At present, a large number of waste textiles are disposed through incineration and burial, which cause serious environmental pollution. Therefore, recycling textile wastes into high mechanical products with eco-friendly method is an urgent issue. Based on the above status quo, three kinds of 3D waste denim fiber needled felts/epoxy composites (3DWECs) with different areal densities of the mono-layer fiber web were designed and fabricated, and the effect of the areal density of the mono-layer fiber web on its mechanical properties was studied in this work. The cross-section morphologies of 3DWECs were also examined. Tensile, bending and compressive test results revealed that 2# 3DWECs (the planar density of mono-layer fiber webs was 557 g/m2) possessed better mechanical properties than 1# 3DWECs and 3# 3DWECs. Both the static and dynamic mechanical testing results showed that 3D waste denim fiber needled felts acting as the reinforcement played an essential role in the bearing function. Moreover, the peel tests indicated that the peel strengths of the 3DWECs were above the limits of the Chinese National Standard for particle board. The composites have the potential as a substitute for some particle boards.

Two carbon/glass hybrid composites with different reinforced structures were designed and their mechanical and electromagnetic absorbing properties (EMAPs) were investigated in this paper. It was found that the tensile, bending, and double-notch shear strength of the three-dimensional (3D) quasi-isotropic (QI)-braided composite were 4.50%, 9.64%, and 14.29% higher than those of the QI-laminated composite, respectively. This was because Z-binder yarns in the 3D QI-braided composite can lock all yarn sets together to bear external stress and inhibit crack propagation in interlamination. The EMAPs of the 3D QI-braided composites were larger than that of the QI-laminated composite in the entire Ku band. This was because the Z-directional glass fibers in the 3D QI-braided composite were beneficial for electromagnetic transmission. The uniform arrangement of five sets of yarns (+45°, –45°, 90°, 0°, and Z-yarns) resulted in the 3D QI-braided composites having better QI-EMAPs and QI mechanical properties in plane and outstanding interlayer performance than the traditional carbon fiber laminated composite.