A comparison: TPE vs TPR material
What’s TPE material? What is TPR? You’re not alone if you’re unsure of the differences between TPE and TPR. In this guide, we’ll look at how they compare, how they’re used and the advantages and disadvantages of each. We’ll cover:
TPE vs TPR
What's the difference between TPE and TPR?
What are SEBS and SBS?
What are your TPE choices?
The Shore durometer scale
What is TPE material?
Applications of TPE
What is TPR material?
Applications of TPR
Advantages of TPE
Disadvantages of TPE
Advantages of TPR
Disadvantages of TPR
TPE vs TPR
Both TPE material and TPR belong to the same family of thermoplastics. The TPE material meaning is thermoplastic elastomer. The TPR material meaning is thermoplastic rubber.
On the surface, their characteristics appear to be the same, from impact strength to good temperature resistance:
|
TPE |
TPR |
|
High-flexural fatigue resistance |
High-flexural fatigue resistance |
|
Resistant to tears and abrasions |
Resistant to tears and abrasions |
|
High-impact strength |
High-impact strength |
|
Good dielectric properties |
Good dielectric properties |
|
Excellent weather and chemical resistance |
Excellent weather and chemical resistance |
|
Recyclable |
Recyclable |
|
Modified from SEBS base material |
Often modified from SBS |
|
Temperature range: |
Temperature range: |
What’s the difference between TPE and TPR?
TPE and TPR definitely offer some differences, which really comes down to their base materials. TPE is modified from SEBS base material and TPR is often modified from SBS.
To better understand the difference in the manufacturing processes behind TPE and TPR, we must first break down the meaning of SEBS base material and SBS.
What are SEBS AND SBS?
Styrene Ethylene Butylene Styrene Block Copolymer (SEBS) is the product of hydrogenated SBS. But what exactly is SBS? It’s styrene-butadiene-styrene block copolymer, which offers soft-touch characteristics utilised extensively by designers – especially in hand tools.
What does this mean in relation to SEBS? By introducing molecular hydrogen to unsaturated molecules in special reaction conditions, SEBS molecular structure becomes saturated. This is why TPE material properties offer better ageing resistance, as well as yellowing resistance. On top of this, an SEBS substrate also ensures higher heat and corrosion resistance than SBS, therefore resulting in a higher performance output of TPE over the material TPR.
What are your TPE choices?
The material TPE falls into different groups. These thermoplastic elastomer materials include:
● Polyolefin blends (TPE-O)
● Styrenic block copolymers (TPE-S)
● Elastomeric alloys
● Thermoplastic polyurethane (TPE-U)
● Thermoplastic polyamides (TPE-A)
● Thermoplastic co-polyesters (TPE-E)
The Shore durometer scale
TPEs are certainly thermoplastic elastomers, but they still offer similar elasticity to their cross-linked rubber counterpart. This is determined by its softness or hardness, which is monitored on a scale known as the Shore durometer.
Available as soft gel materials – from 20 Shore OO up to 90 Shore AA – TPEs possess similar qualities to crosslinked rubber. After reaching 90 Shore AA, they are introduced to the Shore D scale, which means they can be formulated to achieve a hardness of up to 85 Shore D.
TPRs are available in a wide range of durometers, from 20 Shore OO to 85 Shore D – again, this aligns with TPE.
You can learn more about Shore durometer in What’s Shore hardness and why should you care?
What is TPE material?
Made up of soft and hard domains, TPEs are multiphase materials in their solid state. Some engineers may wonder why they’re rubbery – but there’s a very good reason for this.
The temperature range and unique design of TPE is determined by its glass transition temperature during the rubbery phase, as well as the melt temperature or glass transition during the hard phase of its manufacture. During processing, TPE material shrinkage typically falls between 0.5% and 2.5%.
Applications of TPE
What material is TPE found in? Just some of the applications where you’ll find TPE include the following:
Industrial machinery
TPE’s pliability makes it ideal for overmoulding to make knobs more ergonomic. TPE knobs are common when repetitive use is needed to ensure comfort for the user. The lobed knob here is an excellent example of ergonomics at work, combining both material and shape for the user.
Electronic equipment
Freestanding electrical and electronic equipment often use TPE feet. TPE rubber material is excellent at damping vibration, making them ideal for equipment enclosures as well.
Non-toxic, TPE really shines in medical applications. TPE material safety is excellent, which is why the material is often used to make tubes. The rivet mount foot shown here is ideal for medical appliances. There is no question about how to clean TPE material. TPE can be sterilised using ethylene oxide, autoclaves or gamma irradiation.
Specialty vehicles
Specialty vehicles such as tractors need protection for hydraulic couplings from dirt, moisture and corrosion. This quick release dust cap is ideal for the job. Designed to remain attached to the hose and available in blue, green, yellow and red. Another advantage to TPE: This dust cap has an operating temperature range of -40ºC up to 135ºC.
Enclosures
Open-hole grommets convert sharp edged holes in panels and enclosures into smooth openings. TPE is both solid and soft enough to make it an excellent material for protecting cables and wires as they pass through. Weather resistance makes it ideal for outdoor use in accordance with UL 746C.
What is TPR material?
TPR has qualities that combine the properties of rubber with the moulding capabilities of thermoplastics. The unsaturated molecular structure of TPR material is similar to that of rubber, which gives it its elastic feel.
The physical properties of TPR include these characteristics:
- Holds its shape
- Comes in varying levels of flexibility
- Flexibility can be increased by adding more rubber to the chemical makeup
- Can be formulated so the rubber smell is not noticeable
- Lightweight
- Can be coloured to your requirements
Applications of TPR
TPR is often used in applications that require glueing, such as footwear and toys, while TPE doesn’t react well to adhesives. TPR is also used in these applications:
Electronic equipment
Screw-on feet made of TPR are excellent at preventing slippage. Like TPE, TPR is good for damping vibration, which makes both an ideal material for feet. Because of it damps vibration so well, it’s also a common material used on workers’ gloves.
Sheet metal fabrication
Blanking plugs provide protection against sharp edges, and are ideal for closing panel cavities. Also called hole plugs, they protect against dust and moisture during the cleaning and manufacturing process.
Cabinets
Ideal castors for heavy-duty applications such as cabinets, trolleys, waste equipment and workstations. TPR wheels provide shock-absorption and protect floors with quiet rolling operation. It also resists cleaning chemicals.
Manufacturing
TPR side pull plugs are used to protect threaded or plain components from contamination and damage during shipment. Automotive parts are an example. The plugs feature a side pull tab for quick removal. The tapered design allows each size to fit multiple inner diameters while resisting chemicals and contaminants. Ideal for use in hard-to-reach positions.
Advantages of TPE
TPE has very good electrical insulation properties and resists heat and oils. It also offers low permeability and can be produced in different hardness grades. It gives you a soft touch, weather resistance, fatigue resistance and temperature resistance. Is TPE material safe? Yes – very much so – as already noted.
Another advantage of TPEs is the significant cost savings to manufacturers. They can be processed on plastics machinery, therefore reducing the overall price per project.
Environmentally friendly, TPE, like TPR, is 100% recyclable. Energy saving and requiring less man power overall, TPE materials are lightweight and suitable for high-volume injection moulding and blow moulding – it can also be used for secondary injection moulding.
You might find it helpful to read What is plastic injection moulding and how does it work?
Disadvantages of TPE
TPE’s heat resistance is not as good as that of rubber materials. Generally, the physical properties decrease as the temperature increases, so make sure you check the operating temperature range of the TPE materials you’re considering. Also be aware that the compression deformation, resilience and durability lag behind rubber.
Advantages of TPR
TPR combines the look, feel, and elasticity of thermoset rubber with the processability of plastic. Which brings us right back to where we started – the qualities TPR and TPE have in common. Like TPE, TPR offers good electrical insulation. It can also be used in injection moulding and blow moulding. And like TPE, it can be thermoformed.
TPR costs less than TPE and offers strong chemical and weather resistance, while standing up to a wide range of temperatures and durometers. It also shares TPE’s ability to be recycled and reused. Finally, is TPR material toxic? No. It’s safe to use for any application.
Disadvantages of TPR
Compared to vulcanised rubber, TPR is inferior when it comes to tensile strength, ageing resistance and mechanical properties.
Rubber materials are generally thought to offer improved tensile strength and that TPE materials are still deemed inferior in terms of their properties. You should judge the project and its components on their merits, using the right tools and kit for the job and ensuring plenty of forward-planning is in place.
TPE vs TPR material: Which is right for you?
You’ve been given the long version. If you’re still confused, then think of it this way: TPE is essentially a softer version of TPR. TPE is used when a bit more flexibility and softness is what you’re after.
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