What are TPEs? 
Possibilities and limits of TPE classes

Thermoplastic elastomers (TPEs) are materials that combine the elasticity and softness of classic elastomers with the processability of thermoplastics. They are recyclable, versatile and can be processed efficiently by injection molding and extrusion. But how do the individual TPE classes differ from one another? 

TPU, TPV and TPS - a comparison of thermoplastic elastomers 

According to ISO 18064, TPEs are divided into various subgroups:  
 

• TPU - Thermoplastic polyurethanes

• TPV - Thermoplastic vulcanizates

• TPO - Thermoplastic olefin elastomers

• TPC - Thermoplastic copolyester elastomers

• TPA - Thermoplastic copolyamides

• TPS - Thermoplastic styrene block copolymers 

TPU - Thermoplastic polyurethanes

Thermoplastic polyurethanes, TPU for short, are generally polyadducts made from polyisocyanates and polyols. In most cases, specific material properties are already adjusted during polymerization by selecting and combining different raw materials.  

TPU is characterized by high mechanical strength. The hardness of thermoplastic polyurethanes is typically between 60 and 80 Shore D. TPU has good chemical resistance to non-polar media such as oils or fuels. However, the material tends to hydrolytically degrade on contact with water and aqueous solutions, especially at elevated temperatures, which can limit its application possibilities in humid environments. 

TPU is processed by injection molding and extrusion. Careful pre-drying is essential here, as moisture in the material can lead to processing problems and quality losses. The specific processing instructions of the respective manufacturers should also be strictly observed, as excessive temperature, shearing or long residence times can thermally damage TPU and lead to stickiness or degradation. Nevertheless, the excellent abrasion resistance of TPU is often convincing enough to deal with the potentially challenging processing.

Typical applications for TPU include the manufacture of:

• hoses and pipes
• sports and industrial shoe soles
• cell phone covers and balls  

TPS - Thermoplastic styrene block copolymers 

Thermoplastic styrene block copolymers, TPS for short, belong to the group of polymer blends and are based on so-called styrene block copolymers (SBCs). These polymers typically consist of a soft middle block of polyethylene or polybutylene in between two hard end blocks of polystyrene. The combination of these structural building blocks gives TPS materials their particular flexibility and thermoplastic processability. 

TPS materials are extremely versatile and impress with their very good resistance to polar media such as water or acids. A special feature is the excellent adhesion to a large number of engineering thermoplastics, including polypropylene (PP), polyamide (PA), PC/ABS but as well substrates like SAN, ASA, PBT and POM. TPS also offer a very wide range of hardnesses - from particularly soft types with around 30 Shore 00 up to 60 Shore D. This range enables them to be used in a wide variety of applications. In addition, TPS can be specifically modified to meet special requirements such as UV resistance, increased flowability, flame retardancy, electrical conductivity or individual surface properties.

TPS are extremely user-friendly when it comes to processing. They can be excellently processed in both injection molding and extrusion. Thanks to their very good flow and adhesion properties, they are particularly suitable for multi-component applications, such as 2-component injection molding. 

Despite all their flexibility, TPS also reach their limits: When it comes to resistance to non-polar media and abrasion, standard TPS performs worse than TPU, for example. The clear strength of high-quality TPS is their versatility and individual modifiability according to customer requirements, making them the most versatile TPE class on the market.

Typical areas of application for TPS range from:

• ergonomic handles and seals to
• toys and
• sensitive applications in the medical sector. 

In the automotive sector, the material class can be found, for example, in storage mats and window encapsulation.

TPV - Thermoplastic cross-linked elastomers 

Thermoplastic vulcanizates, TPV for short, belong to the polymer blend material class and are usually based on a combination of ethylene-propylene-diene rubber (EPDM) and polypropylene (PP). This mixture is dynamically cross-linked during the manufacturing process.  

TPV-(EPDM+PP) are characterized by very good media resistance to polar substances such as water and acids. They are also UV-resistant and adhere to polypropylene, which makes them ideal for multi-component use with PP. The achievable hardness range extends from around 40 Shore A to 70 Shore D. TPVs can also be processed in both injection molding and extrusion. However, their high melt stability makes them particularly suitable for the extrusion process. When it comes to large-volume extrusion projects that require good compression set, but no specific modification requirements such as special colors, transparency or optimized mechanics, a high-quality TPV-(EPDM+PP) is usually the right choice.

TPV compounds are used in:

• seals 
• handles 
• plugs and technical profiles, as well as in 
• automotive applications, such as sealing systems or covers

If processors or customers require individual modifications, the choice of material often falls on a TPE class that allows more flexibility - TPS.

Conclusion: Not in a class of its own - but the right one for every application 

In view of the wide range of properties, it is important to consider a few crucial points to select a suitable TPE for your application:  

• Media contact 
• Temperature range of use 
• Adhesion to other components 
• Color 
• Mechanical load 
• Required market standards 
• UV stability 

This basic information can be used to find the right TPE material together with your trusted supplier.  Although TPU, TPV and TPS are sometimes used in similar fields of application, a direct comparison shows that each material class has specific strengths and limitations.  The optimal choice of material depends heavily on the specific application, but also on the material quality and the manufacturer's experience.

At KRAIBURG TPE, we offer more than just materials - we offer solutions. With in-depth expertise, custom-made compounds and honest advice, we help you find the right TPE for your application - and support you every step of the way, from the initial idea to series production. Let's develop the best solution together.