Catechol‐based co‐deposited carbon fiber surfaces for enhancement of fiber/epoxy composites

Abstract

To improve interfacial adhesion between carbon fiber (CF) and epoxy resin, a low‐cost and environment‐friendly method was developed to treat the CF surface via the bio‐inspired co‐deposition of catechol (Cc) and polyethyleneimine (PEI). It is noteworthy that the deposition process reacts at room temperature with water as solvent, and does not require harsh conditions or the use of toxic reagents. After treatment, the CF/epoxy composites were endowed with excellent mechanical properties and showed increases of 51.9% and 51.7% for flexural strength and ILSS, respectively, in comparison with unsized CF laminates. The analyses of fractured surface morphologies and strengthening mechanism of the composites indicated that the uniformly coated Cc‐PEI on the fiber surface can promote the diffusion and entanglement of the matrix molecular chains and form chemical bonding as well as π‐π stacking, thus effectively improving the interfacial adhesion. In addition, the facile process disclosed in this study can provide a new strategy to not only for CF treating but also expected to be used in the modification of other high performance fiber reinforcement and industrial applications.

Laser‐Triggered Interfacial Generation of ROS Promotes a Rapid Fabrication of Polydopamine Coating

“…The N1s subpeaks at 397.96, 399.77, and 401.30 eV ascribed to -NH 2 , -NH-, and -N═, respectively. [41] These results demonstrated that the formation process of this laser-triggered PDA coating went through oxidation and nucleophilic reaction, along with Michael addition and Schiff base reaction, which agreed with the typical base-induced PDA coating. Further, we tested the time-dependent behavior of N1s.…”

Study on Bone-like Microstructure Design of Carbon Nanofibers/Polyurethane Composites with Excellent Impact Resistance

“…Figure S2 shows that XRD pattern consisted of a broad diffraction peak at 20.72° without any detectable sharp peaks, which indicates the amorphous molecular structure of samples. As is shown in Figure 3 b, a new signal, N1s at 400.1 eV, [ 41 , 42 , 43 ] appears in the spectra of CC-PEI@CNFs, and N1s accounts for 3.35% of CPC-2. Figure 3 c shows three broad peaks at around 280, 322, and 480 nm in the solution, which is suggested as evidence for the cross-linking reaction [ 41 , 42 ].…”

“…As is shown in Figure 3 b, a new signal, N1s at 400.1 eV, [ 41 , 42 , 43 ] appears in the spectra of CC-PEI@CNFs, and N1s accounts for 3.35% of CPC-2. Figure 3 c shows three broad peaks at around 280, 322, and 480 nm in the solution, which is suggested as evidence for the cross-linking reaction [ 41 , 42 ]. Figure S3 shows the N1s pattern of CNFs and CC-PEI@CNFs, and XPS N1s spectrum of CC-PEI@CNFs can be curve-fitted with three peak components at a binding energy of 398.6, 399.9, and 401.4 eV, which correspond to –NH 2 , –R 2 NH, and –N=, [ 43 , 44 ] respectively.…”

“…Besides, for CNFs, the XPS C1s spectrum can be curve-fitted with three peak components at a binding energy of 284.8, 286.6, and 289.0 eV, attributable to the C-C, C-O, and O=C-O species, respectively ( Figure 3 d). However, for CC-PEI@CNFs, the C1s spectra appear at a new peak at 285.5 eV, which represents C-N ( Figure 3 e), which is suggested as evidence for the cross-linking reaction [ 41 , 42 ]. From Figure 3 f, we find that CNFs lose about 6% weight at 800 °C, due to the loss of water and oxide decomposition.…”

Constructing “Soft‐Stiff” Structure on the Surface of Carbon Fiber to Enhance the Interfacial Properties of Its Epoxy Composites

“…The surface structures of different fibers were further confirmed by Raman measurements. As shown in Figure 4b, two typical peaks at 1350–1360 cm –1 and 1590–1600 cm –1 correspond to the D‐band and G‐band, [ 27 ] and their intensity ratio ( I D / I G ) is often used to indicate the structural disorder of carbonaceous materials. [ 25 ] In addition, the peak at 575 cm –1 was caused by the stretching vibration of MnO, and the Raman band at 647 cm –1 belonged to the symmetrical stretching vibration of MnO.…”