What is TPU (Thermoplastic Polyurethane)?
TPU is a polyurethane thermoplastic elastomer with high abrasion resistance, high elasticity and easy mouldability.
It is an ideal polymer for the applications of shoes, wires and cables, hoses and tubes, films and sheets, adhesives and custom molded parts.
Chemical Structure of TPU
TPU is created when a polyaddition reaction occurs between a diisocyanate and one or more diols. These materials can be as soft as rubbers or as rigid as plastics. This is achieved due to the presence of both rigid and soft segments in its chemical structure. While the soft segments are polyols, the rigid segments are isocyanates. Depending on the type of isocyanate, they can be classified as aliphatic or aromatic. The long flexible soft segment controls the low temperature operating characteristics, air resistance, solvent resistance and mechanical characteristics.
The rigid segment plays an important role in phase separation. Linear polymeric chains continue to overlap based on the following rule: due to differences in polarity, the soft segment matches with other soft segments, and rigid segments match with other rigid segments. It is possible to obtain products with very different rigidness, density and elasticity by changing the formulation.
Linear polymeric chains of TPU are in block copolymer structure.
Depending on their chemical structure and rigidness, soft TPUs (65 – 85 Shore A) have lower tensile strength, whereas rigid TPUs (50 – 70 Shore D) have higher tensile strength.
The most significant characteristics of TPUs are high abrasion resistance, high elasticity in wide temperature ranges and resistance to oils.
Usage Areas of TPU:
- Shoe soles
- Sensible Surface
- Ear Tags
- Industrial Wheels
- Hoses and tubes
- Protective containers
- Mining sieves
- Anti-slip chain
- Ski boots
Advantages of TPU:
- High abrasion resistance
- High elasticity
- High oil resistance
- High resistance to low temperatures
- High elasticity within wide rigidness and temperature range
- Low electrical conductivity
- High radiation resistance
Polyether-Based TPU (PTMEG)
- Very high hydrolytic stability
- Better breathability
- Flexibility at low temperatures
- Microbial resistance
- Resistance to weak acids and bases
- Lower densities
- Oil/solvent resistance
- Air (UV stab) resistance
- Very good resistance to weathering
- High heat resistance
- Superior mechanical properties