The influence of nanofibres in composite materials

Nanofibres have by definition a diameter less than 500 nm, which is several times smaller than the conventional fibres. Because of their very small fibre diameter these fibrous materials have specific and unique characteristics such as a high surface-to-volume ratio and high porosity. Thanks to this these nanofibres can be used in a broad spectrum of applications such as liquid and air filtration, wound bandages and composites. Although the literature on nanofibre composites is restricted, nanofibres can have advantages for advanced composites. Composites reinforced with conventional glass or carbon fibres may have very high tensile strengths, but the impact resistance is sometimes limited. A second problem of these actual composites is the delamination of the several textile layers. Both problems can be reduced by using nanofibrous webs between the glass or carbon layers. In our research large polyamide nanofibrous structures (PA 6, PA6.6, PA 4.6 and PA 6.9) were produced on a multi-nozzle setup. Starting from these structures the effect of the nanofibres on the curing of a epoxy matrix was investigated by thermo analytical measurements using a differential scanning calorimeter. Changing the nanofibres characteristics, especially the polyamide type and fibre diameter, will affect the curing behaviour of the resin. Furthermore the influence of the amount of water absorbed through the nanofibrous webs is inquired, by making identical composite samples at different relative humidity’s. In the second part of the research glass fibre/polyamide nanofibre composites were produced on large scale by infusion. The polyamide nanofibres were brought into the composites as stand-alone structures as well as coatings on the glass fabrics. The tenacity of these composites is compared to glass fibre composites without nanofibres. This research gives a good overview of the curing behaviour of the resin affected by the nanofibrous webs on the one side and the advantages of nanofibres for high performance composites on the other side