## 1 Introduction  
Carbon fiber (CF) reinforced epoxy resin (EP) composites are widely used in aerospace, automotive, and electronic fields with its high specific strength, high specific modulus, high temperature, corrosion resistance, fatigue resistance, and a series of excellent performance [1; 2; 3]. However, it will cause varying degrees of damage to CF due to surface treatment. On the one hand, the impact resistance of composites will be decreased significantly. The interlaminar shear strength and toughness of composites will also be less improved. When EP is cured, its texture is brittle, causing the deterioration of its impact resistance and heat resistance [4; 5]. Carbon nanotubes (CNTs) have excellent mechanical properties and thermal stability because of their unique hollow tubular structure and nanoscale size, which are ideal for reinforcing materials of composites and can greatly improve the strength and toughness of polymer matrix composites [6]. Based on the fact that CF and CNTs can effectively improve the overall performance of EP, many performances of CNTs/CF/EP have been greatly improved when compared with CF/EP composite. [PERSON] et al. prepared carbon nanotube-modified CF/EP composite and found that the mechanical properties of the composite were improved in terms of rigidity and strength compared to the two-phase system [7]. [PERSON] et al. studied the effect of CNTs on the matrix cracks of the three-phase system, and found that the addition of CNTs significantly delayed the fracture of the matrix, resulting in the fracture toughness of the composites was increased by 40%, and the heat resistance was reduced, resulting in a delay in crack deformation of the matrix structure [8]. [PERSON] et al. prepared CNTs modified CF/EP composites, and the results showed that the flexural strength, T\({}_{\mathrm{g}}\) and heat distortion temperature of the three-phase system with 0.3 wt % CNTs were improved [9]. [PERSON] prepared CNTs/CF/EP composites by the freeze-drying process, and it was found that the freeze-drying method improved the dispersion effect of CNTs, which significantly improved the conductivity and flexural strength of composites as a result [10]. [PERSON] et al. found that the hierarchical glass fiber/epoxy resin composites with 0.5 wt % CNTs-AL\({}_{2}\)O\({}_{3}\) hybrid loading were observed to exhibit an improvement of 19% and 11% in flexural modulus and interlaminar shear strength, respectively. Moreover, the glass transition temperature was increased by 15 \({}^{\circ}\)C and the storage modulus at 50 \({}^{\circ}\)C was enhanced by 20% [11]. [PERSON] et al. prepared the electrodeposition of nanometer size polypyrrole layers on carbon fibers coated with multi-wall carbon nanotubes and found that the conductivity decreases with increasing polypyrrole thickness, but all the carbon nanotube-carbon fiber hybrids remain more conductive than pristine carbon fibers having a sizing coating [12]. [PERSON] prepared carbon nanotube/carbon fabric/epoxy composites by VARTM, and found that the composites increased by approximately 30% of the interlaminar shear strength as compared to that of carbon fiber/epoxy composites without carbon nanotubes and demonstrated significantly improved out-of-plane electrical conductivity [13]. Moreover, there are some researchers investigating the flame retardant and thermal properties of some additions of reinforced CFRP (Carbon Fiber Reinforced Polymer) composites. [PERSON] et al. fabricated flame-retardant carbon fibers decorated by bio-based polyelectrolyte complexes (PEC) consisting of chitosan (CH) and ammonium polyphosphate (APP), and its corresponding fire-retarded epoxy resin composites (EP/(PEC@CF)) were prepared. The resulting composites exhibited excellent flame retardancy as the limiting oxygen index (LOI) increased from 31.0% of EP/CF to 40.5% and UL-94 V-0 rating was achieved with only 8.1 wt % PEC [14].