An Introduction to Elastomers: A Type of Flexible & Durable Materials
Author: John Schober, Market Development Lead
At Chromatic 3D Materials, people often ask us about the difference between flexible materials like elastomers and rubber. Shorthand for “elastic polymers,” elastomers are engineered materials comprised of long chainlike molecules, or polymers. They are capable of recovering their original shape after being stretched to great extents. In other words, elastomers are a category of polymers that have elastic properties. Although the term “elastomer” is often used interchangeably with the word “rubber," this can create confusion. Real rubber has different definitions.
What is rubber?
Colloquially, of course, rubber is used to describe anything that is designed to deform and return to its original shape, without reference to the specific engineered material used (think of a rubber band or a rubber ball).
Natural rubber is a specific type of elastomer that is made from latex, a milky substance extracted from the sap of a rubber tree or other plants.
In the materials world, the term rubber is also used to clarify the nature of a specific engineered material, such as silicone rubber (as opposed to silicone gel) or polyurethane rubber (as opposed to other forms of polyurethane).
It's important to make clear distinctions when discussing rubber. Therefore, at Chromatic, we tend to use the word “elastomer” to describe the broad field of polymers with elastic properties or to reinforce the nature of specific engineered material. In this and subsequent articles, we will follow this convention.
Why use elastomers?
Because of their ability to be deformed and return to their initial shape, elastomers are preferred over other engineered metals (such as plastics or metals) in many applications.
Most elastomers are thermosetting, meaning that they cannot be remelted. Compared to thermoplastic materials, thermosets have superior mechanical properties because they have a higher degree of crosslinking.
As elastomer properties can vary, it's important to consider the following factors when selecting a particular material for an application.
Mechanical properties: hardness, tensile strength, elongation at break and compression set to perform in the intended application
Chemical resistance: resistance to chemicals and fluids it will come in contact with during the application
Temperature resistance: ability to withstand the temperatures it will be exposed to during the application without losing its mechanical properties
Durability: ability to withstand wear and tear and maintain its properties over the intended service life
Common elastomers
The following are some of the most commonly used elastomers.
Natural Rubber: a polymer made from the latex of rubber trees that contains repeating units of isoprene
Polyisoprene: a synthetic elastomer that is chemically similar to natural rubber
Butyl Rubber (IIR, Isobutene-isoprene): a synthetic elastomer with high resistance to gas and moisture permeation
Urethane (PU, Polyurethane): a synthetic elastomer that has high resistance to abrasion and impact, often used in the production of seals, gaskets and wheels
Chloroprene (CR, Neoprene®): a synthetic elastomer that has high resistance to oil, chemicals and heat
Ethylene Propylene Diene (EPDM): a synthetic elastomer that has high resistance to weathering, ozone and UV radiation
Fluorocarbon (FMK, Viton®): a synthetic elastomer that has high resistance to chemicals, heat and fuel
Fluorosilicone (FSI): a synthetic elastomer that combines the chemical resistance of fluorocarbon with the flexibility of silicone
Nitrile Butadiene (NBR): a synthetic elastomer that has high resistance to oil and fuel
Saturated Nitrile (HNBR): a synthetic elastomer that has a higher resistance to heat and chemicals than NBR
Silicone Rubber (SI, Gum and Liquid): a synthetic elastomer that has high resistance to heat and cold, often used in medical and food-grade applications
Styrene Butadiene (SBR): a synthetic elastomer commonly used in the production of tires and other automotive components
Common elastomer applications
Elastomers are used in a variety of consumer and industrial applications, including the following.
Consumer
Consumer electronics: phone cases, watch straps and other electronic accessories due to durability, flexibility and soft-touch feel
Sports and fitness: sports equipment such as running shoes, wristbands and fitness mats due to shock absorption, flexibility and slip-resistant properties
Toys and games: toys and games such as balls, action figures and game controllers due to durability, flexibility and soft-touch feel
Household appliances: blender seals, door gaskets and refrigerator liners due to resistance to chemicals, temperature and wear
Personal care products: toothbrushes, cosmetic applicators and hairbrushes due to flexibility and soft-touch feel
Automotive: seals, gaskets and suspension components due to resistance to chemicals, temperature and vibration
Industrial
Aerospace and defense: seals, gaskets and vibration dampeners due to resistance to temperature extremes, chemicals and shock absorption
Automotive: engine mounts, seals and gaskets due to resistance to chemicals, temperature, and vibration
Medical: catheters, implants and seals due to biocompatibility, flexibility and resistance to chemicals and fluids
Industrial machinery: seals, gaskets and vibration dampeners due to resistance to chemicals, temperature and vibration
Construction: seals, gaskets and waterproofing due to resistance to weathering, UV radiation and chemicals
Oil and gas: seals and gaskets due to resistance to chemicals, high pressure and temperature extremes
Further reading
This article is the first in a series about elastomers and additive manufacturing. If you want to learn more about 3D printing with elastomers, read the next article, “Elastomer Additive Manufacturing: Processes & Materials.”