Effect of Knitting and Finishing Parameters on the Initial Young’s Modulus and Tensile Strength for Polyester Weft Knitted Interlock Fabric

75D/72f and 100D/96f polyester yarns were knitted to develop three kinds of fabrics with different densities (large, medium and small) on circular knitting machine (gauge E18). It was found that the strength of the fabrics increased with the increase of loop density, and the initial modulus of the fabrics also increased. In order to obtain better strength and lower initial modulus, the washing and heat setting process of the fabric were studied and explored. The strength and initial modulus of the three density fabrics of the two yarn specifications decreased after pre-washing. Finally, the lowest initial modulus (0.36 MPa at warp direction and 0.22 MPa at weft direction) were found in sample (sample no. 3–3) made of 75D filament in longest loop length under 140 °C heat setting. The weft strength and warp strength were 9.54 MPa and 5.28 MPa respectively.