Elastomer 101: The Basics of Rubber

The demand for industrial rubber products touches near every industrial sector. Rubber’s unique properties supply many performance-demanding applications, and it’s no wonder that the current market value of $106 billion in 2018, and an expected growth rate of 6% through 2027. It is widely used in the construction and infrastructure projects, and in terms of volume, the automotive industry is rubber’s largest consumer.

Rubber has excellent mechanical and physical properties — dimensional stability, strength, and resilience; a low modulus of elasticity means it is capable of sustaining deformation up to 1000 percent and then just as quickly retract to its original dimensions. Along with its dampening properties and electrical insulation, impact, and abrasion resistance, it also functions in a wide range of temperatures. It is permeable, resisting the passage of air, gasses, steam, chemicals, water, and other fluids. It’s environment-friendly, too, used in recycled rubber playground surfaces, flooring products, shoes, tires, mulch, matting, water bottles, and much more.

What Is Rubber and How Is It Made?

Defining what rubber still remains a source of confusion, due in large part to it being both a natural and synthetic material. Whether natural or synthetic, each is an elastomer, a word that commonly refers to as any material with rubber-like properties. Elastomer is short for elastic-polymer, which only adds to the confusion because polymers are generally viewed as another word for plastics—the synthetic elastomer derived from petroleum. Natural rubber is an elastomer which is made from a type of latex extracted from the bark of the rubber tree, the hevea brasiliensis.

To clear up the confusion, think of natural rubber as the prototype of all elastomers, and elastomers as a subset of polymers. When you see or hear the word ‘elastomer,’ think ‘elastic,’ because the elasticity of elastomers is the main reason why elastomeric polymers are often used interchangeably with the word, ‘rubber.’ Nevertheless, in industrial rubber products, an elastomer is a synthetic polymer with viscoelasticity, meaning its properties have both viscosity and elasticity.

Elastomer materials are made from polymers joined by chemical bonds with a slightly cross-linked structure. Without the cross-linkages, the applied stress would result in permanent deformation. Because of it, the material is characterized by high elongation, flexibility and, as mentioned, elasticity. This helps prevent the material from cracking, snapping, or breaking when deformed.

As a polymer, elastomers are considered a pliable polymer, or plastic, material that includes synthetic and natural rubber. Elastomers are used in countless applications for vibration dampening and insulation — molding, gaskets, seals, shock absorbers, tires, skateboard wheels, soles of sneakers, and electronic cabling and wire insulation, and so on.

What Is Vulcanization?

Rubber’s effectiveness is a result of vulcanization, a chemical process in rubber production where it is heated with sulfur and other chemicals to 280-350 degrees Fahrenheit. Vulcanizing cross-links rubber molecules to enhance and improve its physical and mechanical properties. The process not only allows the rubber to perform and function in wide temperature ranges, but improves its elasticity, hardness, increases its tensile strength, weather resistance, and viscosity. Without vulcanization, the mechanical properties of rubber are relatively unstable. For example, it becomes sticky in hot weather and brittle in cold.

What Is Compression Set?

In some ways, compression set can be viewed as rubber’s kryptonite. It is a permanent deformation of a material after compressive forces have been applied to it over a prolonged period of time. In elastomeric materials, prolonged compression causes the material to lose its resiliency and deflection, i.e., the capacity to return to its original form. For example, in gaskets and shock absorbers, the inability of rubber to return to its original thickness or shape results in a permanent set of the material, a deformation that causes the component to fail—cracking, leaks or loss of shock resistance. Compression set resistance is an important mechanical property of elastomeric material. It is expressed as a percentage. The lower the percentage of the elastomeric component the better compression set resistance it offers.

What Is the Difference Between a Thermoset and Thermoplastic?

Elastomers can hold both thermoset and thermoplastics properties. Thermoset and thermoplastic are two separate types of polymers or plastics used in the production of parts, components, and products. The primary difference between the two is in the application of heat and how the physical and chemical properties react to it. With the application of heat, the structural integrity of one is permanent and the other is not.

Thermoset polymers can resist high heat without losing their physical properties, whereas thermoplastic polymers cannot. Thermosets strengthen when heated. In fact, they are produced from a liquid state at room temperature and then injected into an extremely hot mold to create the part. Once set, the part can never be remolded. On the other hand, thermoplastics have a low melting point. The polymers can be remolded time and again without causing any chemical changes to their properties.

Contact the Experts at Manufacturer’s Rubber

If you are in the market for or have questions about industrial rubber products, contact us at Manufacturer’s Rubber & Supply today. We are your trusted source for any and all rubber product needs!

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