Effect of three-dimensional to one-dimensional orientation of cellulose nanofiber sizing agents on carbon fibers under magnetic and electric fields on composite material properties.

Nanoparticle-containing sizing agents are essential for the overall performance of high-quality carbon fiber (CF) composites. However, the uneven dispersion of nanoparticles often leads to agglomeration on the surface of CF after sizing, consequently diminishing the material properties. In this study, the properties of cellulose nanofibers (CNFs) that can respond to magnetic and electric fields were utilized to achieve three-dimensional to one-dimensional orientations in CFs containing sizing agents. Cobalt ferrite (CoFe2O4) was utilized to enhance the response of CNFs to a magnetic field, and subsequently, it was combined with an electric field to attain a higher degree of orientation. The occurrence of nanoparticle agglomeration is diminished on CF surface, while establishing a structured network. The flexural strength and thermal conductivity of CF composites treated with CoFe2O4 self-assembled CNF sizing agent exhibit an increase of 54.23 % and 57.5 %, respectively, compared to those of desized CF composites, when subjected to magnetic and electric fields. Consequently, the approach can depolymerize the nano-fillers within the sizing agent and orient it into the carbon fiber under the influence of magnetic and electric fields, effectively improving the mechanical properties and thermal conductivity of the composite material.

Growth of ZnO nanorods/flowers on the carbon fiber surfaces using sodium alginate as medium to enhance the mechanical properties of composites.

The chemical inertness of the carbon fiber (CF) surface results in suboptimal mechanical properties of the prepared composites. To address this issue, we employed a combination of tannic acid and 3-aminopropyltriethoxysilane mixture (TA-APTES) grafted sodium alginate (SA) as a medium to enhance the interfacial properties of composites through the growth of ZnO nanoparticles on CF surfaces. ZnO nanolayers with rod-like and flower-like structures were obtained by adjusting the pH of the reaction system (pH = 10 and 12, respectively). Characterization results show that in comparison with the untreated CF composites, in the flexural strength, flexural modulus, interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) of the as-prepared CF/TA-APTES/SA/ZnO10 (nanorods) composites were improved by 40.8 %, 58.4 %, 44.9 % and 47.8 %, respectively. The prepared CF/TA-APTES/SA/ZnO12 (nanoflowers) composite showed an increase in flexural strength, flexural modulus, ILSS and IFSS by 39.8 %, 63.6 %, 47.3 % and 48.2 %, respectively. These positive results indicate that the ZnO nanolayers increase the interfacial phase area and fiber surface roughness, thereby enhancing mechanical interlocking and load transfer between the fibers and resin matrix. This work provides a novel interfacial modification method for preparing CF composites used in longer and more durable wind turbine blades.