Material selection is a key consideration when designing a new part or upgrading an existing design. Selecting the right material for a given application is crucial to a successful part design and performance in the field. A poor material selection can result in reliability or longevity issues or even have safety implications. For these reasons, it is imperative that OEMs get the material right the first time.
When it comes to elastomers, there is no shortage of options to choose from. Many industries prefer polyurethane as it offers many advantages over other elastomers. Before comparing the various elastomers, let’s first better understand elastomers.
What is an Elastomer?
An elastomer is an elastic material that can be stretched and when released, it will rebound to its original dimension and shape. An elastomer has both viscosity (resiliency) and elasticity.
In terms of chemistry, elastomers are loosely cross-linked polymers. This is an important characteristic as more cross-links in the polymer chain would result in more rigidity. These long and randomly coiled materials can easily be stretched but return to their original shape when the force is removed.
Urethane is just one base polymer that can be used to manufacture elastomeric products. In fact, there are many examples of elastomers on the market such as natural rubber, silicone, nylon, butyl, nitrile, and urethane. These materials are found in a myriad of applications across a range of industries including automotive, marine, food processing, and military.
What Are Thermosets?
Depending on the distribution and degree of the chemical bonds of the polymer, an elastomer can have properties or characteristics similar to thermosets or thermoplastics. Most elastomers fall into the thermoset category, but PSI custom urethane can be formulated to be thermosets or thermoplastics.
Thermoset elastomers are polymers that cannot be melted and reformed and are generally more durable than thermoplastics. For example, thermoset polyurethane is a versatile material that, depending on how it is formulated, can range in physical properties from soft and malleable to tough and hard.
Chemically, thermoset elastomers, like thermoset polyurethane, are formed from a variety of prepolymers, curatives, and additives. By varying the nature of these components, the team at PSI Urethanes can create numerous formulas and combinations of properties. Because of this versatility, polyurethanes can be custom tailored to suit a wide variety of applications.
Would your project benefit from the longevity and durability of a custom urethane product?
Contact the experts at PSI to learn more about our custom urethane solutions including thermoset polyurethane.
Comparison of Thermoset Polyurethane and Other Elastomers
When selecting a material for your part, it is important to clearly understand the pros and cons of each material being evaluated. The following provides the advantages and disadvantages of several elastomers including PSI’s thermoset polyurethane.
- Graded as Excellent for abrasion resistance, tensile strength, ozone, UV resistant
- Durometer range from “OO” to “D” scale Esters have excellent tear strength and ethers have excellent rebound resilience
- Excellent gas impermeability, oil and absorbs trace amounts of water
- Comes in FDA compliant and static dissipative formulas
- Outlasts rubber products by a minimum of 5 times longer
- Rated Poor for some acids and solvents
- Does not do well in steam
- Not all formulations have good tear strength
- Can cost more upfront than plastics or rubbers
- Not good with high heat consistently over 180°
Wheels, seals, rollers, gaskets, bumpers, capper rings for the bottling industry, wear pads for the hydraulic press industry, custom parts for assembly lines and process automation
- Graded as Good on tensile strength, elongation at break and tear strength, gas permeability, water, oil, alcohol
- Graded as Poor for rebound resilience and Ozone and UV
- Due to abrasion resistance ratings this material is not good for all applications involving degreaser solvents
Gloves, fuel hoses, gaskets, rollers, molded and extruded products
- Graded as Good on tensile strength, elongation at break and tear strength, rebound resilience, ethanol and water
- Graded as Poor for gas impermeability, ozone and UV
- Poor resistance to petroleum-based fluids
Hoses, gaskets, seals, coated fabrics, belting, roll coverings
- Graded Excellent for compression set from 20°C to 150°C
- Steam and Heat resistant from 581° F to -212° F
- Hygienic – non-toxic and water repellent
- Graded as Poor for tensile strength, elongation at break, tear strength, abrasion resistance, and rebound resilience
- Ranges from Poor to Unsuitable for several contaminants
Automotive, electrical insulation applications, moldings, membranes, gaskets, extruded sleeves, cooking & baking applications
- Resistant to gasoline, oils and elevated temperatures. Good weathering resistance Flame retarding Moderate resistance to petroleum basked fluids Good physical properties
- Affected by aromatic hydrocarbons, phosphate and hydraulic fluids
- Absorbs water over time
Industrial applications, electronics, safety equipment and construction, medical applications, marine, automotive
- Graded as Good for tensile strength, elongation at break and tear strength, and ozone and UV resistance
- Excellent dielectric properties
- Water, ethanol, and gas impermeability rating
- Rated Poor for abrasion resistance, rebound resilience, and mineral oil and petrol resistance.
Manufacturing automotive vibration control, hoses and gaskets, medical applications; used to improve formulations for conveyor belts, tank linings and condenser packaging.
- High strength wear
- Waterproof and solvent resistant
- Easy to wash and produce
- Low cost
- Lightweight, fire retardant, and can be made in FDA & USDA approved formulations
- Very little give to the material and can be dented upon impact
- Attacked by acids, ozone and oxidizing agents
- Very small hardness range of 60D to 80D
- Max operating temperature is 180°F and min operating temp is -30°F, melts at 255°F
Electronic test equipment, machine guards, seals, rotor slot wedges, wheels, wear pads, medical implants
- Rated Good for abrasion, tensile strength, elongation at break, tear strength, rebound resistance, gas impermeability, ethanol and low temperature resistance.
- Rated Poor for petroleum-based fluids, with animal fats and greases
- Sensitive to temperature changes.
- Attacked by sunlight, ozone, heat, weather and absorbs moisture.
Anti-vibration mounts, drive couplings, springs, rubber bands, bearings, wheels, tires, seals and gaskets
- Ozone and UV resistant, Steam resistant and can take heat up to 392°,
- Tensile range of 500-2500 psi and 600% elongation
- Excellent rating with water, ozone & UV
- Not recommended for food use
- Only fair for tear strength, abrasion and rebound resistance
- Vulnerability to solvents, hydrocarbon oils, and some lubricants
Seals and o-rings, tubing, washers, electrical cable-jointing
- Very good chemical resistant properties and corrosion resistant
- Extremely low water absorption
- Non-sticking, self-lubricating, and non-toxic
- FDA & USDA approved
- Very little give and can be dented upon impact
- Attacked by oxidizing agents
- Does not bond well to other materials
- Very small hardness range 62D to 66D Will deform under constant load (known as “creep”)
- Maximum operating temperature 180°F
Hoppers, food service cabinetry, docks & doc fenders, conveyor system parts such as bottle protector guides, star wheels and wear strips, outrigger pads
So Which Elastomer is Best for My Project?
After reviewing the table above, you may be asking – which elastomer is best for my project? The answer is that it depends. Each part and application are unique so the right material for your part depends on your specific situation.
When creating a design for a new or existing product, it is paramount to thoroughly understand the application and expected operating conditions. At PSI, we know that environmental elements such as heat, humidity, ozone, acids, chemicals, UV light, and water can have a detrimental effect on the function of the part; thus, our team must account for these conditions when developing a custom urethane formulation in order to minimize the impact of these environments. Our customers also provide details about the desired functionality of the part such as hours of run time per day, speed, load, and if the cycles are continuous or intermittent. Clearly communicating information about the operating environment gives your custom urethane supplier a good understanding of how to achieve a formulation that provides maximum results.
About PSI Urethanes
Since 1966, through our own independent research and activity in the Polyurethane Manufacturers Association, PSI Urethanes has stayed on the leading edge of urethane technology – including developing advances in new materials, comprehensive designs, and processing technologies. Today we are among the most respected and trusted suppliers of custom urethane products.
We operate from our 45,000-square-foot manufacturing facility in Austin, Texas, which houses an extensive stock of polyurethane products. Our fully equipped manufacturing facility includes a versatile range of processing machinery, which allows us to work on unique, one-of-a-kind projects, as well as high volume components. Our in-house engineering, tooling, and custom mold shop, produces custom and stock production orders with exceptionally fast turn-around times. From conception to prototyping, to final production runs, our technical representatives and design engineers will work closely with your staff to meet your critical tolerances and specifications. You are guaranteed to receive experienced, professional, and personalized service from the first contact through your on-time delivery, with complete confidentiality and dedication to protecting your good name.
PSI Urethanes specializes in custom urethane products. Contact us today to see how we can help with your next project, or give us a call at 1-800-888-5156.