Thermoplastic polyurethanes
Thermoplastic polyurethanes (TPU) are a group of elastomeric (flexible) block copolymers based on urethane and ester or ether segments. Their hardness depends on the chemical structure of the copolymer and can vary from 60 Shore A to 74 Shore D. Typical hardness, as used for components of a conveyor system, is 95 Shore A.
TPU's flexibility, also at low temperatures, and excellent wear and crack resistance make these materials extremely suited to components of conveyor systems. For a short time TPU is usable at temperatures up to 110°C, but the temperature may not exceed 80°C over prolonged periods of time.
TPU absorbs roughly 0.2% moisture when saturated in water at 23°C and roughly 1.3% at 23°C/50% RH. This moisture absorption does not generally affect the mechanical properties and dimensional stability.
TPU is resistant to oils and aliphatic hydrocarbons. Unleaded petrol can make CPU swell somewhat as a result of the aromatic components of the fuel. TPU is not resistant to concentrated acids and alkalis, chlorinated and aromatic hydrocarbons, alcohols and warm water. TPU possesses excellent UV resistance.