Continuous Glass Fiber Reinforced Polyamide 6 Composite Melt Impregnation Pultrusion Molding: Effects of Processing Parameters and Die Geometry

ABSTRACT Polyamide6 (PA6) composites prepared by melt impregnation pultrusion face three challenges: low impregnation efficiency, thermo‐oxidative degradation, and fiber damage. To overcome these, a synergistic optimization strategy integrating processing control, structural design, and oxidation prevention was proposed. The impregnation index prediction model was refined to quantitatively evaluate the influence of coating angle and temperature on impregnation quality. A spreading roller system with a large coating angle ( θ ₀ = 76.85°) and rotational motion reduced porosity to 0.305%. The effects of processing and structural parameters on impregnation quality were systematically analyzed. Furthermore, a dynamic oxidation prevention strategy (NMIM) decreased oxidative degradation by 80%. Under optimal conditions (pultrusion speed = 50 mm/min, impregnation temperature = 245°C), the composites exhibited excellent properties: bending strength = 924.83 MPa, interlaminar shear strength = 78.86 MPa, and notched impact strength = 563.79 kJ/m ² .