A Study on the Effects of Carbon Fiber Type and Content on the Mechanical Properties of Carbon Fiber Reinforced Polyamide 6 Composites

Carbon fiber has become a revolutionary material in advanced manufacturing owing to its outstanding specific strength, specific modulus, low density, excellent wear resistance and corrosion resistance. As an important engineering plastic, polyamide 6 (PA6) has been continuously improved in performance and application scope with technological progress. By compounding carbon fiber with PA6, a new type of high‑strength, lightweight and corrosion‑resistant material can be prepared by combining the advantages of both components, which shows broad application prospects in automotive, aerospace, medical devices and other fields, and is also of great significance to environmental protection and sustainable development.

Mechanical test results show that the addition of carbon fiber significantly improves the tensile strength, flexural strength and flexural modulus of PA6. Neat PA6 exhibits a tensile strength of about 70 MPa, flexural strength of about 100 MPa, and flexural modulus of only 2.4 GPa. When reinforced with about 30 wt% T300 carbon fiber, the composite reaches a tensile strength of 166 MPa, 236.6% higher than that of neat PA6; the flexural strength is 224 MPa, increased by 229.6%; and the flexural modulus is 14.6 GPa, six times that of pure PA6. As for the notched impact strength, although it decreases after carbon fiber incorporation compared with neat PA6, it shows an upward trend with increasing fiber content, reaching a maximum of 7.18 kJ/m².

Microstructural morphology was observed via scanning electron microscopy (SEM) on impact fracture surfaces. The fracture surface of neat PA6 shows obvious wrinkles, while the fracture surfaces of composites become rougher with increased fiber content, accompanied by more fiber pull‑out and crack deflection. The fiber‑matrix interfacial wetting is satisfactory, and the resin can effectively encapsulate the fibers, which facilitates stress transfer. With increasing fiber content, fiber‑to‑fiber contact and interaction are enhanced, accompanied by partial fiber aggregation and entanglement.