Elastomer

Description

The most frequent elastomers are the natural rubber collected in the plantations of hévéas and its synthetic equivalent. The made up elastomers like the tires are often a mixture of natural rubber and synthetic rubber.

Rubber (natural) remained a long time the only known elastomer. The term of rubber is a usual elastomer synonym.

The elastomers contain from 50 to polymer 60%. The remainder is composed of loads, agents of Vulcanization, Accélérateur S, products delaying ageing and other additives which make it possible to modify the Raw material, in order to fulfill the requirements of a definite application.

What makes elastomers special, it is their capacity of elastic collisions the such bounce and the elastic stretching, which enables them to regain their initial shape after stretching. This special characteristic is acquired by the tangle of long polymeric chains.

Mechanical point of view

An elastomer is an “elastic” polymer: it supports very great deformations (>> 100%) (almost) completely reversible S. On the contrary, a rigid polymer which would be deformed of 100% will keep in a permanent way an important deformation: it will be described as “plastic”.

This distinction between elastomers and other polymers corresponds to the behavior which one observes with room temperature. Indeed, the polymer reaction of depends on the temperature and the speed of request.

the elastomers are incompressible (or far from compressible) what is equivalent to a Poisson's ratio of 0,5.

Example of application: seals.

From their great deformability, the elastomers induce a progressive deceleration.

Example of application: damping of the shocks on the level of the heels in the shoes of jogging.

the great deformations of elastomers are reversible: important rebound.

Example: balls of Basque ball

Microstructural point of view

An elastomer is made up long molecular chains gathered, at rest, in “balls”. These chains are connected between them by points of reticulation, tangles or of the polar connections with mineral loads. They form a network.

The mechanical properties of elastomers depend initially on the length of the chains between the nodes of the network. More this length is the weak (dense network) more elastomer is stiff.

Current elastomers

The Fluoroelastomers (Viton, Kalrez,…)

The Latex

See also: Contenu=voir the article on [[latex]] the

The Neoprene

See also: Contenu=voir the article on [[neoprene]] the

Polyacrylic

See also: Contenu=voir the article on [[polyacrylic]] the

Polybutadiene

The polyethers block amides

See also: Contenu=voir the article on [[Polyether Block Amide]], [[polyethers block amides]]

The Polyisobutylene

Polyisoprene

The Polyurethane

See also: Contenu=voir the article on [[polyurethane]] the

The Santoprène

The Silicone S

See also: Contenu=voir the article on [[silicone]] the S

The Styrene Rubber Butadiene

See also: Contenu=voir the article on [[Styrene Rubber Butadiene]] the

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