Effect of Atmospheric-Pressure Plasma Treatments on Fracture Toughness of Carbon Fibers-Reinforced Composites

Abstract

In this study, nano-scale fillers are added to epoxy matrix-based carbon fibers-reinforced composites (CFRPs) to improve the mechanical properties of multi-scale composites. Single-walled carbon nanotubes (SWCNTs) used as nano-scale fillers are treated with atmospheric-pressure plasma to introduce oxygen functional groups on the fillers’ surface to increase the surface free energy and polar component, which relates to the mechanical properties of multi-scale composites. In addition, the effect of dispersibility was analyzed through the fracture surfaces of multi-scale composites containing atmospheric-pressure plasma-treated SWCNTs (P-SWCNTs) under high load conditions. The fillers content has an optimum weight percent load at 0.5 wt.% and the fracture toughness (KIC) method is used to demonstrate an improvement in mechanical properties. Here, KIC was calculated by three equations based on different models and we analyzed the correlation between mechanical properties and surface treatment. Compared to the composites of untreated SWCNTs, the KIC value is improved by 23.7%, suggesting improved mechanical properties by introducing selective functional groups through surface control technology to improve interfacial interactions within multi-scale composites.

Roles of Small Polyetherimide Moieties on Thermal Stability and Fracture Toughness of Epoxy Blends

“…Here, all the DGEBA/PEI blends exhibit excellent linear relationships between the K IC and the G IC . Thus, we confirmed that the PEI particles in the epoxy matrix act as stress concentrators to absorb the external energy and mitigate the crack growth [41][42][43][44][45][46]. 7a,d, neat DGEBA displayed a regular fracture surface, which is the typical characteristic of a brittle fracture.…”

“…The mechanical properties, including the K IC and G IC , of the DGEBA/PEI blends are indicated in Figure 6 d. Here, all the DGEBA/PEI blends exhibit excellent linear relationships between the K IC and the G IC . Thus, we confirmed that the PEI particles in the epoxy matrix act as stress concentrators to absorb the external energy and mitigate the crack growth [ 41 , 42 , 43 , 44 , 45 , 46 ].…”

Effect of Ambient Plasma Treatments on Thermal Conductivity and Fracture Toughness of Boron Nitride Nanosheets/Epoxy Nanocomposites

“…Moreover, the diffraction patterns of the PBNNS-1 and PBNNS-7 are similar to that of the pristine BNNS, each exhibiting a diffraction peak at 2 θ = 45° due to the (100) crystal plane, thereby indicating that these three samples have the same characteristic crystalline structures. However, the XRD pattern of the PBNNS-10 is different from that of the pristine PBNNS, PBNNS-1, and PBNNS-7 samples, thus confirming that the crystalline structure of BNNS is destroyed by excessive plasma-treatment (i.e., more than 10 min), as has been observed previously [ 45 , 46 , 47 ].…”

Construction of Mussel-Inspired “Inorganic–Organic” Hybrids onto a Cylindrical Carbon Fiber via Green and Rapid Manufacturing toward Enhanced Interfacial Adhesion of Composites

“…The deconvoluted XPS C 1s curves of the CF in Figure a possess three peaks of C–C, C–N/C–O, and OC–O with a content of 46.82, 47.35, and 5.83% at 284.8, 285.8, and 290.3 eV, respectively . In Figure b–d, the OC–O unit vanishes, but the CO functionality appears at 286.4–286.7 eV after surface coating, which mainly results from the quinone monomer provided by PDA. In Figure b–d, CF-hybrid30 has the highest active carbon content of up to 74.62% (the sum of C–N/C–O and CO units), which echoes the peak sum of O and N contents (22.25%) in Table .…”