Effects of process parameters on mechanical properties and interface of 3D printed bamboo-inspired CCFR-PLA/TPU composites

Inspired by the exceptional strength and toughness of fresh bamboo, a low-cost method for preparing continuous fiber-reinforced multi-matrix composites based on 3D printing was proposed in this paper. Through the design of a special extrusion nozzle, the controllable feed of polylactic-acid (PLA) and thermoplastic polyurethane (TPU) filaments was achieved, allowing for the preparation of continuous carbon fiber reinforced PLA/TPU composites. The effects of various process parameters on the tensile and flexural properties of the CCFR-PLA/TPU composites were investigated. Additionally, the relationship between process parameters and the formation of the matrix-fiber interface and PLA-TPU interface was analyzed. The results show that layer height has the greatest influence on mechanical properties, while the printing speed has the least influence. The mechanical properties of the CCFR-PLA/TPU composites and the unreinforced blend matrix, prepared using the optimal combination of process parameters, were tested. The results demonstrated that the tensile strength and flexural strength of the CCFR-PLA/TPU composites increased by 16.95 and 1.80 times, respectively, compared to the unreinforced blend matrix. Further, inspired by the overall structure of bamboo, a stiffness gradient CCFR composite material was designed and prepared. The methodology employed in this study holds significant implications for the advancement of novel multi-matrix hybrid continuous fiber reinforced composites, particularly in aerospace and related industries. Highlights: Multi-matrix continuous fiber reinforced composites were prepared by 3D printing inspired by fresh bamboo. The effects of process parameters (nozzle temperature, printing speed, extrusion width, layer height) on mechanical properties were investigated. The optimal printing parameter combination was determined by range analysis. Stiffness gradient composites were prepared inspired by the overall structure of bamboo.