Simultaneous enhancement of electrical conductivity and interlaminar fracture toughness of carbon fiber/epoxy composites using plasma-treated conductive thermoplastic film interleaves

Abstract

Multiwalled carbon nanotube (MWCNT)-doped polyamide 12 (PA12) films with various nanofiller loadings were prepared via a solution casting method to simultaneously improve the electrical conductivity and fracture toughness of carbon fiber/epoxy (CF/EP) composites. The films were interleaved between CF/EP prepreg layers and melted to bond with the matrix during the curing process. To improve the interfacial compatibility and adhesion between the conductive thermoplastic films (CTFs) and the epoxy matrix, the CTFs were perforated and then subjected to a low temperature oxygen plasma treatment before interleaving. Fourier transform infrared (FTIR) spectra results confirm that oxygen-containing functional groups were introduced on the surface of the CTFs, and experimental results demonstrate that the electrical conductivity of the laminates was significantly improved. There was a 2-fold increase in the transverse direction electrical conductivity of the laminate with 0.7 wt% MWCNT loading and a 21-fold increase in the through-thickness direction. Double cantilever beam (DCB) tests demonstrated that the Mode-I fracture toughness (G IC ) and resistance (G IR ) of the same laminates significantly increased by 59% and 113%, respectively. Enhancements of both interlaminar fracture toughness and electrical conductivity are mainly attributed to the strong interfacial adhesion achieved after plasma treatment and to the bridging effect of the carbon nanotubes.

Investigation on cure kinetics of epoxy resin containing carbon nanotubes modified with hyper-branched polyester

“…13 The mean value of a M was used to calculate the kinetic parameters. In eqn (5), the ratio of reaction order, p ¼ m/n as pointed out by Málek, can be replaced by:…”

“…where a Mm is the mean of a M . The kinetic parameters n is obtained from the slope of ln[(da/dT)b e x ] vs. ln[a p (1 À a)] (from eqn (4), (5) and (13)) as well as the kinetic parameter m can be calculated from eqn (13). All of kinetic parameters, E, n and m are listed in Table 3.…”

“…Therefore, it is very important to improve the toughness and to enhance the impact resistance, fatigue behavior and damage tolerance of the material. [3][4][5] In recent years, great efforts have been made to improve the toughness of epoxy thermosets. Toughness implies energy absorption and is achieved through various deformation mechanisms before failure occurs.…”

Effect of structure regulation of hyper-branched polyester modified carbon nanotubes on toughening performance of epoxy/carbon nanotube nanocomposites

“…5,6 Therefore, toughening and modication of epoxy resin has become the focus of current research. 5,[7][8][9] Toughness, achieved through various deformation mechanisms before failure occurs, implies energy absorption. In past years, great efforts have been made to improve the toughness of epoxy thermosets.…”

Simultaneous enhancement of electrical conductivity and interlaminar shear strength of CF/EP composites through MWCNTs doped thermoplastic polyurethane film interleaves

“…In recent years, there is an increasing interest in developing interleaving method to improve interlaminar fracture toughness of composite materials. Various thermoplastic polymers, such as polysulfone (PSF), polyetherimide (PEI), phenoxy, and polyamide (PA) are introduced into the interlaminar resin enriched regions of laminated composites in the forms of particles, films or nanofiber veils. The toughness against delamination fractures has increased to different extent through ductile deformation, void formation and crazing, and other mechanisms.…”