Effect of electrospun polyamide 6 nanofibres on the mechanical properties of a glass fibre/epoxy composite

Abstract

Recently, several types of nanoparticles are frequently incorporated in reinforced epoxy resin composites. A homogeneous dispersion of these nanoparticles is still a problem.Thermoplastic nanofibrous structures can tackle this dispersion issue. Therefore, this paper investigated the effect of electrospun polyamide 6 nanofibrous structures on the mechanical properties of a glass fibre/epoxy composite. The nanofibres were incorporated in the glass fibre/epoxy composite as stand-alone interlayered structures and directly spun on the glass fibre reinforcement. Both ways of nanofibre incorporation have no negative effect on the impregnation of the epoxy. Moreover, the nanofibres remain well dispersed within the matrix. Incorporation of nanofibres increases the stress at failure in the 0°-direction, the best results are obtained when the nanofibres are directly electrospun on the glass fibres. Optical microscopic images also demonstrate that nanofibres prevent delamination when a 90° crack reaches a neighbouring 0° ply. Furthermore, mode I tests showed a small improvement when a thin nanofibrous structure is deposited directly onto the glass fibres. When the composites are loaded under 45°, it is proven that, for an identical stress, the glass fibre composite with deposited nanofibres has less cracks than when interlayered nanofibrous structures are incorporated. Generally, it can be concluded that the addition of polyamide 6 nanofibres improves some mechanical characteristics of a glass fibre/epoxy composite.

Nanofibre bridging as a toughening mechanism in carbon/epoxy composite laminates interleaved with electrospun polyamide nanofibrous veils

“…Although Hamer et al report an increase in G Ic , only minor improvements and even decreases on both G Ic and G IIc are reported by Palazetti et al [18,20,21]. De Schoenmaker et al [14] state that G Ic increases slightly upon addition of PA 6 nanofibres in UD laminates. Furthermore, tensile tests on crossply laminates showed that the presence of PA 6 nanofibrous interlayers decreased or even stopped the formation of delaminations between reinforcing plies.…”

“…Uniform PA nanofibrous veils were produced by electrospinning on an in-house multinozzle system [14]. A linear lateral motion of the electrospinning nozzles perpendicular to the production direction guarantees the uniformity of the nanofibrous veils.…”

Electrospun nanofibers as reinforcement for composite laminates materials – A review

“…Three works in literature have been found dealing with tensile properties of nanomodified GFRP laminates, and they do not show the same agreement registered for carbon fibers. In [50] it is showed that tensile properties of UD GFRP laminates are not affected by the presence of PCL nanofiber; in [30], it is shown that PA6 nanofibers caused an increase of stress at failure of the composite of about 6% and 11% when the nanofibers were added during layup and when directly deposited onto the fabric, respectively. A unique use of Silk has been presented in [69], showing a 5% improved tensile strength.…”

“…In particular it has been observed that Poisson's ratio mismatches and edge effects have a significant role on the delamination resistance of composite laminates subjected to static and fatigue tensile loads, and it is the field of action of the nanofibers. In [30] it is suggested that nanofibers prevent or minimize the formation of delamination cracks between two fiber plies, and also demonstrated that the nanofibers facilitate the load transfer from the resin to the glass fibers. They also agree with results showed in [60], on the fact that the nanolayers create a matrix-enriched interlayer, which extensive deformation and slower growth of damage improve the tensile properties of the laminate.…”

Effect of PVDF nanofibers on the fracture behavior of composite laminates for high-speed woodworking machines

“…Up to now various kinds of polymeric nanofibers have been introduced by researchers for improving fracture toughness of composite laminates: Nylon 6 [13], Nylon 6,6 [14][15][16][17][18], Phenoxy [19], polyvinylidene difluoride (PVDF) [20][21][22], Polysulfone (PSF) [23], Polycaprolactone (PCL) [24][25]. Except PVDF, most other nanofibers have been investigated from different points of view.…”