist 175-212°F (800-100°C).  Heat resistance above that standard range is considered high-temperature resistance.

High Temperature Epoxy – See Heat Resistant Epoxy

Hot Strength – Strength measured at elevated temperature.

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I

Impact Strength – Resistance to sharp, intense blows or force.

Industrial Adhesive – (or industrial glue) is an adhesive that is not packaged for consumer use.

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L

Lap Shear – Test to measure resistance to shear stress by bonding the ends of flat bars in an overlapping position.

Locking Torque – Test designed to measure breakaway and prevailing torque of a threaded piece coated with thread locking adhesive.

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M

Metal Adhesive –Metal glue or adhesive is a term that refers to a product that is intended for use on metal.  Many adhesive types bond very well to metal including structural acrylic, epoxy, anaerobic, and cyanoacrylate.  See how to glue metal.

Methyl Methacrylate Adhesive – MMA – MMAs are acrylic adhesives that are made of methacrylic polymers.  MMA adhesives are either two component adhesives which are mixed via static mixer and will mix adequately when the two components are joined.  MMA adhesives are also available as surface activated adhesives in which an initiator is applied to one surface and the resin to the other.  Cure is initiated upon joining.

Monomer – Chemical which can be caused to join and form polymers.

MRO – Maintenance, repair, and overhaul.

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O

OEM – Original equipment manufacturer.

Open Time – Time during which the adhesive remains active without curing after being applied to the substrate.

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P

pH – Measure of acidity. A pH of 1 would be very acidic. A pH of 7 is neutral. A pH of 10 is very alkaline.

Pipe sealant (Thread sealant) – Anaerobic adhesives and sealants used to seal threaded metal pipe work, to lock against loosening, and prevent corrosion.

Plastic adhesive – plastic glue refers to an adhesive that will bond well to plastic.  Many adhesive types bond plastics including acrylics, epoxies, cyanoacrylates and UV curable adhesives. See how to glue plastic

Polymers – Substance made up of many units such as polyethylene, polystyrene, etc.

Prevailing Torque – Measurement of average force needed to provide continuing movement, after unseating, through first full turn.

Primer, Surface – A surface primer is a coating that changes the character of a surface so that an adhesive or coating will adhere to it more effectively.

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R

Retaining Compound (Retainer) – Anaerobic retaining compounds are used to permanently secured non-threaded, metal, cylindrical parts onto shafts or into housings.  For example, bearings.  Anaerobic retaining compounds provide 100% surface to surface contact wherein mechanical joining techniques provide only 20% contact.  The resulting increase in surface area allows for greater load carrying capacity.

Rheology – Special consideration of viscosity. Considers the effect of such things as stickiness and sensitivity to shear on viscosity.

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S

Seal – To block entrance from one side to another.  When choosing an adhesive or sealant, it is important to note not only the substrates but also the material to be sealed out.  What type of gasses or fluids etc…

Shear, Lap – Test to measure resistance to shear stress by bonding the ends of flat bars in an overlapping position.

Shear, Static – Test to measure resistance to shear stress by bonding a pin within a collar or ring.

Shore Hardness – A Durometer gauge is used to measure how soft or hard an adhesive is.  The result is reported with the gauge indication.  The A scale is used for soft adhesives and the D scale for more rigid.

Skin Over Time – The time required before the surface of the adhesive is dry to the touch.  Further cure may be necessary to cure through the thickness of the adhesive.

Speed, Cure – Time needed for an adhesive to reach full strength.

Static Shear – Test to measure resistance to shear stress by bonding a pin within a collar or ring.

Strength, Hot – Strength measured at elevated temperature.

Strength, Impact – Resistance to sharp, intense blows or force.

Structural Acrylic Adhesive – Structural acrylic adhesives are acrylic adhesives that form bonds that bear a structural load.

Substrate – Material which is being joined or bonded.

Substrate Failure – Condition of bond failure in which the substrate falls apart. The cohesive strength of the adhesive and the adhesive forces between the adhesive and substrate exceed the internal strength of the material being bonded.

Surface Activated Acrylic Adhesive – Surface activated acrylic adhesives are generally two component acrylic adhesives in which an activator or initiator is applied to one surface and the acrylic resin to the other surface.  Upon joining cure is initiated.  In some cases, single component acrylic adhesives are activated by metal surfaces.  Acrylic adhesives are adhesives that are made of acrylic or methacrylic polymers.

Surface Primer – A surface primer is a coating that changes the character of a surface so that an adhesive or coating will adhere to it more effectively.

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T

Thermoplastic – A thermoplastic material will soften when exposed to high temperature. It literally becomes plastic when heated. Usually, removing the heat restores the original strength.

Thermoset – Products that will only cure when exposed to heat are described as thermoset resins. After they are cured, subsequent heat exposure will have little or no effect on the properties of the cured resin.

Thread Sealant – Anaerobic adhesives and sealants used to seal threaded metal pipe work, to lock against loosening, and prevent corrosion.

Threadlocker or (Thread locker) – Threadlockers are anaerobic adhesives and sealants used to lock metal fasteners against loosening, prevent corrosion, and provide a seal.  Note other adhesives/sealants can be used to lock threads on nonmetal fasteners.

Thixotropy – Term which describes the flow character of a liquid or paste. Liquids that are thixotropic flow under shear but flow less when the shear is removed. Best example is ketchup.

Time, Fixture – Time needed for adhesive to reach sufficient strength to allow pieces to be handled and moved.

Time, Open – Time during which the adhesive remains active without curing after being applied to the substrate.

Torque, Breakaway – Measure of force needed to initiate movement of an unseated fastener in a loosening direction.

Torque, Locking – Test designed to measure breakaway and prevailing torque of a threaded piece coated with thread locking adhesive.

Torque, Prevailing – Measurement of average force needed to provide continuing movement, after unseating, through first full turn.

Toughened Acrylic Adhesive – Toughened acrylic adhesives is another term for structural acrylic adhesives which are acrylic adhesives that form bonds that bear a structural load.  Acrylic adhesives are adhesives that are made of acrylic or methacrylic polymers.  The most common types of acrylic adhesives are two-component acrylic adhesives and no mix surface activated acrylic adhesives.

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V

Viscosity – Measure of fluid thickness or resistance to flow expressed in poise or centipoise. Water is one centipoise. Thicker fluids have higher numbers. 30 weight oil has a viscosity of 400 centipoise (cps).

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