What is the difference between TPU and PU?

What is the difference between TPU and PU?

TPU (polyurethane elastomer)

TPU (Thermoplastic Polyurethane Elastomer) is an emerging plastic variety. Due to its good processability, weather resistance, and environmental friendliness, TPU is widely used in related industries such as shoe materials, pipes, films, rollers, cables, and wires.

Polyurethane thermoplastic elastomer, also known as thermoplastic polyurethane rubber, abbreviated as TPU, is a type of (AB) n-block linear polymer. A is a high molecular weight (1000-6000) polyester or polyether, and B is a diol containing 2-12 straight chain carbon atoms. The chemical structure between AB segments is diisocyanate, usually connected by MDI.

Thermoplastic polyurethane rubber relies on intermolecular hydrogen bonding or mild cross-linking between macromolecular chains, and these two cross-linking structures are reversible with increasing or decreasing temperature. In the molten or solution state, intermolecular forces weaken, and after cooling or solvent evaporation, strong intermolecular forces connect together, restoring the properties of the original solid.

Polyurethane thermoplastic elastomers can be classified into two types: polyester and polyether, with white irregular spherical or columnar particles and a relative density of 1.10-1.25. The polyether type has a lower relative density than the polyester type. The glass transition temperature of polyether type is 100.6-106.1 ℃, and that of polyester type is 108.9-122.8 ℃. The brittleness temperature of polyether type and polyester type is lower than -62 ℃, while the low temperature resistance of hard ether type is better than that of polyester type.

The outstanding characteristics of polyurethane thermoplastic elastomers are excellent wear resistance, excellent ozone resistance, high hardness, high strength, good elasticity, low temperature resistance, good oil resistance, chemical resistance, and environmental resistance. In humid environments, the hydrolysis stability of polyether esters far exceeds that of polyester types.

Polyurethane thermoplastic elastomers are non-toxic and odorless, soluble in solvents such as methyl ether, cyclohexanone, tetrahydrofuran, dioxane, and dimethylformamide, as well as in mixed solvents composed of toluene, ethyl acetate, butanone, and acetone in appropriate proportions. They exhibit a colorless and transparent state and have good storage stability.