Thermoplastic polyurethane (TPU) is widely used in hoses, tubes, cable jackets, footwear and industrial parts because of its flexibility, abrasion resistance and mechanical strength.
However, when TPU is used in water, hot water or high-humidity environments for long periods, hydrolysis resistance becomes an important factor.
For these applications, polyether TPU is usually preferred because of its better hydrolysis resistance.
What Is TPU Hydrolysis?
Hydrolysis is the degradation of a polymer caused by long-term exposure to moisture, especially when heat is also present.
If a TPU grade does not have sufficient hydrolysis resistance, long-term exposure may lead to:
- Loss of strength
- Reduced flexibility
- Surface cracking
- Lower mechanical performance
- Shorter service life
The combination of moisture + temperature + exposure time is especially important when evaluating TPU hydrolysis resistance.
Why Is Polyether TPU More Hydrolysis Resistant?
Both polyester TPU and polyether TPU offer good mechanical properties, but their resistance to water and humidity is different.
Polyester TPU is well known for excellent abrasion resistance, strength and processing performance.
Polyether TPU generally provides better resistance to:
- Hydrolysis
- Humidity
- Microbial attack
- Low-temperature environments
For products that remain in wet or humid conditions for long periods, polyether TPU is often a more suitable choice.
This does not mean polyester TPU cannot be used around water. The final choice should depend on the operating temperature, exposure time and specific TPU grade.
Polyether TPU vs Polyester TPU in Wet Environments
| Factor | Polyether TPU | Polyester TPU |
|---|---|---|
| Hydrolysis resistance | Generally better for long-term water or humidity exposure | May require stabilized grades for demanding wet conditions |
| Humidity resistance | Often preferred in tropical or humid environments | Suitable for many dry or moderate-use applications |
| Microbial resistance | Typically better for wet or biological environments | Can be more sensitive depending on formulation and exposure |
| Abrasion and strength | Good, depending on grade design | Often excellent and widely used in wear-resistant products |
| Typical wet-environment uses | Hoses, pneumatic tubes, cable jackets, outdoor flexible parts | Footwear, industrial parts and applications with controlled exposure |
Typical Applications of Hydrolysis-Resistant TPU
TPU Pneumatic Tubes and Hoses
Pneumatic tubes and industrial hoses may be exposed to moisture, compressed air and changing temperatures.
Polyether TPU can provide a good combination of hydrolysis resistance, flexibility, abrasion resistance and mechanical strength.
TPU Cable Jackets
Cables used outdoors or in humid industrial environments may need long-term protection against moisture.
Hydrolysis-resistant TPU helps maintain flexibility and durability under these conditions.
Depending on the application, UV resistance, oil resistance or flame retardancy may also be required.
Footwear and Outdoor Products
Footwear and outdoor components may experience rain, sweat and high humidity.
For products used in tropical or wet environments, hydrolysis resistance can improve long-term durability.
Hydrolysis Resistance Is Not the Same as Waterproofing
A material can prevent water penetration but still degrade after long-term exposure to moisture.
Hydrolysis resistance means the TPU can maintain its structure and mechanical properties in wet or humid conditions for a longer period.
When selecting TPU, consider not only whether the product contacts water, but also:
How long? At what temperature? Under what working conditions?
How to Choose Hydrolysis-Resistant TPU
Before choosing a TPU grade, consider four main factors:
Water exposure
Occasional contact or continuous exposure?
Temperature
Room-temperature water or hot water?
Processing method
Injection molding or extrusion?
Performance requirements
Hardness, flexibility, abrasion resistance and mechanical strength.
For long-term exposure to water or high humidity, polyether TPU is usually the preferred option.
Conclusion
Hydrolysis resistance is an important consideration for TPU products used in wet, humid or hot-water environments.
Polyether TPU generally offers better hydrolysis resistance and is widely used in pneumatic tubes, hoses, cable jackets, footwear and outdoor components.
Choosing the right TPU based on the actual operating environment can help improve product durability and service life.
For material selection support, contact Longyixing Chemicals with your application, processing method, temperature range and exposure conditions.
