Compressive strength and thermal insulation properties of the 3D woven spacer composites with connected spacer yarn structure

The composite structures with lightweight, excellent mechanical and thermal properties are crucial to apply in the fields of industrial, civil as well as aerospace engineering. In this study, three-dimensional glass woven spacer fabric-reinforced epoxy resin composites (3DWSCs) were designed and manufactured. By increasing the interlacement of the pile yarn (IPY) from 2 to 6 ends/cm, the 3DWSCs presented similar light densities (0.3–0.42 g/cm3) but significant improvement in specific strength was from 3.9 to 24.6 MPa g−1 cm3, which is much higher than that of other reported 3DWSCs. This was because the pile yarns in the 3DWSC with dense IPY structure (6 ends/cm) were connected and supported with each other, and thus, their strength was fully utilized during compressive process. Contrary to the compressive strength, with the IPY increasing from 2 to 6 ends/cm, the thermal insulation of the 3DWSCs exhibited limited variation (~ 12.5%) and showed comparable performance with wood due to its high percentage of hollow structure (~ 75%). Therefore, the optimal 3DWSC structure (IPY is 6 ends/cm) with connected pile yarn structure exhibited excellent compressive strength as well as good thermal insulation, which showed great potentials in practical applications.