Abstract: Using linear density of 30 dtex and 50 dtex non-crimp fabrics as raw materials, the effect of linear density change of binding yarn on the properties of non-crimp fabrics involved in LCM process was investigated. The results show that the decrease of linear density of binding yarn is beneficial to improve the permeability of non-crimp fabrics. Metallographic pictures show that the binding yarn with lower linear density has a smaller volume and the fiber volume fraction at the binding yarn is smaller. The decrease of linear density of binding yarn is beneficial to slip and nesting between fibers, and the non-crimp fabrics can be compressed to a thinner thickness. In the range of 30 dtex to 50 dtex, the change of linear density of binding yarn has no obvious influence on the springback effect of non-crimp fabrics after deformation. When the binding yarn density is reduced from 50 dtex to 30 dtex, the 0° tensile strength decreased by 10.1%, the 0° compression strength increased by 21.9%, the bending strength increased by 9.5%, the interlaminar shear strength increased by 3.3%, the 0° tensile modulus increased by 6.3%, the 0° compression modulus increased by 11.3%, and the bending modulus increased by 9.9%. Metallographic pictures show that the interlaminar resin distribution of the composites prepared by 30 dtex binding yarn is easy to be nonuniform.

Key words: composites, liquid composite molding, non-crimp fabrics, binding yarn, mechanical property