Elastomers are any rubbery materials that can recover their shape after being stretched. They are made of long chain-like molecules known as polymers. Their name comes from a combination of elastic and polymer.
Elastomers were originally created as an alternative to rubber. They have been adapted to include properties that are valuable to manufacturing, including resilience to aggressive chemicals, hot temperatures, strength and flexibility.
With force, the molecules stretch in the direction they are being pulled and when released they return to their natural shape.
The oldest elastomer is that derived from natural rubber which is taken from the latex of various trees but mostly the Hevea (rubber tree). This natural rubber is still used in many industrial applications but has been overtaken by more synthetic forms.
The synthetic forms have been adapted for performance including sealing, flexibility, durability and strength. They can replace metal in many industrial applications. They are commonly used in silicone hoses from companies like https://www.goodflexrubber.com/pages/silicone-hose-manufacture, as well as cables, clothing and adhesives.
How are they made?
Elastomers are compounds that are made of five to ten ingredients. The polymer determines the resistance to heat and chemicals. Carbon is then added to provide strength to the compound. A plasticiser is then added to increase efficacy at lower temperatures. On top of this, other additives are used to create a polymer for a specific application such as antioxidants, a flame retardant, an accelerator and curer for speeding up and determining curing. The compound is made by adding the ingredients together into a mould where it is cured.
The curing process is vital and is carried out at high temperatures which helps create the long chains. These chains are what gives the product its elasticity and recovery. The properties are vital for determining the applications for the elastomer.
The processing techniques help determine the outcome of the finished product. Injection moulding can be used where high pressure forces the compound through rubbers into a mould. Compression can also be used to process elastomer with high viscosity. The compression creates a form that can be placed into a mould and cured. Extrusion is used for hoses and tubes in a steam autoclave followed by a mandrel designed in the required shape for the tubing.