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Common Elastomer Properties

What Are Elastomers?

Elastomers are synthetic or natural materials capable of repeated stretching without losing their original shape. Natural rubber is one of the most widely known elastomers. Choosing the best elastomeric material for your industrial needs requires understanding the different types of elastomers on the market. Below are common elastomers and how they fall into various categories, with some overlap based on their appropriate applications.

These general-purpose elastomers are some of the most common in use today:

  • Neoprene
  • Natural Rubber
  • SBR
  • Silicone Rubber

Examples of high-temperature elastomers include:

  • Neoprene
  • Viton®
  • Silicone Rubber
  • EPDM

Low-temperature elastomers include:

  • Silicone Rubber
  • Butadiene
  • Butyl
  • Natural Rubber

High-performance engineered elastomers, such as neoprene and butadiene, have a higher price point and offer greater durability in harsh operating environments. These oil- and hydrocarbon-resistant elastomers are also essential, such as for pressurized seals in chemical manufacturing.

Because the properties of many elastomeric materials have significant overlap, choosing exactly the right elastomer for your application requires working with a specialist in elastomer applications.

Common Elastomer Properties

An elastomer’s properties are the combined result of several performance factors.

Specific Gravity

Specific gravity refers to the elastomer’s density compared to water. This property provides several indications of the elastomer’s strength, weight, and the media it can contain. Knowing the material’s specific gravity helps manufacturers evaluate the product’s ability to withstand heavier loads without becoming brittle, its wear resistance over time, and the rate at which it absorbs solvents and oils.

Most elastomers have a specific gravity between 0.9 and 2.0. Viton®, urethane, and neoprene have the highest specific gravity out of all rubber materials at 1.86, 1.25, and 1.25.

Durometer Range

The durometer rating provides a relative comparison of hardness for materials. For example, most rubber materials are measured by either the Shore A or Shore D durometer scales. Shore A durometer ratings cover soft materials to certain semi-rigid and inflexible plastics. Shore durometers measure harder materials, including semi-rigid plastics and hard rubbers and plastics.

Silicone rubber has one of the lowest durometer ratings (Shore A 20-30) of any elastomer, making it suitable for cushioning or molds. Nitrile has a higher durometer rating (Shore A 60-70), which makes it effective for high-pressure seals and gaskets.

Strength

There are several measures of elastomeric strength. It’s important to know what type of strength your elastomer application requires.

  • Tensile Strength measures the elastomer’s breaking point.
  • Elongation at Break indicates how much the elastomer will deform before it reaches the breaking point. A higher elongation at break value normally comes at the expense of lower tensile strength.
  • Tear Resistance denotes the level of force required to tear the material.
  • Impact Strength measures how well an elastomer resists sudden impacts and shock loads. Other variables, like the elastomer’s temperature and thickness, can affect its impact strength. Elastomers with the highest impact strength include natural rubber, SBR, and urethanes.
  • Abrasion Resistance shows how well the elastomer resists scraping, rubbing, erosion, and other mechanical forces. Examples of elastomers with exceptional abrasion resistance include polyurethane, nitrile, and SBR.
  • Compression Set Resilience is a measure of an elastomer’s height loss or deformation after withstanding a compressive force for some time. It also relates to how well the elastomer returns to its original shape. Seals, gaskets, and O-rings face continual compression, so they require elastomers with the best compression set resilience. Natural rubber generally has a very high compression set resilience, although this depends on the formulation.

Temperature Resistance

Elastomers also deteriorate under excessive heat. Heat aging and other temperature resistance tests can simulate the elastomer’s behavior under extreme temperatures and help establish its expected service life under particular conditions. Viton® and silicone rubber have the best flame resistance and highest operating temperatures, up to 400-485 °F.

Low temperatures render elastomers brittle and stiff, and rubber crystallization is a risk mostly for non-vulcanized rubber. Silicone rubber has the best low-temperature resistance, as low as -180 °F.

Elemental Resistance

This property refers to an elastomer’s resistance to outdoor elements. These tests (and associated standards) help determine the material’s elemental resistance:

  • Dielectric Strength – ASTM (D-149)
  • Heat Aging – ASTM (D-573)
  • Ozone – ASTM (D-395)
  • Water – ASTM (D-1149, D-1171)

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Properties of Elastomers

Premium Elastomers From RubberMill

With more than 30 years of experience in the industry, RubberMill provides OEMs across diverse industries with the high-quality nonmetallic parts they need. Our technical, engineering, and sales teams work together to help customers determine which elastomers will best meet their goals. We consider every design factor, delivering reliable custom gaskets, insulation, and acoustic and vibration control solutions.

To learn more about which types of elastomers are most suitable for your specific product or application, contact us or request a quote today.

ASTM Testing Methods for Elastomers

American Society for Testing and Materials (ASTM) is a global organization with thousands of members who are technical experts in different fields. They work to develop and publish comprehensive standards, consisting of test methods, specifications, classifications, guides, and best practices for different materials, products, and systems used in many industries.

Ensuring the elastomers used in your products meet ASTM standards is a major step toward meeting product performance and safety requirements, quality expectations, and longevity.

To aid in the classification of materials and products, all ASTM documentation uses a system of letters. The letters A through G designate broad material categories. Most elastomers are grouped under ASTM D, “miscellaneous materials and products.”

In this article, we’ll focus on some of the many common ASTM testing standards for elastomer materials.

Common Elastomer ASTM Test Methods

ASTM test standards describe why and how to conduct specific tests on materials or processes. The standards explain the scope of the test, what it measures or observes, specifications for equipment used in testing, specimen requirements, and procedures for the test.

Generally, the tests listed below allow manufacturers to measure and observe the properties, behaviors, changes, and limitations of different types of vulcanized thermoset rubbers and thermoplastic elastomers. To obtain accurate results, all tests must be performed under controlled conditions with specialized and properly calibrated machinery.

Some of the most common tests for elastomers include, but are not limited to:

  • ASTM D412 (Tensile/Elongation). This is a test of the material’s ability to withstand tensile forces. Tensile properties including tensile strength, tensile stress at a given elongation, ultimate elongation (the point of rupture), and tensile set or residual deformation are measured before and after applying force. This test is conducted using a universal testing machine, also referred to as a tensile testing machine or pull tester.
  • ASTM D624 (Tear Resistance). This test measures resistance to tears by finding the force per unit thickness required for the specimen to rupture or tear. Typically, any materials that are tested to D624 also undergo ASTM D412 testing to measure tensile strength and elongation.
  • ASTM D395 (Compression Set). This test observes the material’s compression set, or its ability to retain elasticity after prolonged exposure to compressive stress. The test can be performed with a static force applied to the material or a rapid repeated deformation and recovery. This test is particularly applicable to elastomers used in seals, vibration dampers, and machinery mountings.
  • ASTM D2240 (Durometer). This is a method for measuring the durometer hardness of rubber materials. The material is compared to 12 established, universal reference scales called shore hardness scales (Types A, B, C, D, DO, E, M, O, OO, OOO, OOO-S, and R). The test is performed by measuring the depth of an indentation made in the specimen under controlled conditions.
  • ASTM D573 (Heat Resistance). This test assesses physical and chemical changes to the material when exposed to heat. Elastomers must be able to resist deterioration of physical properties caused by thermal and oxidative aging. This testing procedure offers a way to assess certain performance characteristics of rubber under the specified accelerated conditions. Properties are measured before and after exposure.
  • ASTM D1171 (Ozone Resistance). This is a test to determine molded or extruded rubber products’ resistance to ozone cracking and outdoor weathering. The test does not apply to hard rubber materials but can be adapted to extruded or molded soft rubber materials, as well as sponge rubber used for automotive applications (i.e. window weatherstripping).
  • ASTM D471 (Fluid Resistance). Elastomers used for gaskets, seals, diaphragms, sleeves, and hoses are often exposed to fuels, greases, oils, and other fluids during operation. This test assesses a material’s ability to withstand the effects of these liquids by simulating operating conditions via controlled accelerated testing.
  • ASTM D297 (Chemical Analysis of Rubber). This is a group of quantitative and qualitative tests used to analyze the composition of natural and synthetic crude rubbers. The methods are divided into general and specific testing categories. Part A tests look at the type and amount of major constituent compounds, while part B tests determine the specific polymers present.

Related Resources

At RubberMill, we provide testing services for several of the ASTM tests commonly required for new product development.

View our elastomer physical and analytical testing chart here.

A chart of chemical resistance information for nine common elastomers is available here.

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Elastomer Testing Services

Elastomer Products by RubberMill

RubberMill is an ISO 9001:2015 certified non-metallic component manufacturer with over 30 years of experience. We are a trusted resource for ASTM testing as well as materials for custom die cutting, lamination, and more. A variety of die cut and molded parts are also available in stock.

Please contact us or request a quote to learn more about our capabilities or to talk with an expert about your next project.

The Industrial Flatbed Lamination Process

Flatbed lamination is a process that involves using pressure and heat to join multiple materials, producing a multi-layered composite with improved properties. Compared to PSA lamination, which involves creating a sticky, adhesive surface to bond materials with, industrial flatbed lamination can create specialized laminates such as multi-layered sheets or rolls.

Industrial flatbed lamination is used across diverse industries for applications such as automotive components, packaging, insulating panels, and molding precursors. This process not only produces a high-quality finish but also can improve the appearance of products, add a protective barrier, and to reduce material thickness when desired.

The Basics of Industrial Flatbed Lamination

Flatbed lamination is used to combine different materials such as foam, film, fabric, and nonwoven materials to produce a composite material with improved characteristics. The main goal of industrial flatbed lamination is to create materials with highly specialized properties, such as enhanced structural integrity or insulation.

This process is especially beneficial for creating products with a smooth, level surface from raw, uneven substrates. As such, it allows for the use of more economical materials compared to other lamination processes. Flatbed laminators also facilitate precise thickness reduction and material densification of certain foams, nonwovens, and other substrates.

Depending on your particular needs, the adhesion between the materials being laminated can be achieved using thermoplastic adhesives in the form of webs, powders, and films. Some materials can even be laminated without the need for additional adhesives due to their inherent thermoplastic characteristics.

Types of Industrial Lamination at RubberMill

At RubberMill, we utilize highly advanced Pressurized Flatbed Laminating technology that employs zoned heating, cooling, and pressure to produce unique material composites. Using a range of material combinations as well as adhesive films and webs, we can create the desired end product. For example, we can combine nonwoven materials with films or fabric with foam.

If the main goal is the application of pressure sensitive adhesives, RubberMill also offers PSA lamination services using dedicated equipment. The finished PSA laminated product can be converted into continuous rolls of stripping or cut into separate parts.

With over three decades of industrial lamination expertise, RubberMill can deliver innovative solutions to meet the needs of various industries and applications. This level of experience allows us to provide finished laminated products that adhere to specific OEM requirements.

The Technology Behind RubberMill’s Lamination Process

Our advanced belt press lamination machine uses a horizontal flat conveyor run, allowing it to accommodate materials of various thicknesses and widths. By applying customized amounts of pressure, heating, and cooling, our machine enables precise control over the properties of the end product.

To meet the needs of sensitive applications, RubberMill’s lamination process includes continuous full-width thickness monitoring, including product-specific settings that can be stored electronically for the duration of the laminating process. Our machinery is also capable of creating sheets with specific dimensions and can automatically trim the edges to ensure uniform roll width.

Our lamination technology is highly cost-effective due to its high speed and minimal energy and adhesive consumption. This makes it a sustainable option for all of your industrial lamination needs.

Benefits of Contract Lamination with RubberMill

By outsourcing your industrial lamination needs to RubberMill, you gain access to the following benefits:

  • Cost savings.Outsourcing your lamination process reduces costs associated with investing in additional machinery and manpower.
  • Speed. Our level of expertise ensures a fast and efficient manufacturing process. This results in a quicker time-to-market for your laminated products.
  • Turn-key. Our in-house die-cutting capabilities allow RubberMill to provide a turn-key lamination solution. This eliminates the need for you to transport your laminated materials for further converting.
  • Eco-friendly. Industrial lamination is a more environmentally friendly alternative to flame bonding and other lamination processes that emit toxic fumes.

Take Your Industrial Lamination to the Next Level: Contact RubberMill Today

Contract laminating helps companies save significant amounts of time and money on specialized material finishing processes they’re likely unequipped for. At RubberMill, we offer contract flatbed lamination and well as other lamination services to deliver the unique composites you need. For more information about our industrial lamination capabilities, or to get started on your contract laminating solution, request a quote from us today.

Thermal vs. Acoustic Insulation

Many types of heavy machinery, appliances, and other equipment require thermal and acoustic insulation to prevent excessive heat and noise. These products protect operators and keep machinery working reliably. As a leading provider of quality thermal and acoustic insulation products, RubberMill can help you better understand how these products work and the different types available.

Thermal vs. Acoustic Insulation

Thermal and acoustic insulation serve different functions but are used throughout many similar applications. Let’s explore what exactly these products are, their benefits, and the materials options available.

What is Thermal Insulation?

Thermal insulation is a product used to reduce heat transfer between solid objects, fluids, or gasses. It works by forming a lower temperature barrier between heat-producing components that prevents heat transfer. Thermal insulation is used throughout many industries, including medical, energy, industrial, and more. These applications all involve machinery that requires an optimal thermal environment for efficient performance.

Benefits of Thermal Insulation

Thermal insulation products provide a number of advantages:

  • Energy conservation
  • Hotspot prevention
  • Surface temperature reduction
  • Operator protection and comfort
  • Electronic component protection

Common Types of Thermal Insulation

There are two primary types of heat-resistant materials: heat reflection and insulation. Insulation keeps heat confined within a space, minimizing convective and conductive heat flow. Radiant materials, on the other hand, reflect heat energy from traveling in a straight line, thereby reducing heat gain.

Thermal insulation products are made using many types of materials:

What is Acoustic Insulation?

Also known as sound insulation, acoustic insulation reduces the transfer of noise. Sound is made up of vibrations and acoustic insulation products reduce noise by either redirecting it, absorbing it, or transmitting it. These products can be designed to target specific noise frequencies.

Benefits of Acoustic Insulation

When acoustic insulation materials are used to line hard objects like engines or heavy machinery, the porous material prevents sound waves from reflecting back at workers and the nearby environment. These materials are utilized in automotive, HVAC, and appliance applications to provide quiet operation of the device.

Common Types of Acoustic Insulation

There are two main types of acoustic insulation: absorbers and barriers.

Absorbers

Absorbers take in and trap sound waves, reducing the amount of noise in an area and improving its acoustic conditions. Absorbers can be applied to walls, ceilings, floors, and even objects. They can be made from several materials:

  • Open-cell elastomeric foam
  • Melamine
  • Nonwoven fiber materials
  • Cellulosic fibers
  • Dimensional fabrics
  • Urethane
  • Glass fiber materials
Barriers

Acoustic barriers block noise from transmitting between locations. In this instance, sound is not absorbed by the material but bounced back to the original location. Common types of acoustic barriers include steel or concrete. While durable, these options can be expensive to manufacture and ship and are not very eco-friendly. This type of insulation is also limited in the sense that it is for larger projects such as construction walls, whereas foam absorbing materials can be used in tight-fitting appliances and automotive parts.

Thermal and Acoustic Insulation Products From RubberMill

Thermal and acoustic insulation products are used throughout numerous industries, including automotive, consumer appliances, heavy machinery, and more. Each of these applications requires reliable, high-quality products to ensure operator and equipment safety. RubberMill has over 30 years of experience meeting OEM needs for quality and precision insulation products. To learn more about our solutions, contact us or request a quote today.

Different Kinds of Rubber

When to Use Different Kinds of Rubber Materials

As a trusted supplier of non-metallic parts, RubberMill is knowledgeable in rubber types. The components we produce, such as gaskets and seals, insulation parts, and molded parts, can all be made from a variety of high-quality rubber materials. This blog post will explain the different types of rubber and when they should be used for various applications.

Properties of Rubber

Rubber comes in several variations, each with its own unique properties. However, each distinct rubber type also shares common characteristics, including: 

  • Elasticity: Rubber materials all feature a molecular structure that allows them to return to their original shape after being stretched or compressed. Since rubber molecules are all attached to one another, they return to their original position. 
  • Thermal contraction: Rubber contracts when heated and returns to its original state after the heat is removed. This is opposite to most other types of materials that expand when heated. 
  • Durability: Rubbers resist degradation and damage well and are highly durable in the face of tearing and abrasive forces, water, low temperatures, and impacts. 

 

What Are the Different Kinds of Rubber Materials and When Should You Use Them?

There are numerous types of rubber, each best suited for different applications:

  • Ethylene propylene (EPDM, EP, BA, DA): EPDM has quickly become a popular general-purpose elastomer. It is highly resistant to weathering, oxygen, steam, ozone, and diluted acids. EPDM is non-oil resistant and is widely used to produce everything from door and window seals to roofing materials, pipe gaskets, seals, rubber hoses, and much more. It has an estimated shelf life of 5-10 years. 
  • Natural rubber (NR, IR, AA): Also known as polyisoprene, natural rubber was the first commercially available rubber type. It is naturally produced from the Hevea Brasiliensis tree and is mainly harvested in Indonesia, China, India, and Thailand. Natural rubber is used to produce automobile tires, bumpers, vibration mounts, gaskets, and much more. It has an estimated shelf life of 3-5 years. 
  • Styrene butadiene rubber (SBR, BR, AA, BA): Initially developed during the 1930s, SBR was widely used during World War II and is currently produced more than any other type of synthetic rubber. It is used to make footwear, clothing, toys, tires, and more. It has a shelf life of 3-5 years. 
  • Butyl (IIR, AA, BA, CA): First commercialized in 1943, Butyl rubbers are highly impermeable to gases and air and also feature excellent ozone and oxidation resistance. Since they have high energy absorption properties, they are used to produce inner tubes, shock absorbers, and seals. Butyl has an estimated shelf life of 5-10 years. 
  • Nitrile (NBR, BF, BG, BK): Initially developed in Germany for gasoline and oil-related applications, Nitrile is a synthetic rubber with excellent resistance to aromatic hydrocarbons. It is used in oil and grease seals, washers, check valve balls, and numerous other applications. It has an estimated shelf life of 3-5 years. 
  • Neoprene/chloroprene (CR, BC, BE): First developed in 1932, Neoprene is a rubber-like material that is resistant to ozone, oil, and low temperatures. It is also self-extinguishing. Neoprene is used in the production of seals, o-rings, grommets, bushings, and other components. It has a shelf life of 5-10 years. 
  • Urethane (AU, EU, BG): Urethane elastomers are available as both solid millable gums and liquid castable materials. They are a combination of either polyethers or polyesters and diisocyanates. Urethanes feature excellent abrasion resistance, load-bearing capacity, and tensile strength. They are also highly resistant to oils and solvents. Urethane is used to produce solid tires, wheels, shock pads, valve balls, and other components. It has an estimated shelf life of 5-10 years. 
  • Silicone: Initially patented in 1944, silicone is easily extruded, calendared, molded, and cast into various shapes. It displays excellent thermal stability up to 500 °F and is also resistant to oxygen, sunlight, and ozone. Silicone offers good electrical insulation and features low toxicity as well as flexible and anti-stick properties. Its use is growing in the automotive, medical, and industrial industries, and it is currently used to produce tubing, spark plug caps, door seals, valve balls, bellows, and more. Its shelf life is up typically up to 20 years. 
  • Viton®/fluorinated hydrocarbon (FKM, HK): Viton is a very expensive, high-performance elastomer. It is used in applications that require extreme oil, heat, and solvent resistance. Viton is widely used to manufacture components for the aerospace, automotive, and chemical processing industries, such as o-rings, gaskets, and seals. It is a registered trademark of Dupont Performance Elastomers and features a shelf life of up to 20 years. 
  • Butadiene (BR, AA): The second most commonly used synthetic rubber after SBR, Butadiene is the most resilient of all elastomers and exhibits excellent flexibility in low temperatures. It is used with other types of rubber as a blend to manufacture tires and is also used to produce golf balls, vibration mounts, and other molded industrial products. It has a shelf life of 3-5 years. 

 

Diecut and Molded Rubber Parts From RubberMill Inc.

Rubber is used to produce components for nearly every industry. The numerous rubber types available feature unique characteristics that enhance their suitability for diverse applications. RubberMill Inc. has over 30 years of experience delivering high-quality rubber components, and we can help you identify the most suitable material for your application.

To get started on your non-metallic parts solution, contact us or request a quote today.