TPU is usually medium to generally transparent, and some are milky white or turbid. Polyether TPU after adding long glass fiber is much more transparent than polyester TPU.

Through the thermal analysis of TPU grades, its performance in various applications can be measured. TPU relies on heat to obtain new shapes during extrusion and injection molding. Since multifunctional TPUs need to be heated repeatedly and sometimes combined with other materials to form high-performance composite materials with unique properties, detailed evaluation of the thermal properties of each TPU grade is crucial to predict its performance. The related thermal properties of TPU include thermal expansion, heat conduction, specific heat, combustion behavior (calorific value and calorific value) and thermal deformation temperature. Like all materials, TPU also has the property of thermal expansion and contraction. This phenomenon is expressed by the linear thermal expansion coefficient, which is a function of the temperature and the material's Shore hardness at the time of measurement. The thermal expansion performance of the glass fiber reinforced TPU grade is very interesting. Even if the glass fiber content is only 20%, the thermal expansion coefficient will be greatly reduced to a level similar to that of aluminum or steel, but the elastic modulus (Young's modulus) will not exceed 2000 MPa.