What is the difference between TPU and PU?
The full name of polyurethane is polyurethane, which is a high molecular compound containing a -NHCOO - unit in the molecular structure, the unit is formed by the reaction of isocyanate group and hydroxyl group, the reaction formula is as follows:      
-- N=C=O + HOˉ → -- NH-COOˉ       
In the 1970s, German Otto Bayer first synthesized PU. Around 1950, PU appeared in Europe as a textile finishing agent, but most of the solvent-based products were used for dry coating finishing. In the 1960s, due to the enhancement of people's environmental awareness and the introduction of government environmental regulations, water PU coating came into being. Since the 1970s, water PU coating has developed rapidly, and PU coated fabrics have been widely used. Since the 1980s, there has been a breakthrough in the research and application of PU. Compared with foreign countries, domestic research on PU textile finishing agent is relatively late.  & have spent      
Polyurethane coating agent is the main type of development today, its advantages are:      
Ø The coating is soft and flexible;        
Ø Good coating strength, can be used for very thin coating;        
Ø Porous coating, with moisture permeability and ventilation performance;        
Ø Wear-resistant, wet-resistant, dry-cleaning resistant.        
PU coating agents are classified by composition: polyester polyurethane; Polyether polyurethane; Aromatic isocyanate polyurethane; Aliphatic isocyanate polyurethane. According to the medium used on the use is divided into solvent and water class.      
TPU full name: thermoplastic elastomer copolymer, it is an environmentally friendly non-toxic new material, TPU can be divided into Polyester and Polyether class two categories, the products are widely used, TPU will be the product to replace PVC... This material softenes at a certain heat, but remains unchanged at room temperature.  
What is the molecular structure of TPU?                    
It is a linear polymer material formed by the reaction of diisocyanate, macromolecular polyol and chain extender. It is characterized by repeated carbamate groups in molecular composition, and contains urea formate, biuret, ester bond, ether bond and other groups. From the perspective of molecular structure, it is alternately composed of rigid chain segment and flexible chain segment, in which the rigid chain segment is obtained by the reaction of diisocyanate and chain extender, and the flexible chain segment is obtained by the reaction of diisocyanate and macromolecular polyol. This special molecular structure makes TPU have excellent properties incomparable to other types of thermoplastic elasticity.
Thermoplastic polyurethane elastomer (TPU) is an AnBm type block copolymer. There are urethane group and polyether group in TPU. The urethane group gathers together to form hard segment due to high cohesion energy, while the polyester or polyether group gathers together to form soft segment. The hard segment is incompatible with the soft segment, forming a microphase separation structure which is separated and connected with each other. Due to the unique soft and hard segment microstructure of TPU, the macroscopic physical properties of the material are very outstanding, mainly reflected in the following aspects: 1. Excellent elongation, high tensile strength;
2. Excellent elastic recovery and good flexibility;
3. Good waterproof and moisture permeability;
4. Good biocompatibility;
5. Excellent resistance to wear, buckling and low temperature;
6. Excellent oil resistance and UV radiation resistance.
Seven. Good post-processing properties
8. Meet environmental requirements
The difference between TPU and PU
PU (thermoplastic polyurethane elastomer) is an emerging plastic variety, because TPU has good processability, weather resistance, environmental protection, is widely used in footwear, pipe, film, roller, cable and wire and other related industries. Polyurethane thermoplastic elastomer, also known as thermoplastic polyurethane rubber, referred to as TPU, is A (AB) N-type block linear polymer, A is a high molecular weight (1000-6000) polyester or polyether, B is a diol containing 2-12 straight chain carbon atoms, the chemical structure between AB segments is diisocyanate, usually MDI connection. The general structural formula is shown in the figure. Thermoplastic polyurethane rubber is cross-linked by intermolecular hydrogen bonds or slight cross-linking between macromolecular chains. With the increase or decrease of temperature, these two cross-linking structures are reversible. In the molten state or solution state, the intermolecular force is weakened, and after cooling or solvent volatilization, there is a strong intermolecular force connected together to restore the performance of the original solid.
Polyurethane thermoplastic elastomers are polyester type and polyether type two types, white irregular spherical or columnar particles, the relative density of 1.10-1.25, polyether type relative density is smaller than polyester type. The glass transition temperature of polyether type is 100.6-106.1 ℃, and the glass transition temperature of polyester type is 108.9-122.8 ℃. The brittleness temperature of polyether type and polyester type is lower than -62℃, and the low temperature resistance of hard ether type is worse than that of polyester type.
Polyurethane thermoplastic elastomers are characterized by excellent wear resistance, excellent ozone resistance, high hardness, high strength, good elasticity, low temperature resistance, good oil resistance, chemical resistance and environmental resistance, and the hydrolysis stability of polyether ester in wet environment is far more than that of polyester type.
Polyurethane thermoplastic elastomer is non-toxic, odorless, soluble in methyl ethyl ligand, cyclohexanone, tetrahydrofuran, dioxane, dimethylformamide and other solvents, can also dissolve in toluene, ethyl acetate, butyl ketone, acetone in the appropriate proportion of the mixed solvent, colorless and transparent state, has good storage stability.
PU polyurethane is a general term for polymer compounds formed by the reaction of diisocyanate or polyisocyanate with more than two hydroxyl groups, and its main chain contains many repeated NHCOO groups. Commonly used diisocyanates are toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexyl diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), polymethylene polyphenyl polyisocyanate (PAPI), benzene dimethylene diisocyanate (XDI) and so on. According to the different hydroxyl components used, it can be divided into polyester type and polyether type. It can be used in the manufacture of plastic products, wear-resistant synthetic rubber products, synthetic fibers, hard and soft foam products, adhesives and coatings.
TPU and PU are essentially made up of the same material. But when you're making these two kinds of glue. They don't use the same formula. These two kinds of rubber materials are divided into many kinds of properties. The characteristics of the rubber compound made by different formulas are not the same. These properties refer to both mechanical and physical properties.