Improved Interlaminar Fracture Toughness and Electrical Conductivity of CFRPs with Non-Woven Carbon Tissue Interleaves Composed of Fibers with Different Lengths

Abstract

Non-woven carbon tissue (NWCT) with different fiber lengths was prepared with a simple surfactant-assistant dispersion and filtration method and used as interleaving to enhance both delamination resistance and electrical conductivity of carbon fiber reinforced plastics (CFRPs) laminates. The toughing effect of NWCT on both Mode I and Mode II interlaminar fracture of CFRPs laminate is dependent on length of fibers, where the shorter carbon fibers (0.8 mm) perform better on Mode I interlaminar fracture toughness improvement whereas longer carbon fibers (4.3 mm) give more contribution to the Mode II interlaminar fracture toughness increase, comparing with the baseline composites, and the toughness increase was achieved without compromising of flexural mechanical properties. More interestingly, comparing with the baseline composites, the electrical conductivity of the interleaved composites exhibited a significant enhancement with in-plane and through-the-thickness direction, respectively. Microscopy analysis of the carbon tissue interleaving area in the laminate indicated that carbon fibers with shorter length can form into a 3D network with more fibers aligned along through-the-thickness direction compared with longer ones. The shorter fibers thus potentially provide more effective fiber bridges, pull-out and matrix deformation during the crack propagation and improve the electric conductivity significantly in through-the-thickness direction.

Effect of Nonwoven Carbon Tissue-Reinforced Epoxy Resin Adhesive Layer on the Single Lap Bonding Strength of Aluminum Alloy Joints

“…The crack propagation path is along the SCFs and turns or divaricates due to the hindrance of the SCFs in the NWCT-reinforced specimen. 30 The adhesive−carbon fiber interface is introduced into the adhesive layer using the NWCT so that the original single adhesive/adherend interface is changed into a double-interface system. When the stress load is transferred in the adhesive layer, it will first be transferred to the NWCT/adhesive resin interface and then to the interface of the adhesive/adherend.…”

“…The failure mode of the NWCT-reinforced adhesive layer specimen before and after aging is the adhesive cohesive failure of Mode 1. The crack propagation path is along the SCFs and turns or divaricates due to the hindrance of the SCFs in the NWCT-reinforced specimen …”

“…Compared with short fiber, NWT or NWCT shows better mechanical properties and homogeneity. At present, many types of scientific research interleave NWCT to the interlaminar toughening of composites, which can significantly increase the mode II fracture toughness of composites. − But so far, it has not been reported that NWT or NWCT is implanted into the adhesive layer to enhance the bonding properties.…”

Interlaminar fracture toughness of carbon/epoxy composites laminates toughened by short carbon fiber

“…One of the major problems limiting the SCF modified epoxy resins is that the fracture toughness enhancement of the intrinsic epoxy resin cannot be effectively transferred to the composite 27 . In terms of SCF interlaminar toughening composites, Xu et al showed that SCF with a length of 0.8 mm performed better in improving mode I IFT than SCF with a length of 4.3 mm, while longer SCF contributed more to mode II IFT 28 . Liu et al used a Nickel‐coated carbon fiber (NiCF) veil for the interlayer toughening material 29 .…”

Effect of Chopped Fibers on the Mode I and Mode II Interlaminar Fracture Toughness of Glass Fiber Reinforced Composites

“…Interleaving is a technique of introducing a new layer between plies of laminates. This new layer can be thermoset or thermoplastic films [18,[25][26][27]35], electrospun nanofiber veils [17,19,21,22,[36][37][38], a layer using spraying/sifting/spreading method [23,24,29,34,39], and dry or prepreg tissue of chopped fibers [16,30].…”