90A PU Sheet is an elastomer sheet with a specific hardness (Shore A hardness 90) made from polyurethane (PU) through a casting process. Polyurethane is a polymer material produced by the polymerization reaction of polyol and isocyanate. Its molecular chain contains both soft segments (flexible segments, usually polyether or polyester) and hard segments (rigid segments, formed by the reaction of isocyanate and chain extender). This unique "soft and hard segment block structure" gives it both the high elasticity of rubber and the high strength of plastic. 90A PU Sheet is a "medium-hard elastomer" that retains the elasticity and abrasion resistance of polyurethane while possessing high load-bearing capacity and dimensional stability. It is widely used in applications requiring "abrasion resistance, impact resistance, high resilience, and a certain degree of rigidity".
Core Performance Parameters and Advantages
1. Basic Physical Properties
- Hardness (Shore A): 90±2A (Medium to hard, between rubber and plastic)
- Density: 1.10-1.25 g/cm³ (Slightly higher than ordinary rubber and plastic)
- Color: Natural, black, brown
- Surface Finish: Smooth (fine surface finish with casting process), matte (some formulations), or textured (custom)
2. Mechanical Properties
- Tensile Strength: 25-40 MPa;
- Elongation at Break: 300%-500%;
- Tear Strength: 50-80 kN/m;
- Resilience: 40%-60%;
- Compression Set (70℃×22h, 25% compression): ≤15%-25% (Small deformation after long-term compression, maintaining support);
- Abrasion Resistance: Akron abrasion ≤0.05-0.1 cm³/1.61km.
Typical Applications: 90A PU sheets are used for components requiring "repeated friction, impact resistance, and no deformation" (such as conveyor belts, rollers, and anti-slip mats). Their high wear resistance and resilience significantly extend service life.
3. Wear Resistance
The molecular chain of polyurethane contains rigid benzene rings (from isocyanates) and flexible ether/ester bonds (from polyols), resulting in extremely low wear rates under dynamic friction environments. 90A hardness PU sheets, due to their moderate hardness (neither too soft to cause rapid wear nor too hard to lose cushioning), exhibit wear amounts only 1/3-1/5 that of rubber and less than 1/10 that of EVA when rubbed against surfaces such as sandpaper, metal, and rubber.
Typical Applications: Conveyor belt surface layer, industrial roller coating, elevator tread anti-slip layer, protective covers for mechanical parts (such as gear covers).
4. Chemical Resistance (Stable in Specific Media)
- Oil Resistance: Good short-term resistance to mineral oils (such as hydraulic oil, lubricating oil) and vegetable oils (such as engine oil). Long-term immersion may cause slight swelling (slight decrease in hardness but retention of function).
- Solvent Resistance: Stable to water and alcohols; however, sensitive to aromatic hydrocarbons, ketones, and esters (swelling or dissolving may occur; contact should be avoided).
- Acid and Alkali Resistance: Short-term stability to dilute hydrochloric acid, dilute sulfuric acid, and sodium hydroxide. Strong acids/alkalis may cause molecular chain degradation.
- Water Resistance: Low water absorption (≤0.5%). Minimal dimensional change after long-term immersion in water (but long-term high temperature and humidity may slightly affect performance).
- Note: 90A PU Sheet has better chemical resistance than ordinary rubber, but weaker than specialty plastics.
5. Temperature Resistance (Medium Temperature Stable)
- Long-term operating temperature: -30℃ to 80℃;
- Short-term withstand temperature: Up to 100-120℃;
- Low-temperature performance: Maintains some elasticity at -30℃, but extreme low temperatures (< -40℃) may cause hardening and brittleness.
Typical applications: Suitable for normal to moderate temperature environments (e.g., factory workshops, outdoor equipment). For higher temperature resistance, choose high-temperature modified PU (e.g., with added heat resistant agents, it can withstand 120-150℃).
6. Electrical Properties (Good Insulation)
- Voltage resistivity: 10¹²-10¹⁴ Ω·cm;
- Dielectric strength: ≥15 kV/mm (withstands low-voltage breakdown).
- Typical applications: Insulation protection for non-high-voltage electrical equipment.
