Is polyurethane plus aramid fiber synchronous belt resistant to high temperature?

Polyurethane and aramid fiber timing belts combine the elasticity and wear resistance of polyurethane with the high strength and high-temperature resistance of aramid fiber, making them suitable for transmission systems operating under high-temperature conditions. The high-temperature resistance of aramid fiber (long-term operating temperature up to 200°C) significantly improves the heat resistance of timing belts, while the polyurethane matrix can also remain stable at high temperatures through modification. This article analyzes its high-temperature resistance in detail from four aspects: material properties, high-temperature resistance mechanisms, influencing factors, and optimization methods.

Material Properties and High-Temperature Resistance Mechanism

• Polyurethane Matrix Properties: The long-term operating temperature range of ordinary polyurethane is -40°C to 80°C, and it can withstand temperatures up to 100°C for short periods. Through modification (such as the addition of heat stabilizers), polyurethane's temperature resistance can be increased to 120°C-150°C. 2. Aramid Fiber Properties: Aramid fibers (such as Kevlar) have excellent high-temperature resistance, with long-term operating temperatures up to 200°C and short-term temperatures up to 250°C. Their thermal decomposition temperature exceeds 500°C, yet they maintain high strength (tensile strength approximately 3000 MPa) and high modulus (approximately 70 GPa) at high temperatures. 3. High-Temperature Resistance Mechanism: Aramid fibers, as the reinforcement layer, maintain high mechanical properties at high temperatures and bear the primary load. The modified polyurethane matrix utilizes heat stabilizers and a cross-linked structure to delay softening and decomposition at high temperatures.

• Key Factors Affecting High-Temperature Performance

1. Polyurethane Matrix Temperature Resistance

• Conventional polyurethane softens easily at high temperatures and requires modification to improve its temperature resistance.

• Adding heat stabilizers (such as antioxidants and UV absorbers) can delay high-temperature aging.

    2. Aramid Fiber Content and Distribution 

• Increasing the aramid fiber content improves the overall temperature resistance of the synchronous belt, but reduces flexibility.

• Uniform fiber distribution helps improve load transfer efficiency at high temperatures.

    3. Interfacial Bonding Strength 

• Poor interfacial bonding at high temperatures can lead to delamination and failure, requiring optimization through surface treatment (such as plasma treatment).

    4. Operating Conditions 

• Oxidation, moisture, and chemical agents in high-temperature environments can accelerate material aging, requiring comprehensive consideration of protective measures.

Methods and Applications for Improving High-Temperature Resistance

1. Polyurethane Matrix Modification: Add thermal stabilizers and crosslinkers to improve the heat resistance and thermal stability of polyurethane. 2. Optimize Fiber Content and Distribution: Rationally design the aramid fiber content (typically 30%-40%) to ensure its reinforcing effect at high temperatures. 3. Improve Interface Bonding: Surface treat the aramid fiber (e.g., with a silane coupling agent) to enhance the interfacial bonding strength with polyurethane. 4. Application Scenarios: ○ High-Temperature Drive Systems: Used in metallurgical equipment and drying equipment to withstand high-temperature environments. ○ High-Load Drives: Used in construction machinery and mining equipment to withstand high-temperature and high-load conditions. ○ High-Speed Drives: Used in textile machinery and printing equipment to maintain high-speed operation under high temperatures.

Summary: Polyurethane-aramid fiber timing belts significantly enhance high-temperature performance by leveraging the high-temperature stability of aramid fibers and the heat resistance of modified polyurethane. By optimizing fiber content, interfacial bonding, and matrix modification, their stability and service life in high-temperature environments can be further enhanced. Polyurethane-aramid fiber timing belts demonstrate exceptional performance in high-temperature transmission systems, high-load transmissions, and high-speed transmissions, providing a reliable solution for industrial transmissions operating under high-temperature conditions.