Study on Mode I fatigue behaviour of Nylon 6,6 nanoreinforced CFRP laminates

Abstract

The benefits of interleaving polymeric electrospun nanofibers in between laminae of composite structure have been widely demonstrated in the past several years. Among the work that still has to be done, this paper aims to study delamination propagation of virgin and nanomodified specimens under Mode I fatigue loading. A 40-micron thick layer of Nylon 6,6 nanofibers have been produced and interleaved in carbon fiber-epoxy resin composite laminates; static and dynamic double cantilever tests have been performed to determine delamination growth onset and crack propagation rate vs. maximum energy release rate respectively. Nanomodified specimens exhibited improved delamination resistance during both the tests: delamination toughness increased 130% and cracks propagated 36 to 27 times slower than virgin interfaces. The benefits of the nanointerleave and its working mechanism have been explained using micrographs and SEM images, which revealed a double-stage reinforce mechanism

Mechanical properties of electrospun nanofiber reinforced/interleaved epoxy matrix composites—A review

“…Brugo determined crack growth rate vs energy release rate behavior for Nylon 6, 6 nanofiber reinforced carbon/epoxy composites . Fourteen ply laminates with 40‐μm thick veil were tested at 0.3 loading ratio up to 500 k cycles.…”

Electrospun nanofibers as reinforcement for composite laminates materials – A review

“…• 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.…”

“…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. It is one the most effective reinforce mechanism to hinder crack propagation, for it force the delamination to follow longer and harder paths, sometimes also crossing plies [45].…”

Improvement of the Impact Properties of Composite Laminates by Means of Nano-Modification of the Matrix—A Review

“…The identification of the best factors is very important for conducting a fast and optimized process. For instance, there are different solvent systems for producing Nylon 66 such as pure Formic Acid (FA) [12], mixture of FA/Chloroform [13][14][15] and mixture of FA/Trifluoroethanol (TFE) [16][17][18][19]. The use of the first two solvents results in a very slow electrospinning process (about 0.2-0.3 mL/h), while the third one allows a very fast process with about 0.8-1.2 mL/h [16,20].…”