Study on multistage anodization for high‐modulus carbon fiber

Abstract

Because of the strong chemical inertness of high‐modulus carbon fiber (HMCF), the surface treatment of HMCF becomes less effective. In this work, multistage anodization method was applied to modify HMCF. NH4HCO3 and (NH4)2SO4 were used as electrolytes to study the influence of electrolyte type on the oxidation effect in the multistage oxidation process. The HMCF was treated by multistage anodization in the following three ways: NH4HCO3 → NH4HCO3, (NH4)2SO4 → (NH4)2SO4, and NH4HCO3 → (NH4)2SO4. In order to compare with the multistage anodization methods, HMCF was also anodized by NH4HCO3 and (NH4)2SO4 using single anodization method, respectively. The treated HMCFs were characterized in detail using X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM), and dynamic contact angle analysis, respectively. The results of XPS exhibited that HMCF modified by multistage anodization showed more functional groups on its surface. More sp2 hybridized bonds were converted into sp3 hybridized bonds after modification by multistage anodization, especially when (NH4)2SO4 was used as electrolyte. The results of SEM/AFM indicated that HMCF modified by multistage showed a greater surface roughness. Interlaminar shear strength (ILSS) was used to observe the interfacial properties of HMCF between epoxy resin. The results showed that ILSS of untreated carbon fiber composite was only 27.3 MPa; it was increased to 71.8 and 78.6 MPa after treated with single anodization by NH4HCO3 and (NH4)2SO4, respectively. After modification by multistage anodization, the ILSS increased in different degrees compared with single anodization method. Especially, the ILSS reached 93.1 MPa when the method of using NH4HCO3 followed by (NH4)2SO4 was used to treat HMCF.

Effect of Microstructures of Carbon Nanoproducts Grown on Carbon Fibers on the Interfacial Properties of Epoxy Composites

“…The surface energy of the CF can well reflect the wetting state of the CF and the polar polymer matrix. 49 So, the surface energy was calculated by measuring the dynamic contact angles of the CF with deionized water and diiodomethane. As indicated in Figure 6a, compared with the bare CF, the contact angles of CF-CNFs in both liquids became smaller.…”

“…Meanwhile, good wetting can allow the polymer matrix to penetrate the surface of the CF, forming an effective mechanical interlock and achieving a good combination of the CF and the matrix. The surface energy of the CF can well reflect the wetting state of the CF and the polar polymer matrix . So, the surface energy was calculated by measuring the dynamic contact angles of the CF with deionized water and diiodomethane.…”

Παρασκευή τροποποιημένων προτύπων σύνθετων υλικών ινών άνθρακα/εποξειδικής ρητίνης και μελέτη της διεπιφάνειας με χρήση φασματοσκοπίας Raman

“…Οι συγκεκριμένες ίνες ήταν μη τροποποιημένες ίνες άνθρακα χαμηλού μέτρου ελαστικότητας, με διάμετρο 4.7 μm. Η επιλογή ινών χαμηλού μέτρου ελαστικότητας έγινε στοχευμένα, μιας και όσο μεγαλύτερη η θερμοκρασία ενανθράκωσης και ειδικά γραφιτοποίησης τόσο πιο χημικά αδρανής γίνεται η επιφάνεια τους, δυσχεραίνοντας έτσι την πρόσδεση ενεργών ομάδων [107]. Επιπροσθέτως, οι ίνες χαμηλού μέτρου ελαστικότητας είναι αυτές με την μεγαλύτερη παραγωγή παγκοσμίως, το μικρότερο κόστος, καθώς και την πιο ευρεία χρήση [33].…”