tpu (thermoplastic polyurethane) is a thermoplastic elastomer with excellent resistance to abrasion, oil lubrication and other compressive properties. TPU consists of a chain-like structure of soft and hard segments joined together, the number and properties of these segments may vary, resulting in tpu materials with varying degrees of hardness, from soft (Shore 30A) to very hard (Shore 100A). The material can therefore be used both as a soft engineering plastic and as a tough rubber.
TPU is widely used as an additive to reinforce other materials. For example, composites of TPU and polycarbonate or ABS. While pure TPU has a tensile strength of approximately 5076 psi (70A Shore), this material improves the flexural modulus to a maximum of 150,000 psi.
In addition to hardness, TPU can be manufactured from different base material compositions. There are three subgroups: polyesters, polyethers and polycaprolactones:
Polyester TPUs, are often recommended for the manufacture of parts that are susceptible to wear and tear. These materials have good chemical and lubricant resistance, are stable and have a wide range of applications in mixed materials.
Polyether TPUs are suitable for underwater applications. Features include excellent resistance to hydrolysis, resistance to microorganisms and tearing pressure, and the ability to remain flexible at low temperatures.
Polycaprolactone TPUs combine durability and toughness with excellent cold resistance and hydrolysis resistance and are successfully used in sealing applications.
TPU can exhibit high performance properties if processed through the correct injection moulding process. The material is non-abrasive and therefore does not require special coatings to be applied to the tools. Some manufacturers recommend pre-drying and post-treatment of defective parts as well. For the injection moulding of TPU, important factors are the temperature, pressure and plasticising energy of the mould and nozzle. If the injection moulding process or the design of the object does not match the material, this may lead to damage and shrinkage of the part. Despite the special conditions required for injection moulding, TPU parts are very popular in all industries and can be processed with conventional thermoplastic manufacturing equipment.
In conclusion, TPU is a material with many advantages and its unique structure and properties give it a wide range of potential for many applications.