Difference Between TPE and TPU

Main Difference – TPE vs TPU

Thermoplastic elastomers or TPE are polymer materials that are elastomers, but they are not thermosets like normal elastomers. These are thermoplastics. Hence, these materials do not need any curing or vulcanization processes. TPU stands for thermoplastic polyurethane, and it is a form of TPE. TPU has more improved properties than other TPE materials. The main difference between TPE and TPU is that TPE burns with a faint aroma whereas TPU burns with an irritating odor.

Key Areas Covered

1. What is TPE
– Definition, Favorable Properties, Drawbacks
2. What is TPU
– Definition, Properties, Applications
3. What are the Similarities Between TPE and TPU
– Outline of Common Features
4. What is the Difference Between TPE and TPU
– Comparison of Key Differences

Key Terms: Copolymer, Elastomers, Monomers, Rubber, Thermoplastic, Thermoplastic Elastomers, Thermoplastic Polyurethane, Thermosets, Vulcanization

What is TPE

TPE stands for Thermoplastic Elastomers. These polymers are also called thermoplastic rubbers. They are a class of copolymers. A copolymer is a polymer made from more than one type of monomers. Most elastomers are thermosets, but TPE is thermoplastic. Therefore, these materials do not need any curing or vulcanization processes, unlike thermoset elastomers. TPE can be stretched repeatedly without any permanent deformation.

TPE is a rubber-like material. This material can be easily processed via thermoplastic technologies such as injection moulding, extrusion, etc. TPE is made by adding suitable components such as oil, fillers to a soft rubber material. These components are known as additives.

Figure 1: Thermoplastic Elastomer vs Thermoset Elastomer

TPE has replaced most other types of rubber materials in the automotive industry due to its favorable properties. Some of these properties include good processability, colorability, chemical resistance, softness, recyclability, and good flexibility. Some examples of TPE include the followings.

TPE-s (Styrenic block copolymers)
TPE-o (Thermoplastic polyolefinelastomers)
TPE-v (Thermoplastic Vulcanizates)
TPE-E (Thermoplastic copolyester)

However, there are some drawbacks of TPE as well; the material is highly expensive due to high cost in processing, and it is more temperature sensitive than other elastomers. The durability of TPE is also relatively low.

What is TPU

TPU stands for Thermoplastic Polyurethane. It is a type of thermoplastic elastomer. Hence, it is elastic and melt-processable. It has many favorable properties such as elasticity, transparency, resistance towards oils and abrasion resistance. TPU is a form of block copolymer (contains soft and hard segments).

TPU can be colored through a number of processes, and it is also extremely flexible. This is mainly due to the composition of hard and soft segments. The hard parts are either aromatic or aliphatic. They are generally aromatic, but the aliphatic hard segments are preferable when the color and clarity retention in exposure to sunlight is more important.

Figure 2: TPU Chips

The oil resistance arises with the soft segment of this block copolymer. The soft segments are often either polyether or polyester types, but this depends on the application. Polyether soft segments are important to withstand wet environments whereas polyester soft segments are important in oil resistance. Some applications of TPU are given below.

Wire and cable solutions – provide toughness and flexibility along with extended durability
Film and sheet – provide durability and flexibility
Hose and tubes
Sporting goods swim fins and goggles

However, TPU has a high hardness when compared to other types of thermoplastic elastomers. When burnt, TPU burns with an irritating odor. The products made of TPU feel rougher and has high friction.

Similarities Between TPE and TPU

Both are thermoplastic polymer materials.
Both are types of elastomers.
Both materials are temperature sensitive.

Definition

TPE: TPE stands for thermoplastic elastomers.

TPU: TPU stands for thermoplastic polyurethane.

Hardness

TPE: Most TPE materials have a less hardness.

TPU: TPU has a high hardness.

Burning

TPE: TPE burns with a faint aroma.

TPU: TPU burns with an irritating odor.

Feel

TPE: TPE is soft and feels more delicate.

TPU: TPU products feel rougher with strong friction.

Chemical Resistance

TPE: TPE has a moderate resistance towards chemicals.

TPU: TPU has a high chemical resistance.

Abrasion Resistance

TPE: TPE has a moderate abrasion resistance.

TPU: TPU has high abrasion resistance.

Conclusion

Both TPE and TPU are thermoplastic polymer materials. The main difference between TPE and TPU is that TPE burns with a faint, aroma whereas TPU burns with an irritating odor.

Reference:

1. “Thermoplastic Elastomer (TPE) Plastic.” UL Prospector, Available here.
2. “Thermoplastic elastomer.” Wikipedia, Wikimedia Foundation, 10 Feb. 2018, Available here.
3. “Polyurethanes.” Thermoplastic Polyurethane, Available here.

Image Courtesy:

1. “Thermoplastic elastomer TPE” By LaurensvanLieshout – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “TPU texture” By Luigi Chiesa – Own work (CC BY-SA 3.0) via Commons Wikimedia