Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

Non-crimp fabrics based on flax yarn made by an innovative warp-knitting process

Flax pre-yarns with the optimal amount of twist from Almedahl spinning mill in Finland have been used for the manufacture of warp-knitted unidirection non-crimp fabric. In these fabrics all reinforcing fibres are oriented in one direction and knitted together to into a fabric by Engtex. The results obtained so far from tests at QMUL are very encouraging and clearly show the potential of such novel fabrics. Even in the case of relatively low fibre volume fractions of around 28% for the composites tested, because of the hand lay-up manufacturing method employed, the mechanical properties are already much higher than those of current state of the art non-woven flax fabric based composites.

Laminates with a fibre volume fraction of 28% exhibited strength of up to 190MPa and moduli of up to 16GPa. These values mean an increase in strength and stiffness of some 300-400% compared to non-woven flax composites. Even much higher values can be reached when higher fibre volume fractions are used as in vacuum infusion, pultrusion or resin transfer moulding processes. Since fibre volume fractions of 40-50% are typical for these processes strengths of 250 to 300Mpa seem feasible together with moduli of 20-28GPa! This result clearly shows the potential of the developed textile based composite materials as well as that the originally targeted strength value of 250Mpa is realistic and within the performance capability of the textile composites under development. Flax fibre laminates with strength values in the order of 250-300Mpa would be a major breakthrough as non-woven flax fibre composites have typical strength values of some 40-50Mpa!

Reported by

Queen Mary University of London
Mile End Road
E1 4NS London
United Kingdom
See on map