Abrasion resistance is one of the most important performance requirements for shoe soles, especially for footwear exposed to frequent friction, rough surfaces, and repeated movement.
Thermoplastic polyurethane (TPU) is widely used in shoe soles and outsoles because of its flexibility, mechanical strength, and wear resistance. However, not all TPU grades deliver the same abrasion performance.
Choosing the right TPU material, optimizing processing conditions, and improving outsole design can all help reduce premature wear.
1. Choose the Right TPU Grade
The selection of TPU grade is the first step toward improving abrasion resistance.
Both polyester-based and polyether-based TPU can be used in footwear applications, but their performance characteristics differ.
Polyester TPU is often selected for applications requiring high mechanical strength and abrasion resistance.
Polyether TPU is generally preferred when improved hydrolysis resistance and flexibility under humid conditions are important.
However, abrasion resistance depends on the complete material formulation, not simply whether the TPU is polyester- or polyether-based.
For shoe sole manufacturers, it is important to evaluate abrasion loss, tear strength, flexibility, and processing performance together.
2. Select an Appropriate TPU Hardness
TPU hardness is another important factor in outsole performance.
Harder TPU grades generally provide greater stiffness and support, while softer grades offer more flexibility and deformation under load.
However, higher hardness does not automatically mean better abrasion resistance.
Two TPU materials with the same Shore hardness may show different wear performance because of differences in polymer structure, formulation, and processing conditions.
For example:
Soft TPU grades (65A–80A): Suitable for applications requiring flexibility and a softer feel.
Medium-to-hard TPU grades (85A–95A): Commonly considered for outsoles requiring a balance of flexibility, support, and mechanical durability.
The appropriate hardness should be selected according to the footwear application and confirmed through actual abrasion testing.
3. Optimize TPU Injection Molding Conditions
Even a well-selected TPU grade may perform poorly if processing conditions are unsuitable.
Several processing factors deserve attention.
Proper Material Drying
TPU is hygroscopic, meaning it absorbs moisture from the surrounding environment.
Excessive moisture during processing can cause hydrolytic degradation, bubbles, surface defects, and reduced mechanical properties.
Before injection molding, TPU should be dried according to the supplier's recommendations, with moisture content controlled to the grade's specified limit.
Control Melt Temperature
Excessively high melt temperatures or long residence times may cause thermal degradation.
On the other hand, temperatures that are too low may result in incomplete filling or poor molding quality.
The processing temperature should be adjusted according to the TPU grade, machine configuration, and mold design.
Avoid Excessive Material Degradation
Repeated processing, excessive shear, and long residence times can affect polymer molecular weight and final product performance.
Maintaining stable processing conditions helps improve consistency between production batches.
4. Improve Shoe Sole Design
Abrasion resistance is not determined by material properties alone.
Outsole geometry and tread design also influence how wear develops during actual use.
Important design considerations include:
Tread pattern: A well-designed tread distributes contact forces and provides suitable traction.
Sole thickness: Sufficient thickness in high-wear areas can extend usable service life.
Contact pressure: Excessive localized pressure may accelerate wear.
Flexing areas: The outsole should accommodate repeated bending without developing cracks or premature damage.
For this reason, laboratory material testing should be combined with testing on finished shoe soles.
5. Test TPU Abrasion Resistance Correctly
Abrasion testing provides useful data when comparing different TPU grades.
Common test methods include:
ISO 4649 (DIN Abrasion Method)
This method measures rubber and elastomer abrasion resistance under standardized laboratory conditions. Results are commonly expressed as relative volume loss in mm3.
Under comparable test conditions, a lower volume loss generally indicates better abrasion resistance.
ISO 20871 (Footwear Outsole Abrasion Resistance)
This standard is specifically used to determine abrasion resistance in footwear outsoles.
When comparing materials, manufacturers should ensure that the same test method and conditions are used.
Laboratory abrasion results do not always directly predict real-world shoe sole durability, since actual wear also depends on surface conditions, temperature, loading, and footwear design.
6. Recommended TPU Materials for Shoe Soles
At Longyixing Chemicals, we offer TPU grades for different footwear manufacturing requirements.
Our shoe sole material range includes:
LYX-LA90 / LYX-LA95: TPU grades for shoe sole and outsole applications.
LYX-S65 / LYX-S70: Softer TPU options for footwear applications requiring greater flexibility.
LYX-1361: Another grade available for shoe sole applications.
The final grade selection should be based on the required hardness, abrasion performance, processing method, and finished-product testing.
We can provide technical data sheets and samples to support material evaluation.
Explore our TPU Shoe Sole Materials.
Conclusion
Improving abrasion resistance in TPU shoe soles requires more than simply choosing a harder material.
The best results come from combining suitable TPU grade selection, controlled processing conditions, appropriate outsole design, and standardized abrasion testing.
For shoe sole manufacturers looking to improve product durability, evaluating different TPU formulations under actual production conditions is an important step.
Looking for TPU materials for shoe soles and outsoles?
Contact Longyixing Chemicals for grade recommendations, technical data sheets, and samples.
