| GLOSSARY |

Abhesion
Lack of adhesion, easy release from substrates

Acetoxy Cure System
A tin catalyzed moisture cure system which liberates an acetic acid/ vinegar odor by-product upon curing.

Adhesive
Displaying self bonding properties without primers

Addition Cure System
Reaction between a vinyl terminated siloxane and a polyfunctional silicon hydride with a catalyst.

Si-H + CH2 = CHSi ------------> SiCH2CH2Si

Application Rate
Used to measure the flow of RTV sealants from a semco tube. Material is extruded from a semco tube at 90 psi through a standard orifice. Given in grams per minute.

By-Products
The evolved reaction materials of a condensation cure silicone with moisture. These typically generate the odor found when silicones cure.

Condensation Cure System
Reaction between silanol terminated polydimethylsiloxane and multifunctional crosslinker with a catalyst.

Si-OH + AcOSi ---------- > Si-O-Si + AcOH

Curing
Silicone liquids or pastes harden to a rubber elastomer

Cure Time
The time required to convert the silicone sealant to cured rubber. Example: 24 hours for 1/8” diameter bead at 77° F and 50% relative humidity.

Dimethicone
Trimethyl terminated siloxane fluid

Durometer
Resistance to indentation. Measure of the crosslink density of a rubber sample.

Elongation – (elongation at break)
The ability of the test piece to be stretched without breaking. Given in % of original dimension @ maximum elongation.

Encapsulation
The complete surrounding of an electronic component or complex of components with a coating of an insulative material. The purpose is to protect the component from adverse environmental conditions.

Fast Cure
An order of magnitude faster than typical – Most R.T. cures are slow

FIP
Form in place gasketing

Gel Time
The period of time in which as liquid material becomes too viscous to flow or be tooled

Heat Cured
1 or 2 part product that Vulcanizes into a hard, cured product upon exposure to heat

Instant Cure
Heat accelerated room temperature cure within 1 minute

Lamination
Fully enclosing an adhesive between two sheets disallowing exposure of the surface preventing offgas and surface cure. Condensation cured silicones require exposure to air for full cure.

Modulus
The amount of force per square inch to stretch a test piece to a given elongation.
Typically measured @ 100% elongation.

Neutral Cure
A condensation cure system which liberates no corrosive (to metals) by-products upon curing. Alkoxy/Alcohol cure systems are neutral cure.

One-Part
A ready-to-use silicone material that does not require mixing with a catalyst or other additive to form a durable rubber or adhesive.

Oxime Cure System
A tin catalyzed moisture cure system which liberates an alcohol methylethyl ketoxime byproduct upon curing. This byproduct smells like latex paint.

PDMS
Poly Dimethyl Siloxanes (see siloxane)

Peelable
Displaying no adhesion for easy removal

Pot Life
The amount of time available between the moment that a catalyst is stirred into a base material and the approximate moment that it becomes too thick to apply in the recommended manner.

Potting Material
An electrically insulative, moisture resistant material, supplied in a liquid or putty-like form and used as a protective coating on sensitive areas of electrical and electronic equipment.

Pourable
Self- leveling liquid

Rheology
The study of the deformation and flow of materials, in terms of stress, strain and time.

R.T.
Room temperature cure

R.T.V.
Room temperature vulcanization (curing without heat)

Self-Leveling
A high flow, syrup-like condition, unlike thixotropic

Silane
A highly reactive molecule having a Silicon atom as the central unit. Typically functionalized and used as crosslinkers and adhesion promoters.

Silicone Plasticizers
Trimethyl terminated siloxane fluid

Silicone Rubber
A rubber like polymer prepared from certain silicones. It maintains its elasticity and electrical properties over a wide range of temperatures and is widely used in sealants, gaskets, insulation, tapes, etc.

Siloxane Fluids
Polymers having a regular alternating silicon and oxygen central atoms, typically having pendant dimethyl functionality, these polymers can be functionalized interchain and at chain terminus for a wide range of applications.

Simethicone
Trimethyl terminated siloxane fluid

Skin-Over
The formation of an integral skin over the surface of a quantity of sealant.

Specific Gravity
The ratio of the weight of any volume of a material to the weight of an equal volume of water.

Tack-Free Time
The time it takes for a sealant to cure to a point where none of the material will stick to your finger.

Tear Resistance
Resistance to growth of a nick or cut in a test piece when tension is applied. Given in pounds per inch or Newton per millimeter.

Tensile Strength (tensile at break)
The amount of force required to break a test piece. Given in pounds per square inch (PSI) or Newton per square millimeter (N/mm2).

Two-Part
A silicone material which must be mixed with a catalyst or other additive to form a durable rubber.

Thixotropic
Non-slump or sag property, no flow without pressure

Uncured
A silicone material which has not vulcanized or formed a durable rubber.

Viscosity
The measurement of a fluid’s resistance to relative motion within itself. The viscous property of a fluid. Usually considered to be the relative thickness or thinness of a fluid as compared to the thickness (thinness) of water

Volatiles
Low molecular weight silicone materials that can become airborne. Found in certain silicone polymers.

Work Time
The period of time which a silicone material may be “worked” before skin over and curing begins.

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