Relationships between nanofiller morphology and viscoelastic properties in CNF/epoxy resins

Abstract

This article investigated the rheological behavior of epoxy‐amine resins/carbon nanofibers (CNFs) dispersions and its correlation with the nanofiller morphology. The use of the reactive diluent 1,4‐butandiol diglycidyl ether into the tetraglycidylmethylene dianiline liquid epoxy precursor has proven to be a key in reducing the viscosity of the epoxy matrix. The effect of nanoadditives on the oscillatory shear behavior of the un‐cured epoxy precursor matrix in the liquid state was studied. These nanofillers consist of CNFs as made and after high heat treatment temperature. The inclusion of as made CNFs at 0.5 wt% content had no influence on the Newtonian rheological behavior of the epoxy precursor. The morphological investigation indicated that the as made nanofibers showed a tendency to bend and had functionalized surfaces which determined a large epoxy layer thickness around the nanofibers. Due to these events, the as made CNFs were further apart in the epoxy liquid precursor and, consequently, the rheological percolation network at 0.5 wt% was not formed. Conversely, when the heat‐treated CNFs were used, the rheological results of the epoxy/0.5 wt% CNF dispersion indicated a transition from liquid‐like to solid‐like behavior at low frequencies showing that in this case the 0.5 wt% content of heat‐treated CNFs is higher than the rheological percolation threshold. Indeed, the heat‐treated CNFs exhibited an increase in their “equivalent length” and a smaller thickness of the epoxy layer around the nanofibers so that these heat‐treated CNFs could easily form a percolation network. POLYM. COMPOS., 36:1152–1160, 2015. © 2015 Society of Plastics Engineers

Synthesis of ruthenium catalysts functionalized graphene oxide for self-healing applications

“…This reactive diluent has proven to be effective to reduce the viscosity of epoxy precursors [32,33] allowing to improve handling and ease of processing and to optimize consequently performance properties. The compounds E and B, both containing epoxy-moieties, were obtained by SigmaeAldrich.…”

Electrical conductivity of carbon nanofiber reinforced resins: Potentiality of Tunneling Atomic Force Microscopy (TUNA) technique

“…CNF2500 were dispersed within the epoxy resin at loading rates of 0.05, 0.32, 0.64, 0.8, 1.00, 1.3 and 2% by weight. Epoxy nanocomposites with loads of CNF2500 beyond 1.3% by weight have difficulty in establishing a homogeneous mixture [35,50]. All the epoxy mixtures were cured by a two-stage curing cycle: a first isothermal stage was carried out at the lower temperature of 125°C for 1 h and the second isothermal stage at higher temperatures up to 200°C for 3 h. This curing cycle was chosen because it meets industrial requirements to manufacture the carbon fiber reinforced composites CFRCs (the temperature/time of the first step is lower than the second one to facilitate the CF impregnation before the resin solidification).…”

The effect of the nanotube oxidation on the rheological and electrical properties of CNT/HDPE nanocomposites

“…The formation of a network structure, that leads to an elastic reinforcement and to the transformation from the liquid-like to the solid-like response at low frequencies, has been previously documented for CNTs composites [6][7][8][9][10][11][12][13][14][15][16][17][18][31][32][33][34][35][36][37][38][39] as well as for nanocomposites containing carbon nanofibers [40][41][42][43][44], layered silicates composites [45][46][47][48], graphene [49,50], carbon black [51], and for thermotropic liquid crystalline polymers [52,53]. Compared to traditional fillers [54], nanofillers reach the rheological percolation threshold at much lower concentrations, due to their high aspect ratio and high surface area that means contacts with polymer chains are much greater.…”