Views: 1 Author: Site Editor Publish Time: 2025-08-14 Origin: Site
Thermoplastic polyurethane (TPU) is widely recognized for its excellent strength, elasticity, and elongation at break. By incorporating short glass fibers (SGF) into TPU to form composites, it is possible to combine TPU’s high elasticity with the high rigidity of glass fibers. This modification not only retains a certain level of flexibility but also significantly improves modulus, tensile strength, tear resistance, heat resistance, and dimensional stability. Moreover, these glass fiber reinforced TPU (GF-TPU) composites can be processed using conventional methods such as injection molding, extrusion, and calendering.
Research and Applications
In recent years, international research has focused on the structure–property relationships of GF-TPU. Manufacturers in Germany have successfully applied short fiber-reinforced TPU in producing motorcycle and automotive components.
Studies show that when glass short fibers are treated with a silane coupling agent and compounded with polyester-based TPU (Shore A hardness 85–90), the mechanical performance improves significantly. Adding 0.5 parts stearic acid (per 100 parts TPU) as a lubricant helps enhance processing efficiency.
The compounding process typically involves mastication of TPU, mixing with short fibers and stearic acid, sheet forming on a two-roll mill, and compression molding at 180 °C, followed by rapid cooling. Test specimens are cut both parallel and perpendicular to the calendering direction.
Key Findings
Fiber Breakage and Dispersion: During mixing, fibers may break. As the initial fiber length increases, dispersion improves, but breakage also increases.
Mechanical Performance:
Increasing fiber content significantly boosts stiffness. The stress–strain curve shifts from viscoelastic to predominantly elastic behavior.
Tensile strength is lowest at 11 parts fiber but rises steadily up to 67 parts.
Longitudinal tear strength improves with higher fiber content, while transverse tear strength decreases below 43 parts fiber, then partially recovers.
Notable anisotropy is observed, with longitudinal tear strength far exceeding transverse values.
Wear Resistance: Injection-molded TPU/SGF composites show reduced friction coefficient and wear rate with higher SGF content, reaching optimal performance at 40% fiber by weight. This makes them suitable for automotive bumper systems and other wear-critical applications.
Impact Resistance: Higher fiber content and Shore hardness reduce impact strength, particularly at low temperatures. Optimal design requires balancing fiber content and hardness for high-impact applications.
Aramid Fiber Reinforced TPU
In addition to glass fibers, short aramid fibers (0–30% content) have been melt-blended with TPU at 180 °C. While this reinforcement increases density and tensile strength (especially above 20% fiber), it reduces elongation at break and wear resistance. Aramid fibers also increase the apparent melt viscosity, particularly at low shear rates.
Conclusion
Glass fiber reinforced TPU composites offer a unique combination of high strength, rigidity, heat resistance, and wear resistance while maintaining good processability. Proper selection of fiber type, content, and TPU hardness is crucial for achieving the desired balance of impact resistance, mechanical properties, and process stability. These materials have strong potential in automotive, industrial, and consumer product applications, especially where injection molding and extrusion are required.
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