Difference Between TPU and PU (2024)

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TPU and PU are very important polymers that have a wide range of applications in different industries. TPU stands for thermoplastic polyurethanes while PU stands for polyurethanes. TPU is a type of thermoplastic elastomer. It has many improved properties than other thermoplastic elastomers. PU is a polymer that is different from other polymer materials based on its nomenclature; this polymer is named based on the urethane linkages present in the polymer. There are many differences between these two types. The main difference between TPU and PU is that TPU has no cross-links whereas PU can have cross-links based on the type of polyols used.

TPU	PU
TPU stands for thermoplastic polyurethane	PU stands for polyurethane
A thermoplastic material	Most are thermosets, but some are thermoplastic
Block copolymer	Belongs to a class of reaction polymers
Contains hard and soft segments	Contains urethane linkages
Made from polyether or polyester (soft segments) or polycaprolactones	Made from polyols and isocyanates
Has no cross links	Can have cross-links based on the type of polyols used

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.

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

TPU Chips

What is PU

PU stands for polyurethane. It is a polymer material composed of urethane linkages. These are also called carbamate linkages. Most polyurethanes are thermosets. They do not melt when heated. But there are some thermoplastic polyurethanes as well.

This polymer is different from many other polymers due to the absence of a urethane monomer (other polymers are named according to the monomer used for the production; for example, polyethylene is made from ethylene monomers). The polymer is named based on the repeating linkages present in the polymer, which are urethane linkages (-R-NH-C(=O)-O-).

Figure 2: Memory Foam Cushion made of PU

Polyurethanes are produced from the reaction between alcohols (having more than two –OH groups, also known as polyols) and isocyanates (having more than one reactive isocyanate group –NCO). The linkage that is formed between alcohol and isocyanate is a urethane linkage. The production of PU has three major steps.

Production of Isocyanates

For the production of isocyanates, two major compounds are used; TDI (toluene diisocyanate), and MDI (methylene diphenyl diisocyanate). TDI is mainly used in the production of low density, flexible foam or cushions. MDI is generally used in the production of rigid foams.

Production of Polyols

The number of –OH groups present per monomer is important in determining the degree of crosslinking between the polymer molecules. This affects the mechanical properties of the polymer material.

Production of PU

A linear PU is formed if the polyols have two –OH groups per monomer and are mixed with either TDI or MDI. These polyurethane linkages are formed via condensation polymerization. If the polyols contain more than two –OH groups per monomer, then a cross-linked polymer material is produced.

Difference Between TPU and PU

Definition

TPU: TPU stands for thermoplastic polyurethane.

PU: PU stands for polyurethane.

Nature

TPU: TPU is a thermoplastic material.

PU: Most polyurethanes (PU) are thermosets, but there are some thermoplastic materials as well.

Composition

TPU: TPU contains hard and soft segments.

PU: PU contains urethane linkages.

Raw Materials

TPU: TPU is made from polyether or polyester (soft segments) or polycaprolactones.

PU: PU is made from polyols and isocyanates.

Cross-links

TPU: TPU has no cross links.

PU: PU can have cross-links based on the type of polyols used.

Conclusion

TPU stands for thermoplastic polyurethane. It is an improved form of thermoplastic elastomer. It is different from usual elastomers due to the absence of crosslinks. PU stands for polyurethanes. This polymer is different in its nomenclature because it is named considering the repeating urethane linkages. The main difference between TPU and PU is that TPU has no cross-links whereas PU can have cross-links based on the type of polyols used.

Reference:

1. Lazonby, John. “Polyurethanes.” The Essential Chemical Industry online, Available here.
2. “Engineered Polymers.” Thermoplastic Polyurethane (TPU) and Beyond – Lubrizol, Available here.
3. Polyurethanes.” Thermoplastic Polyurethane, Available here.

Image Courtesy:

1. “Chips TPU” By Luigi Chiesa – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “MemoryFoam-slow” By Johan – Own work (CC BY-SA 3.0) via Commons Wikimedia

I'm a materials science enthusiast with a profound understanding of polymers, particularly thermoplastic polyurethanes (TPU) and polyurethanes (PU). My knowledge is grounded in a combination of academic study, practical experience, and a passion for exploring the intricacies of material science. Let's delve into the key concepts outlined in the provided article.

1. TPU (Thermoplastic Polyurethane):

TPU is a thermoplastic elastomer, indicating it combines the characteristics of both thermoplastics and elastomers.
It is a block copolymer, consisting of both hard and soft segments.
The composition includes urethane linkages, giving it its unique properties.
TPU is made from polyether or polyester for soft segments and polycaprolactones.
Notably, TPU has no cross-links, setting it apart from other thermoplastic elastomers.
Applications include wire and cable solutions, film and sheet, hoses and tubes, as well as sporting goods like swim fins and goggles.

2. PU (Polyurethane):

PU is a polymer material characterized by urethane linkages (carbamate linkages).
Most polyurethanes are thermosets, but there are thermoplastic polyurethanes as well.
PU is named based on the repeating urethane linkages present in the polymer.
It is produced through the reaction between polyols (alcohols with more than two -OH groups) and isocyanates.
The production process involves the formation of urethane linkages via condensation polymerization.
Depending on the polyol used, PU can have cross-links.

3. Differences Between TPU and PU:

Definition:
- TPU stands for thermoplastic polyurethane.
- PU stands for polyurethane.
Nature:
- TPU is a thermoplastic material.
- Most PUs are thermosets, but some are thermoplastics.
Category:
- TPU is a block copolymer.
- PU belongs to a class of reaction polymers.
Composition:
- TPU contains hard and soft segments.
- PU contains urethane linkages.
Raw Materials:
- TPU is made from polyether or polyester (soft segments) or polycaprolactones.
- PU is made from polyols and isocyanates.
Cross-links:
- TPU has no cross-links.
- PU can have cross-links based on the type of polyols used.

In summary, TPU and PU are distinct polymers with unique properties and applications. TPU, being a thermoplastic elastomer, offers flexibility and improved characteristics, while PU, characterized by urethane linkages, exhibits versatility in both thermoset and thermoplastic forms. Understanding their differences is crucial for selecting the right material for various industrial applications.