Thermoplastic Elastomers (TPE) Explained

Thermoplastic elastomers (TPE) are found in toothbrush handles, automotive seals, and medical tubing. But what actually sets them apart from rubber and conventional plastics? An overview of their structure, classes, and processing—and what “recyclable” really means for TPE.

Thermoplastic elastomers do not fit neatly into any single category. This became apparent when international standards bodies tried to establish consistent names for them: Neither the nomenclature system for rubber (ISO 1629) nor the one for plastics (ISO 1043-1) was suitable. So a separate standard, ISO 18064, was developed jointly by rubber and plastics experts.

The current version, ISO 18064:2022 (DIN EN ISO 18064 in Germany), describes TPE essentially as follows: At service temperatures, they behave much like vulcanized rubber. At higher temperatures, however, they can be processed like thermoplastics—and more than once. This dual nature is precisely what matters when selecting a material.

The difference lies in crosslinking. Conventional rubber is vulcanized: Its molecular chains are chemically linked to form a permanent network. This makes it elastic, but the process cannot be reversed—once vulcanized, rubber can no longer be melted.

TPE work differently. They consist of hard and soft regions. The soft regions provide elasticity, while the hard regions hold the material together—but only through physical interactions, rather than permanent chemical bonds. When heated, these connections break down and the material becomes flowable. As it cools, it solidifies again.

TPV are a special case: They also contain chemically crosslinked rubber particles, but these are finely dispersed in a thermoplastic. This means the material can still be melted. Adjusting the ratio of hard to soft components allows its properties to be tailored.

• Easy processing: TPE are shaped by injection molding or extrusion, with no need for vulcanization.
• Less waste: Production scrap and rejected parts can be remelted and processed again.
• Heat limitations: Because the material is held together only by physical interactions, TPE soften at high temperatures. For continuous exposure to high temperatures or aggressive media, crosslinked rubber is often the better choice.

Recycling deserves a closer look. Unlike vulcanized rubber, TPE can be remelted. Clean, single-material production scrap can therefore be fed back into processing, depending on the material and quality requirements. However, this does not automatically mean that a TPE component will return to the material cycle as recycled material after use. Suitable collection, sorting, and reprocessing methods are needed. Recycling can be particularly challenging when TPE are firmly bonded to other materials in a component. Another key consideration is whether the recovered material meets the requirements of its next application.

“TPE” is an umbrella term. ISO 18064 divides TPE into seven classes based on their chemical composition. All abbreviations begin with TP:

1. TPA – Polyamide-based
2. TPC – Copolyester-based
3. TPO – Polyolefin-based
4. TPS – Styrene-based
5. TPU – Polyurethane-based
6. TPV – Thermoplastic vulcanizates: a thermoplastic containing finely dispersed, crosslinked rubber
7. TPZ – All other TPE

In practical applications, these three classes play a particularly important role:

TPS – the versatile option

They range from very soft to relatively hard. They offer good resistance to water and acids and adhere well to many other plastics. Standard TPS grades, however, have lower oil and abrasion resistance than TPU.

TPU – the tough option

They offer high strength, abrasion resistance, and resistance to oils and fuels. However, some grades are less resistant to water—especially hot water—and must be thoroughly dried before processing.

TPV – the sealing specialists

They usually consist of polypropylene and EPDM rubber, are UV-resistant, withstand water and acids, and are particularly well suited to extruded seals.

TPE are usually supplied as pellets and processed on the same injection molding machines as other plastics. According to TWI, cycle times as short as 20 seconds are possible in some cases. Some TPE, particularly TPU, must be carefully dried beforehand.

A particular strength is the combination of hard and soft materials: In two-component injection molding, the soft TPE is bonded directly to a rigid plastic part, for example, to create grippy surfaces or integrated seals. TPS are considered particularly suitable for this because they adhere well to many plastics.

Typical applications include:

• Automotive: Seals, window overmolding, airbag covers, bumpers
• Medical technology: Tubing, masks, resuscitation bags, syringe stoppers—increasingly as a replacement for PVC or rubber
• Consumer goods: Toothbrush handles, phone cases, toys, shoe soles
• Industry and construction: Hoses, cable jacketing, profiles, window and door seals

To select the right TPE, manufacturer KRAIBURG TPE recommends addressing the following key questions in advance:

• Which substances will the component come into contact with?
• What temperatures will it be exposed to?
• Does it need to adhere to other plastics?
• What are the requirements for mechanical loading, color, UV resistance, and compliance with standards?

The following TPE suppliers were among those represented at K 2025 in Düsseldorf:

• KRAIBURG TPE: TPS compounds, including THERMOLAST
• BASF: Elastollan TPU
• Covestro: Desmopan and Texin TPU
• Kuraray: Styrene-based TPE under the SEPTON brand

Whether in a toothbrush handle, an automotive seal, or a resuscitation bag, TPE rarely attract attention because they simply work. Even so, it is worth taking a closer look when selecting a material. The right class depends on the media, temperature, and adhesion requirements—and on whether the component needs to perform like rubber or be processed like a plastic. Addressing these questions early helps make the most of TPE’s dual nature.

Are TPE recyclable?
TPE can be remelted, so production scrap can be fed back into the process. Whether a component is recycled after use, however, depends on collection, sorting, and separation from other materials.

What is the difference between TPE and rubber?
Rubber is chemically crosslinked and cannot be remelted. TPE, on the other hand, are held together primarily by physical interactions: elastic during use and moldable when heated. However, they soften at high temperatures.

What do TPU, TPV, and TPS stand for?
These are abbreviations defined in ISO 18064: TPU stands for polyurethane-based TPE, TPV for thermoplastic vulcanizates, and TPS for styrene-based TPE. The other classes are TPA, TPC, TPO, and TPZ.