Temperature-dependent mechanical properties and material modifications of carbon fiber composites for optimized structures in high-end industrial applications

This review investigates the mechanical performance and environmental durability of carbon fiber-reinforced polymer composites, covering thermoplastic (e.g., CF/PEKK) and thermoset (e.g., carbon/epoxy) systems under varying temperature, mechanical, and geometric conditions, while highlighting advanced material modification strategies. At cryogenic temperatures, CF/PEKK composites demonstrate notable improvements in interlaminar shear strength (up to 42 % at −196 °C), tensile strength (2403 MPa vs. 2274 MPa at RT), and flexural modulus (142 GPa at −196 °C), driven by matrix stiffening and improved fiber-matrix interactions, making them promising for aerospace and cryogenic applications. Pre-bending induces micro-cracking, reducing flexural modulus by up to 24 %, though low temperatures mitigate the damage. CF/PEKK composites also show robust Mode II toughness (4800 J/m²). Interfacial engineering, such as thermoplastic film interleaving (PEI, PEEK), significantly enhances fracture toughness in thermoset composites, with PEEK-modified laminates achieving a 248 % increase in Mode I initiation toughness (1600 J/m²). Geometric optimization improves joint performance; CF/PEKK bolted joints with a width-to-hole diameter (W/D) ratio of 4 attain a bearing strength of ∼900 MPa at low temperatures, while higher W/D ratios shift failure modes and increase peak loads by 65.4 % (5.08 kN). Incorporating 0.5 wt% halloysite nanotubes (HNTs) to PEI adhesives improves lap shear strength by 12.5 %. Similarly, amorphous HNTs into carbon/epoxy composites reduces moisture absorption by 66 % and boosts flexural strength (3141 MPa). These findings underscore the critical role of strategic material selection, processing optimization, and fiber-matrix interface engineering in maximizing composite performance. Future work should explore bio-based matrices, nanomaterials, and 3D printing for greater sustainability and performance.