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The ablation mechanism and performance of carbon fiber (CF)-reinforced poly aryl ether ketone (PAEK) thermoplastic composites were studied in this paper. The results show that the ablation damaged area is controlled by the irradiation energy, while the mass loss rate is controlled by the irradiation power density. In the ablation center, the PAEK resin and CFs underwent decomposition and sublimation in an anaerobic environment. In the transition zone, the resin experienced decomposition and remelting in an aerobic environment, and massive char leaves were present in the cross section. In the heat-affected zone, only remelting of the resin was observed. The fusion and decomposition of the resin caused delamination and pores in the composites. Moreover, oxygen appeared crucial to the ablation morphology of CFs. In an aerobic environment, a regular cross section formed, while in an anaerobic environment, a cortex–core structure formed. The cortex–core structure of CF inside the ablation pit was caused by the inhomogeneity of fibers along the radial direction and the residual carbon layer generated by resin decomposition in an anoxic environment. The description of the ablation mechanism presented in this study broadens our understanding of damage evolution in thermoplastic composites subjected to high-energy CW laser irradiation.

This work concentrated on the interlaminar mechanical properties and toughening mechanism of carbon fiber-reinforced bismaleimide resin (CF/BMI) composites modified by polyacrylonitrile (PAN) nanofiber films. The PAN nanofiber films were prepared by electrospinning. End-notched flexure (ENF) and short-beam strength tests were conducted to assess the mode II fracture toughness (GIIc) and interlaminar shear strength (ILSS). The results showed that the GIIc and ILSS of PAN-modified specimens are 1900.4 J/m2 and 93.1 MPa, which was 21.4% and 5.4% higher than that of the virgin specimens (1565.5 J/m2 and 88.3 MPa), respectively. The scanning electron microscopy (SEM) images of the fracture surface revealed that the PAN nanofiber films toughen the composite on two scales. On the mesoscopic scale, the composite laminates modified by PAN formed a resin-rich layer with high strength and toughness, which made the crack propagate across the layers. At the microscopic scale, the crack propagation between two-dimensional nanofiber films led to constant pull-out and breakage of the nanofibers. As a result, the interlaminar fracture toughness of the composite laminates improved.