Full definition
Polyurethane (PU) is a highly versatile elastomer that stands out due to its superior mechanical properties compared to other rubber materials. It exhibits exceptional abrasion resistance, which can be 3 to 10 times greater than that of natural rubber, making it ideal for applications where wear and tear are significant concerns. The tensile strength of polyurethane ranges between 30 and 70 MPa, and it offers outstanding tear resistance and high cut resistance, which is crucial in industrial settings where materials are subject to sharp edges and other damaging forces. The load-bearing capacity of PU is notable, allowing it to support heavy weights without compromising performance.
Available in a wide range of hardness from very soft (15 Shore A) to very hard (75 Shore D), polyurethane can mimic both rubber and rigid plastic, making it suitable for diverse applications. There are two primary chemical types of polyurethane: polyester-based (AU) and polyether-based (EU). Polyester-based PU typically offers better abrasion and oil resistance, while polyether-based PU excels in hydrolysis and microbial resistance, making the latter preferable in humid environments or applications exposed to water.
The operational temperature range for polyurethane is from -30°C to +80°C. However, it is essential to note that PU begins to degrade rapidly when exposed to temperatures above 80-90°C. The classification of PU under ASTM D2000 is BG, indicating its properties and suitability for specific applications. Common applications include conveyor belt scrapers, which benefit from its long wear life, industrial wheels and rollers that require high load capacity, hydraulic seals and wipers, screen panels for mining, pipeline pigs, vibration isolation pads, and protective coatings. Processing methods for PU include casting, which is standard for large parts using liquid systems, and injection molding, particularly for thermoplastic TPU, which is favored for high-volume production.