PA66 GF25 Tensile, Flexural & Creep Behavior

Glass-fiber-reinforced PA66 GF25 is one of the most widely used engineering thermoplastics in thermal-break profiles due to its high strength-to-weight ratio, dimensional stability, and superior mechanical performance. When used in aluminum window and façade systems, the material must withstand long-term mechanical loading, thermal cycling, and challenging environmental stresses. Understanding its tensile strength, flexural response, and creep resistance is essential for optimizing material selection, extrusion design, and long-term structural reliability.

1. Tensile and Flexural Strength Enhancement

Adding 25% glass fiber to PA66 significantly increases stiffness, tensile strength, and flexural modulus. Compared with unfilled polyamide, the reinforced structure exhibits lower deformation under load and better fatigue resistance. The fibers act as a load-bearing network, transferring mechanical forces more efficiently across the polymer matrix. This makes PA66 GF25 ideal for structural profiles that require consistent performance under static and dynamic loading.

2. Influence of Fiber Orientation and Processing

Mechanical properties depend strongly on fiber orientation generated during extrusion. When fibers align along the flow direction, stiffness and strength increase substantially. Proper screw design, melt homogeneity, and optimized shear conditions ensure that the fibers retain sufficient length during processing. Excessive shear can shorten fibers and create weak zones, reducing long-term reliability. Therefore, balanced shear and controlled extrusion parameters are essential for high-performance profiles.

3. Dimensional Accuracy and Cooling Behavior

Controlled cooling after extrusion stabilizes the polymer matrix and prevents internal stresses that may lead to warpage or dimensional variation. The cooling rate influences crystallization and molecular alignment, which directly affects stiffness and long-term stability. Precision calibration tables and uniform cooling channels help maintain dimensional tolerances required in thermal-break systems.

4. Creep Resistance for Thermal-Break Applications

Creep resistance is a decisive factor because thermal-break strips experience constant compression within aluminum frames. PA66 GF25 maintains its modulus and shape even under prolonged stress at elevated temperatures. The glass fibers significantly slow down creep deformation, providing long-term mechanical stability essential for maintaining insulation performance and preventing frame distortion.

Conclusion

PA66 GF25 offers an optimal balance of strength, stiffness, dimensional stability, and creep resistance, making it a preferred material in thermal-break and structural polymer applications. Through controlled extrusion, proper fiber orientation, and well-engineered cooling, manufacturers achieve profiles with consistent performance and long service life—helping improve energy efficiency and structural reliability in modern architectural systems.