Carbon Fiber Surface Functional Landscapes: Nanoscale Topography and Property Distribution

Abstract

The ultimate properties of carbon fibers and their composites are largely dictated by the surface topography of the fibers and the interface characteristics, which are primarily influenced by the surface distribution of chemical functionalities and their interactions with the matrix resin. Nevertheless, nanoscale insights on the carbon fiber surface in relationship with its chemical modification are still rarely addressed. Here, we demonstrate a critical insight on the nanoscale surface topography characterization of modified novel carbon fibers using high-resolution atomic force microscopy at multiple length scales. We compare the nanoscale surface characteristics relevant to their role in controlling interfacial interactions for carbon fibers manufactured at two different tensions and two distinct chemically functionalized coatings. We used surface dimple (also known as nanopores) profiling, microroughness analysis, power spectral density analysis, and adhesion and electrostatic potential mapping to reveal the fine details of surface characteristics at different length scales. This analysis demonstrates that the carbon fibers processed at lower tension possess a higher fractal dimension with a more corrugated surface and higher surface roughness, which leads to increased surface adhesion and energy dissipation across nano- and microscales. Furthermore, electrochemical surface modification with amine- and fluoro-functional groups significantly masks the microroughness inherent to these fibers. This results in increased fractal dimension and decreased energy dissipation and adhesion due to the high chemical reactivity in the areas of asperities and surface defects combined with a significant increase in the surface potential, as revealed by Kelvin probe mapping. These local surface properties of carbon fibers are crucial for designing next-generation fiber composites with predictable interfacial strength and the overall mechanical performance by considering the fiber surface topography for proper control of interphase formation.

Atomistically informed hierarchical modeling for revisiting the constituent structures from heredity and nano–micro mechanics of sheath-core carbon fiber

“…The simulated microvoid defect chord length is roughly the same order of magnitude as the reported value 13–18 Å from in situ SAXS experiments 5,50 without considering the mesoscopic surface roughness 51 or deep holes, 52 especially for low tensioned fibers. 53 The volume fraction of discrete microvoids domain 1 was approximately extracted through the color level and solved by pixel analysis in ImageJ software. Results indicate that skin–core nano-pores take up about 14.4% and 54.2% of volume fractions, respectively.…”

Interface Engineering of Microporous Polypropylene Membranes for Polyamide Thin-Film Composite Nanofiltration Membranes with Robust Structure and Superior Performance

“…Therefore, it is an issue to synthesize uniform and integral polyamide layers on hydrophobic substrates via interfacial polymerization. To overcome this obstacle, researchers have developed various surface modification methods to hydrophilize the substrates, such as surface coating, − vapor deposition, plasma treatment, , chemical treatment, grafting, and layer-by-layer assembly. , Among these methods, some are limited by the complex operational process, specific devices, or high energy-consumption. Surface coating has been considered as a promising strategy for the characteristics such as simplicity, conformal modification, and easy to large-scale fabrication.…”

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

“…Without sacrificing high performance, the lightweight characteristic has become a constant pursuit of structural materials for the sake of reducing energy consumption and responding to green and low-carbon life . Fiber-reinforced polymer composites, specifically carbon fiber reinforcement, have gained immense popularity thanks to their extraordinary strength-to-weight ratio, integral formation, and design flexibility. , However, delamination is the main cause of composite failure, which is mostly initiated at the interphase owing to the graphitized carbon fiber surface that could not bond well with the polymer . Considering this, chemical functionalization with specific functional groups (by dint of chemical grafting and sizing methods) − and active yet nonspecific groups (in virtue of oxidative methods) , for tailoring the fiber surface is widely employed.…”