New weft knitting process: Morphological, physical and mechanical characterisation of the innovative knitted fabrics

Abstract

A new knitting process is presented based on a novel yarn feeding technique. It allows the knitting of new structures: single jersey on one or both needle beds and rib structure on both needle beds in the same knitting cycle, that is the same needles. The innovative knitted fabrics were compared to standard 1 × 1 rib and plain woven fabrics made from the same material. All samples were tested for physical (grammage, air permeability), morphological (number of stitches per centimetre in wale and course directions and number of stitches per square centimetre, cover factor) and mechanical (uniaxial and multidirectional tensile behaviour) properties. Grammage was used as a reference parameter to render the results comparable. The results show that the innovative fabrics are less stretchable than the standard knitted fabrics, especially in the course direction, therefore more rigid in this direction. Furthermore, they can be mechanically balanced in course and wale directions, which is unexpected for knitted fabrics. The innovative knitted fabrics are thicker than the standard knitted fabrics for the same grammage and have a lower number of stitches per square centimetre, enabling higher production rates. Due to their lower cover factor, the innovative fabrics are expected to be easier to impregnate by resin for composite applications than the standard knitted fabrics. Based on these results and the ability to increase knitting productivity, we conclude that that this novel process can transform future processes and open the door to new markets and applications.