Oxidation time effects of multiwalled carbon nanotubes on thermal, mechanical, and cure kinetics of epoxy‐based nanocomposites

Abstract

In this work, multiwalled carbon nanotubes (MWCNT) were oxidized in a mixture of sulfuric and nitric acid (3:1 v/v) using two distinct times (9 and 18 hours). The effects of different oxidation levels and concentrations of MWCNT on curing kinetics, thermal, and mechanical properties of bisphenol A diglycidyl ether nanocomposites were studied. The nanocomposites were produced using in situ polymerization technique at two different volume fractions (0.15% and 0.50% v/v) without using solvents. X-ray photoelectron spectroscopy results indicated that MWCNT were in fact oxidized and just 9 hours of acid treatment showed a greater amount of oxygen on the MWCNT surfaces. Results of differential scanning calorimetry and dynamic mechanical analysis showed small variations in the glass transition temperatures of the nanocomposites, indicating alterations in the quality of the interphase matrix/ carbon nanotubes. Concerning the thermogravimetric analysis results, the most thermally stable samples were those containing 0.15% v/v of pristine and 18 hours of oxidized MWCNT, which also had the highest stiffness of all nanocomposites. Finally, the cure kinetics of nanocomposites is fairly represented by Kamal and Sourour's semiempirical model with an autocatalytic behavior at 100 C and 120 C, but decelerated at 140 C.

Investigation of effects of extreme environment conditions on multiwall carbon nanotube‐epoxy adhesive and adhesive joints

“…Besides that, the low density, a significant aspect ratio and a large surface area make them potential structures to reinforce composite materials. [ 14–17 ]…”

“…[1,4,11] Carbon nanotubes (CNTs) were discovered in 1991 by Ijima and since then, they have been gaining a lot of attention due to their excellent mechanical, electrical, and thermal properties. [11][12][13][14] CNTs have covalent bonds between their carbon atoms and exhibit exceptional mechanical properties (elastic modulus is about 1 TPa and tensile strength corresponding to 50-500 GPa). Besides that, the low density, a significant aspect ratio and a large surface area make them potential structures to reinforce composite materials.…”

“…Besides that, the low density, a significant aspect ratio and a large surface area make them potential structures to reinforce composite materials. [14][15][16][17] The dispersion of nano reinforcements in the matrix, in order to obtain cluster-free mixtures, and a good strength between the nanofiller and epoxy interfaces are the main factors that affect the performance of nanocomposite adhesives. [1,4,18] Other aspects that influence adhesive performance are the thickness of the adherent, the roughness of the surface adherent, the thickness of the bond line and the wettability of the adhesive over the surface where it is applied.…”

Poly(acrylated epoxidized soybean oil)‐modified carbon nanotubes and their application in epoxidized soybean oil‐based thermoset composites

“…Typical physicochemical methods are surface functionalization such as hydroxylation, acid modification, [ 36 ] and diamine modification, [ 31,37 ] which can effectively inhibit the reagglomeration of CNTs during the curing process owing to the higher surface energy than the pristine CNTs. In addition, N ‐isopropylacrylamide, [ 38 ] polystyrene, [ 39 ] and copolymer of acrylic acid and acrylamide [ 40 ] have been grafted onto CNTs by the addition–fragmentation chain‐transfer reaction (RAFT), showing superior dispersion effects of CNTs than monofunctional treatment.…”

Formulation of interfacial parameter in Kolarik model by aspect ratio of carbon nanotubes and interfacial shear strength to simulate the tensile strength of carbon‐nanotube‐based systems

“…The well-dispersed carbon nanotubes (CNTs) in the matrix cause the good reinforcement due to large CNT surface area and matrix-CNT physical interaction. [1][2][3][4][5][6][7][8] Additionally, a small concentration of nanoparticles such as CNTs within the polymer nanocomposites induces the significant changes in the conductivity, heat dissipation, thermal constancy and flame retardancy. [9][10][11][12][13][14][15][16][17][18][19][20] Polymer CNT nanocomposites can be applied in electronics, photovoltaic devices, biosensors, superconductors and electromechanical actuators.…”