Description

Gel elastomers are highly viscoelastic polymer gels that have excellent shock absorption and damping characteristics. Typically, they are produced via a two-part casting system. Viscosity, hardness, tensile strength, processing temperature, cure time, and pot life are key properties to consider.

Types

The GlobalSpec SpecSearch Database contains these types of gel elastomers.

Composite gels are types of gel elastomers made from two or more constituent materials with significantly different physical or chemical properties. One of these constituents is generally a strengthening phase, reinforcement fibers, toughening phase, or other specialty fillers that provide unique properties.

Thermoplastic gels are polymers that turn to liquid when heated and turn solid when cooled. They can be repeatedly remelted and remolded, allowing parts and scraps to be reprocessed. In most cases they are also very recyclable. Oil gels are used as a low-cost ballistic gels, shock mountings, cushioning, and hand grips for bicycles and motorcycles.

Thermosets or thermosetting plastics are polymer materials that have been irreversibly cured. They are generally stronger than thermoplastics due to the polymer cross-linking and are better suited for high-temperature applications (below their decomposition points). They tend to be more brittle than thermoplastics and many cannot be recycled due to irreversibility.

Polyurethane gel is a class of very soft resin material used in computer wrist rests, bike seating, upholstery, and shoe insoles. Softness is easily customizable based on composite mixing ratios. These gel elastomers last longer than materials such as thickened glycerin pouch fillers. Unlike some other gel materials, they also contract within the same space.

Silicone gels are two-component systems with a 1:1 mix ratio of silicone and another component that cure to a very soft consistency. They provide excellent moisture protection and offer strong resistance to thermal and mechanical shock. Because they also provide protection from vibration, silicone gel elastomers are often used to protect extremely sensitive components. Like other gel elastomers, they should be stored unopened in their original container.

Properties

Important properties to consider when selecting a gel elastomer are its use temperature, coefficient of thermal expansion, and electrical resistivity.

Use temperature is the allowable temperature range in which the gel can operate effectively which determines what environments an elastomer can be used in. The coefficient of thermal expansion is a measure of the tendency of the gel to change in volume in response to temperature, which could limit size restraints under certain operating temperatures. The electrical resistivity is a gels ability to resist the flow of electricity, which determines its usefulness either as a medium or protector against current flow.