ETPU (Expanded Thermoplastic Polyurethane) can be understood as a lightweight, highly resilient “popcorn” material. Through physical foaming technology, countless closed micro-cells are formed inside the TPU, combining the high toughness, abrasion resistance, and low-temperature resistance of TPU with the ultra-lightweight and high-cushioning advantages of foam.
Core Performance and Typical Parameters
The performance of ETPU is highly dependent on its molded density and base TPU formulation. Here are the typical ranges for its key parameters:
| Parameter | Typical Range / Value | Test Standard Reference | Description |
|---|---|---|---|
| Molded Density | 0.08 – 0.35 g/cm³ (80–350 kg/m³) | ASTM D792 / ISO 2781 | Extremely low density is the key to lightweighting; adjustable via expansion ratio. |
| Hardness (Asker C / Shore A) | Asker C 35 – 52 or Shore A 35 – 55 | ASTM D2240 | From soft to medium-hard, adapting to different cushioning needs. |
| Rebound Resilience | > 60% – 78% (Ball Rebound / Pendulum) | ISO 8307 / ASTM D2632 | A core advantage of ETPU, far higher than traditional EVA (approx. 55-65%), efficiently returning energy. |
| Compression Set | < 5% – 15% (at room temp) | ASTM D395 / ISO 1856 | Excellent resistance to long-term compression, meaning the material resists “bottoming out” after repeated stress. |
| Tensile Strength | 1.3 – 8 MPa | ASTM D412 / DIN EN ISO 1798 | Wide range depending on density and formulation. |
| Tear Strength | 1.0 – 5 kN/m | ASTM D624 | Reflects the material’s ability to resist tear propagation. |
| Low-Temp Resistance | Stable performance at -20℃ to -30℃ | — | Retains elasticity and softness in extreme cold without embrittlement. |
| Fatigue/Bending Resistance | > 120,000 flex cycles without cracking | — | Outstanding dynamic durability, suitable for high-frequency, long-cycle applications. |
Main Applications
ETPU applications are expanding from footwear to diversified fields:
- Footwear (Core Application): The most well-known application, used as sports shoe midsoles (e.g., “popcorn” technology), providing lightweight, high-rebound, durable, and cold-resistant cushioning.
- Sports Protection & Leisure: Utilized for its excellent energy absorption and cushioning in sports protectors, bicycle saddles, grips, mattresses, and padding.
- Automotive Industry: Used for interior components, sound insulation, and vibration damping elements, aligning with the lightweight trend of electric vehicles.
- Industrial & Specialty Applications: Includes low-load non-pneumatic tires, running tracks/sports surfaces, and packaging cushioning materials.
Key Testing Standards
Evaluating ETPU performance requires referencing a series of physical property testing standards:
- Density: ASTM D792 or ISO 2781.
- Hardness: ASTM D2240 or ISO 7619-1 (often using Shore A or Asker C scales).
- Rebound Resilience: ISO 8307 (ball rebound) or DIN 53512 (pendulum).
- Compression Set: ASTM D395 or ISO 1856 (e.g., 50% compression at 70°C for 22 hours).
- Tensile/Tear Strength: ASTM D412 / ASTM D624.
- Dynamic Fatigue: Evaluated through high-frequency compression tests (e.g., 100,000 cycles) to assess performance degradation.
Material Selection Advice
When selecting ETPU, balance the following key dimensions based on the core requirements of the final application:
- Density vs. Performance: Lower density means lighter weight but usually sacrifices some tensile and tear strength. Find the balance between lightweighting and durability.
- Hardness vs. Rebound: Hardness determines the softness and support. High rebound (>70%) is ETPU’s advantage, but specific grades should be selected based on hardness requirements.
- Temperature & Weathering: For extreme cold applications (e.g., outdoor gear, cold-region automotive parts), prioritize low-temperature flexibility and rebound retention. For long-term outdoor exposure, also consider anti-yellowing grades (e.g., QUV testing).
- Processing & Sustainability: ETPU is mainly supplied as foamed beads, molded via steam chest molding or injection molding. Look for suppliers offering bio-based or recycled content grades to meet environmental regulations or brand goals.
About Yantai Linghua New Material Co., Ltd.
As a professional TPU manufacturer with a strong R&D foundation, Yantai Linghua New Material Co., Ltd. has extensive expertise in the modification and production of thermoplastic polyurethane. Leveraging our advanced material formulation capabilities, we can provide high-performance base TPU resins specifically tailored for the ETPU foaming process. Whether you need customized hardness, enhanced low-temperature toughness, or specific melting characteristics for bead foaming, Linghua New Material is committed to providing reliable raw material solutions to empower your ETPU innovations.
Post time: Oct-28-2026