Thermoplastic elastomers

Thermoplastic elastomers (TPE): the elasticity of rubber with the processability of thermoplastics

Thermoplastic elastomers (TPE) are a group of polymer materials that combine the elastic behavior of elastomers with the ability to be processed by methods typical of thermoplastics: injection molding, extrusion, blow molding, coextrusion, and multi-component molding. Unlike conventional rubbers, most TPEs do not require vulcanization, which simplifies production, shortens the cycle time, and allows the material to be processed under more flexible processing conditions.

The engineering value of TPE goes beyond softness or elasticity. For a real part, what matters is Shore hardness, elastic recovery, compression set, fatigue endurance, flex resistance, behavior at low and elevated temperatures, adhesion to rigid polymers, contact with lubricants or detergents, color stability, surface feel, and the ability to reproduce these parameters consistently in series production.

TPE as a material platform, not a single polymer

The term TPE covers several different material families: TPE-S based on SEBS or SBS, TPU, TPEE, TPV, TPO, PEBA, and other elastomer systems. They may have the same Shore hardness yet differ radically in resistance to abrasion, oils, temperature, UV radiation, fatigue, chemical media, and behavior under prolonged compression.

That is why a thermoplastic elastomer cannot be selected on hardness or color alone. Two grades with the same 70 Shore A can perform in completely different ways: one will be better for a soft grip, another for a seal, a third for a cable jacket, and a fourth for a technical part requiring high fatigue endurance or contact with lubricants.

Main types of thermoplastic elastomers

TPE-S based on SEBS or SBS is often used in products that require softness, a pleasant tactile feel, good processability, colorability, and adhesion to PP or PE. These materials are used in grips, sealing elements, soft overlays, household products, packaging, and parts where a combination of elasticity and cost-efficiency is important.

TPU stands out for its high wear resistance, strength, tear resistance, good dynamic endurance, and ability to perform in technical parts where ordinary soft TPEs wear out quickly. It is often considered for rollers, wheels, sleeves, coatings, hoses, cable jackets, dampers, and parts operating in contact with abrasives or under mechanical load.

TPEE combines elastomeric behavior with higher heat resistance, fatigue strength, and stability under cyclic deformation. It is a material for bellows, resilient technical elements, hoses, cable jackets, and automotive and industrial equipment parts that require not just softness but long-term operation under dynamic load.

TPV and TPO are used where elasticity, better heat resistance, weather resistance, or behavior close to that of vulcanized rubber is required, combined with thermoplastic processability. The choice between these families depends on the requirements for temperature, environment, mechanical service life, surface, cost, and production technology.

Shore hardness and real elastic behavior

Shore A or Shore D hardness is one of the first parameters considered when selecting a TPE, but it does not describe the material's full behavior. Two grades with the same hardness can have different resilience, different compression set, different recovery after loading, different surface softness, and different behavior under repeated flexing.

For seals, dampers, flexible joints, grips, or overlays, you need to assess not only Shore hardness but also compression set, modulus at small strains, shape retention after compression, operating temperature, and load duration. A material that feels pleasant in a grip may perform poorly in a seal if it recovers its shape poorly after prolonged compression.

Adhesion to rigid polymers and 2K molding

One of the key advantages of thermoplastic elastomers is the ability to form a soft layer on a rigid substrate in two-component molding or overmolding. TPEs can be selected for adhesion to PP, PE, ABS, PC, PA, PBT, or other polymers, but compatibility always depends on the specific formulation, temperature, surface preparation, and molding conditions.

For soft overlays, grips, sealing zones, buttons, anti-slip surfaces, and housing parts of combined construction, not only elasticity but also the bond strength between the materials becomes critical. If adhesion is insufficient, the part may delaminate, lift at the edges, lose its sealing function, or behave inconsistently under flexing and friction.

Friction, wear, and surface feel

In many parts, TPE is assessed not only as a resilient material but also as a contact surface — with the hand, with another material, or with a moving assembly. For grips, buttons, overlays, support elements, wheels, rollers, and dampers, the coefficient of friction, surface dryness or “tackiness”, resistance to abrasion, soiling, fingerprints, dust, and aging of the surface layer are all important.

A material that is too soft may offer a pleasant tactile feel but pick up dirt faster, hold its shape less well, or wear more quickly. A material that is too hard may be more stable but lose the required damping effect or contact comfort. For technical parts, what matters is not maximum softness but the right balance between surface behavior, mechanics, service life, and processability.

Temperature, chemical environment, and long-term stability

Different TPE types differ significantly in temperature range and chemical resistance. SEBS compounds can perform well in soft household or packaging products, TPU withstands abrasion and mechanical load better, TPEE shows its strengths in dynamic applications and at elevated temperatures, and TPV can be the right choice for applications requiring heat resistance and weather resistance close to those of rubber systems.

Contact with lubricants, fuels, detergents, sweat, cosmetics, water, salts, or UV radiation can affect different TPE families in different ways. That is why the material for a seal, cable jacket, automotive part, medical component, tool grip, or exterior profile must be selected based on the actual environment, temperature, and expected service life.

Processing TPE by injection molding, extrusion, and coextrusion

Thermoplastic elastomers are processed on standard thermoplastics equipment, but each family has its own requirements for temperature profile, shear rate, pressure, cooling, drying, and melt stability. TPU and TPEE often require closer attention to drying, while SEBS compounds may be technologically simpler yet require the correct choice of carrier and compatibility with the base polymer.

In injection molding, flowability, stable filling of thin sections, absence of flash, surface quality, shrinkage, and demolding are important. In extrusion, the critical factors are profile stability, thickness uniformity, surface, gloss, blocking, shrinkage after cooling, and behavior during winding or subsequent assembly. In 2K molding and coextrusion, adhesion to the rigid polymer or to the adjacent layer is assessed separately.

Typical applications of thermoplastic elastomers

TPEs are used in products that require elasticity, elastic recovery, a soft surface, sealing, damping, or flexibility:

• seals, gaskets, sleeves, flexible inserts, and dampers;
• tool grips, soft overlays, anti-slip surfaces, and buttons;
• cable jackets, hoses, tubing, profiles, and coextruded products;
• wheels, rollers, support elements, shock-absorbing and vibration-isolating parts;
• soft components of household, medical, sports, and technical products;
• parts for 2K molding with adhesion to PP, ABS, PC, PA, PBT, or other polymers;
• elastic elements for automotive, industrial, and electrical applications;
• products where vulcanized rubber needs to be replaced with a thermoplastically processable material.

Critical parameters for TPE selection

To select the right thermoplastic elastomer, you need to assess not only Shore hardness but the full function of the part:

• TPE type: SEBS, SBS, TPU, TPEE, TPV, TPO, PEBA, or another system;
• Shore A or Shore D hardness and the actual elastic behavior;
• compression set and shape recovery after prolonged compression;
• fatigue endurance under flexing, stretching, or cyclic deformation;
• resistance to abrasion, friction, soiling, and surface aging;
• operating temperature range and low-temperature behavior;
• contact with lubricants, fuels, water, salts, sweat, cosmetics, or detergents;
• the need for UV stabilization, weather resistance, or color stability;
• adhesion to the rigid polymer in overmolding or 2K molding;
• processing method: injection molding, extrusion, coextrusion, blow molding, or a special technology;
• sanitary, food-contact, medical, or regulatory requirements, where relevant to the product;
• batch-to-batch consistency and repeatability of color, surface, and mechanical behavior.

When TPE is a better choice than rubber, PVC, or a soft polyolefin

TPE is often chosen instead of vulcanized rubber when a shorter cycle, processing on thermoplastic equipment, recyclability, more precise molding of small parts, 2K molding, or better integration with a rigid polymer housing is important. For many series products, this simplifies the production chain and reduces the number of operations.

Compared with PVC, some TPE systems can be preferable where softness without plasticizer migration, a different tactile feel, better elastic behavior, or specific regulatory requirements are needed. Compared with soft polyolefins, TPEs usually offer a wider range of elasticity, surface behavior, and modification options. At the same time, for high temperatures, aggressive media, or extreme service life, conventional rubber, TPU, TPEE, TPV, or specialty elastomers may each be more or less suitable — the decision depends on the part's operating conditions.

Thermoplastic elastomer selection by Material Wizard

Material Wizard selects thermoplastic elastomers not by the generic name TPE but by the actual function of the product. We analyze hardness, elastic recovery, compression set, contact environment, temperature, wear, surface feel, adhesion to rigid polymers, processing method, part geometry, and the economics of series production.

This approach makes it possible to choose a technically justified elastomer system: an SEBS compound for soft overlays, TPU for wear-resistant and strong parts, TPEE for dynamically loaded elements, TPV for heat- and weather-resistant products, or another specialty grade for specific conditions. For the manufacturer, this means not just a soft material but predictable part behavior in processing, assembly, and service.