Effects of Nylon 6,6 nanofibrous mats on thermal properties and delamination behavior of high performance CFRP laminates

Abstract

Nylon 6,6 electrospun nanofibrous membranes interleaved in "high performance" Carbon Fiber Reinforced Polymer (CFRP) laminates have been proposed as a means to provide a high threshold value to delamination on structural sites where composites are more prone to develop such failure. A model, highly crosslinked, thus inherently brittle, epoxy matrix was selected for its high Young's modulus and glass transition temperature exceeding 250 C. The influence of the Nylon 6,6 nanofibers on the curing behavior of the matrix and on the thermal and dynamic mechanical properties of the cured resin was investigated. These properties were related to the features of the epoxy resin and of the resin impregnated nanofibrous mat. Finally, the delamination behavior of the composite laminates interleaved with Nylon interleaves with different thicknesses was studied through Mode I delamination tests on Double Cantilever Beam (DCB) samples. The results show that the initial Mode I fracture toughness was increased up to about 50% by the presence of the thin mat interleaf. POLYM. COMPOS., 36:1303-1313, 2015

Electrospun nanofibers as reinforcement for composite laminates materials – A review

“…The main issues with the use of CNT and CNF are linked to health dangerousness [85] and difficulties in mixing and homogenizing with the matrix [86]. Authors considered out of the scope of this literature, and therefore did not treat, studies on nanofibers embedded in pure matrix [60,[87][88][89][90][91][92][93][94], on the single nanofiber [95][96][97][98], and on numerical simulations of nanomodified composites [65,[99][100][101][102].…”

“…• resin reinforcement [23,60,[87][88][89][90][91][92][93][94], detected by several authors, using a different type of polymers. In [94] it is demonstrated that using an hybrid electrospinning-electrospraying method (electrospraying uses polymers with much shorter chains which end deposited as particles rather than fibers), a resin containing 0.13% weight content of fiber was 700% stronger, 250% stiffer, and more ductile than the non-modified one.…”

“…As mentioned by few authors [89,91,93], a main aspect to take into consideration when interleaving nanofibers in a laminate is their adhesion with the resin: it is affected by several factors (moisture of the nanofibers, process conditions such as pressure, temperature, and vacuum grade, etc.) and strongly influences the final performances of the laminate.…”

“…• crack path modification [37,39,45,62,93], observed mainly when using PA nanofibers, but also with phenoxy, PCL and PSF. Those papers investigating the crack path during delamination propagation, discovered that the presence of nanofibers hinders the motion of the crack, which is then forced to follow tortuous path, thus increasing the energy required to propagate, compared with a neat interface.…”

Supervised and non-supervised AE data classification of nanomodified CFRP during DCB tests

“…As some of the authors have already demonstrated, interleaving small diameter fibres between one or more interfaces improves strength, toughness and delamination resistance of composites without reducing the in-plane properties or adding weight [2][3][4][5][6][7].…”