Assessing the integrity of CFRPs through nanomechanical mapping: the effect of CF surface modification

Abstract

Abstract. The purpose of this study is to assess the effect of CF surface modification in enhancement of the wetting properties of carbon fibers in order to improve the adhesion force between the fiber and the polymer matrix; for this, the integrity of CFRPs through nanomechanical mapping was evaluated. The surface of commercial carbon fibers was functionalized through cyclic voltammetry in aqueous electrolyte solutions of H2SO4, in the presence of acrylic acid, methacrylic acid, acrylonitrile and Nvinylpyrrolidone monomers. The produced surface modified carbon fibers were embedded in epoxy resin. Elastic modulus nanoindentation mapping was performed in order for elastic modulus to be calculated, as a qualitative assessment of fibre -matrix interaction. For this, a grid protocol was set up for the integrity assessment of CFRPs through nanomechanical mapping.

Comparative Physical–Mechanical Properties Assessment of Tailored Surface-Treated Carbon Fibres

“…Microstructural studies proved the formation of the corresponding polymeric coating at the fibre surface. The most prospective polymer coating is the PMAA, since it leads to maximum composite properties with treated carbon fibres (an increase of 124% in tensile strength), and does not cause a reduction of the mechanical properties of the fibre itself, which comes in accordance with our recent studies [ 30 , 31 ]. Under the modification of carbon fibres by low-pressure plasma treatment, CF’s tensile strength is reduced, while under modification by active screen plasma, all five-minute-treated CFs show increased tensile strength.…”

Applying Machine Learning to Nanoindentation Data of (Nano-) Enhanced Composites

“…A standard three-sided pyramidal Berkovich tip was used, with an average curvature radius of 100 nm [13]. In all measurements, a total of 64 indents were performed by applying a square 8 × 8 grid, with spacing of 5 µm to avoid any indentation-to-indentation interaction [6,25]. The measurement environment was characterized by 45% humidity content, and 23 • C ambient temperature.…”

“…In detail, datasets of untreated CFRPs were used as reference, while CFRPs with CFs surface modification were included. Surface modification contained the introduction of oxygen species on the fiber surface, the attachment of monomers (sizing formulations), and the growth of CNTs, which are commonly adapted in literature [3][4][5][6][7][8]. Seed of random numbers was called to achieve a statistically unbiased estimation.…”

“…Techniques with the potential of industrial application such as "green" electroplating technology, thermal spraying, and laser cladding introduce a nanometer's thin film on carbon fibers (CFs) surface. The subsequent incorporation of functional groups and novel sizing formulations improves the interphase and consequently, the CFRP mechanical properties [4][5][6]. Moreover, reinforcement with nanomaterials, such as CNTs growth on CFs is reported to effectively deal with the brittle fracture mechanism of the epoxy-based CFRPs similarly to aforementioned processes [3,7,8].…”