Intro to Adhesive Properties 130

acrylic adhesive

A type of structural adhesive made from acrylic, a transparent polymer that is tough and flexible. Acrylic adhesives set rapidly and are very strong due to heavy cross-linking.

additive

A substance added to another substance or material to change or improve performance.

adhesive

A substance used to join two or more materials. Adhesives have a wide range of properties which make them suitable for a variety of manufacturing situations.

adhesive strength

The ability of an adhesive to stick to a surface. Adhesive strength allows an adhesive to bond two surfaces together.

anaerobic adhesive

A type of structural adhesive that can cure and harden only in an oxygen-free environment.

blooming

The condensation of evaporated adhesive on a part. Blooming occurs most often with cyanoacrylates.

brittle

A material's unwillingness to be drawn, stretched, or formed. Brittle materials tend to break or crack if subjected to these forces.

centipoise

A unit of measurement that describes viscosity, or a liquid's resistance to flow. A centipoise is one/one hundredth of a poise.

chemical properties

The properties that describe a material's ability to withstand deterioration by solvents, chemicals, or water on the chemical level.

cleavage strength

A material's ability to resist forces that can pull it apart by separating two rigid surfaces. In general, adhesives have low cleavage strength.

cohesive strength

The ability of adhesive molecules to remain connected and not tear apart. Adhesives with low cohesive strength bond to a surface, but still cannot hold the joint together.

color

The quality that determines an adhesive's hue, lightness, or saturation. Color is determined by light reflected by the adhesive.

creep

The deformation of a material that occurs over time due to the presence of a constant load.

creep strength

The ability of an adhesive to withstand a constant weight or force over an extended period of time.

cross-link

To develop primary bonds between polymer molecules.

cure

To cause a material to bond by permanently cross-linking its molecules. Adhesives cure as they solidify.

cure time

The length of time needed for an adhesive to cure fully. If an adhesive is not given enough time to cure, the bond will fail.

curing

The process in which an adhesive undergoes a molecular reaction and becomes a solid. Curing may require light, heat, or the passage of a specific amount of time.

curing accelerator

A type of additive that increases the speed of curing in an adhesive.

cyanoacrylate

A type of synthetic adhesive made from acrylic, a manufactured polymer. Cyanoacrylates bond with surfaces very quickly.

damping

The ability of a material to resist deformation through vibration.

elastic

Capable of resuming original shape after experiencing temporary deformation. Solid materials can be elastic but liquids and gases cannot.

elasticity

The measure of a material's ability to reshape itself after it has been stretched or deformed. A rubber band has high elasticity.

electrical conductivity

A material's ability to act as a medium for conveying electricity.

epoxy adhesive

A type of structural adhesive made from epoxy, a manufactured polymer. Epoxy adhesives form strong resilient bonds with a variety of surfaces.

flammability

The ability or tendency to ignite or burn when exposed to an open flame.

glass transition temperature

The temperature at which the adhesive physically changes from a solid to a liquid or from a liquid to a solid.

green strength

The ability of an adhesive to be handled before it has completely cured. Green strength allows a part to continue moving through the assembly line while the adhesive cures.

hardness

A material's ability to resist penetration, indentation, or scratching.

hydrolysis

The decomposition of an adhesive due to extensive water exposure. Hydrolysis negatively affects the properties of an adhesive.

load

The overall force applied to a material or structure.

mechanical properties

The characteristics of a material that determine how it reacts when it is subjected to some type of force that attempts to stretch, dent, scratch, or break it.

metal ion

An atom in a metal compound that has an electrical charge. Metal ions can cause adhesives to cure.

moisture

Water that is condensed as droplets. Moisture can affect the properties of adhesives.

nonmechanical properties

The characteristics of a material that determine how it reacts to forces that are not mechanical. Chemical and physical properties are examples of nonmechanical properties.

one-part curing

A type of adhesive that does not need to be mixed with another material in order to cure.

part blueprint

A document that contains the instructions necessary for the application of an adhesive to a part.

peel strength

A material's ability to resist forces that can pull it apart by separating a flexible surface from a rigid surface. In general, adhesives have low peel strength.

physical properties

The set of properties that describe a material's ability to melt, conduct heat and electricity, and expand or shrink.

properties

The essential characteristics of a material that distinguish it from other materials.

shear strength

A material's ability to resist forces that can cause the internal structure of the material to slide against itself. In general, adhesives have high shear strength.

shelf life

The length of time an adhesive can remain in storage without losing its properties.

shrink

To reduce in size. Adhesives shrink as they cure and solidify.

silicone adhesive

A type of structural adhesive made from silicone, a water repellent material that contains the silicon atom. Silicone adhesives will set as soon as they contact air.

strain

The physical change that takes place in an object when it is under stress. Strain is a measurement of stress.

strength

The ability of a material to resist forces that attempt to break or deform it.

stress

A force that attempts to deform an object. The stronger the stress, the more a solid will physically change.

tackifier

A type of additive that increases the tackiness of an adhesive.

tackiness

The ability of an adhesive to form an immediate bond with a surface upon contact.

temperature

A measurement of the degree of heat within a material.

temperature resistance

The ability of an adhesive to work at very high or very low temperatures.

tensile strength

A material's ability to resist forces that attempt to stretch it or pull it apart. In general, adhesives have high tensile strength.

two-part curing

A type of adhesive that must be mixed with a curing accelerator in order to cure.

urethane adhesive

A type of structural adhesive made from urethane, a manufactured polymer known for its strength and versatility. Urethane adhesives form flexible joints.

viscoelastic

Having both viscous and elastic qualities. Adhesives are viscoelastic materials.

viscoelasticity

A material's ability to have both viscous and elastic qualities. Adhesives are viscoelastic.

viscosity

A liquid's resistance to flow. The higher the viscosity, the more the liquid resists flowing.

viscous

Having the ability to resist flow. Honey is a good example of a viscous liquid, while water is not.

working life

The time period during which an adhesive must be used after its container has been opened or, in the case of two-part curing adhesives, after it has been mixed.