Research on Pultrusion Molding of Carbon Fiber Composites Under Vacuum High and Low Temperature Environments

ABSTRACT Fiber‐reinforced thermoplastic composites, with excellent specific strength, specific stiffness, reprocessability and recyclability, are promising for on‐orbit fabrication of large truss structures. In this work, 2 mm‐diameter CF/PEEK rods were fabricated by pultrusion under vacuum with high‐low temperature boundary conditions. The effects of three key processing parameters (ambient temperature: −20°C to 50°C, forming temperature: 370°C to 390°C, pulling speed: 0.25 to 1.00 mm/s) on rod quality, flexural performance and crystallization behavior were systematically investigated. Within the studied parameter window, flexural strength decreased overall with increasing ambient temperature, forming temperature and pulling speed, with maximum reductions of 27.62%, 15.38%, and 27.80%, respectively. DSC results showed that higher crystallinity did not correspond to higher flexural strength. Combined with fracture morphologies, the results indicate that interfacial bonding state and cooling history‐governed shrinkage‐solidification process, rather than crystallinity alone, dominate the mechanical performance. Optimizing processing parameters to regulate cooling rate and improve consolidation in the effective holding zone can enhance rod performance, providing experimental guidance for prospective on‐orbit manufacturing.