Study on the Construction of Dopamine/Poly(ethyleneimine)/Aminoated Carbon Nanotube Multilayer Films on Aramid Fiber Surfaces to Improve the Mechanical Properties of Aramid Fibers/Epoxy Composites

Ting Xu; Jin Tian; Lizhou An; Yumin Jiao; Qin Yin; Yefa Tan

doi:10.1021/acsomega.2c03390

Study on the Construction of Dopamine/Poly(ethyleneimine)/Aminoated Carbon Nanotube Multilayer Films on Aramid Fiber Surfaces to Improve the Mechanical Properties of Aramid Fibers/Epoxy Composites

ACS Omega. 2022 Sep 29;7(40):35610-35625. doi: 10.1021/acsomega.2c03390. eCollection 2022 Oct 11.

Authors

Ting Xu¹, Jin Tian¹, Lizhou An¹, Yumin Jiao², Qin Yin¹, Yefa Tan¹

Affiliations

¹ College of Field Engineering, Army Engineering University of PLA, Nanjing210007, Jiangsu, China.
² Unit 94789 of PLA, Nanjing210018, Jiangsu, China.

Abstract

To improve the mechanical properties of aramid fiber (AF) reinforced epoxy resin (EP) composites without damaging the strength of the AF body, in this paper, poly(ethyleneimine) (PEI) and aminoated carbon nanotubes (NH₂-CNTs) were successfully deposited on the AF surface layer by layer using poly(dopamine) (PDA) as the initial layer. The modified aramid fibers PDA-AF, PEI-PDA-AF, and NH₂-CNTs-PEI-PDA-AF were prepared. The microstructure and chemical composition of the AF surface at different modification stages were systematically characterized. The interfacial properties, mechanical properties, and strengthening mechanism of AF surface-modified composites were studied. The results showed that with the successful deposition of PDA, PEI, and NH₂-CNTs layer by layer, the interfacial properties and mechanical properties of the composites gradually improved. Among them, NH₂-CNTs-PEI-PDA-AF showed the best strengthening effect. Compared with the unmodified aramid fiber (R-AF), the monofilament tensile strength of NH₂-CNTs-PEI-PDA-AF increased by 8.1%, the contact angle with EP decreased by 21.9%, and the interface energy and adhesion energy increased by 115 and 21.4%, respectively. Compared with R-AF/EP, the interlaminar shear strength (ILSS), bending strength, and tensile strength of NH₂-CNTs-PEI-PDA-AF/EP were increased by 75, 44.5, and 14.9%, respectively. The significant improvement of the interface properties and mechanical properties between NH₂-CNTs-PEI-PDA-AF and EP can be attributed to the introduction of a large number of amino active groups in the NH₂-CNTs-PEI-PDA coating layer on the AF surface, which strengthens the chemical-bond cooperation between the AF and EP matrix. At the same time, a large number of NH₂-CNTs deposited on the surface effectively increased the surface roughness of AF, improved the mechanical meshing between the AF and EP matrix, and then improved the contact angle, surface energy, and interface bonding strength between the AF and EP matrix. Moreover, a large number of NH₂-CNTs on the surface of AF also modified and enhanced the EP in the interface region, which could make the load more effectively transfer from the resin to the fiber, so that AF could carry the load more uniformly, significantly improving the mechanical properties of NH₂-CNTs-PEI-PDA-AF/EP.