Assembly-Dependent Interfacial Property of Carbon Nanotube Fibers with Epoxy and Its Enhancement via Generalized Surface Sizing

TL;DR

This paper investigates how the assembly characteristics of carbon nanotube fibers influence their interfacial shear strength with epoxy and explores various surface modification techniques to enhance this property, offering a generalized approach for different CNT structures.

Contribution

It introduces a comprehensive understanding of assembly-dependent interfacial properties and proposes generalized surface sizing methods for improving CNT fiber-epoxy interfaces.

Findings

Interfacial shear strength depends on twisting and densification levels.

Surface modifications can significantly enhance interfacial bonding.

Generalized treatments modify surface or create interphases inside CNT fibers.

Abstract

In building up composite structures using carbon nanotube (CNT) fibers, the fiber-to-matrix interfacial shear strength (IFSS) is one of the most important issues. Originating from the assembly characteristics of CNT fiber, the IFSS strongly depends on the fiber's twisting level and densification level. Furthermore, there are rich ways to modify the fiber surface and thus enhance the IFSS, including the physical and chemical modification on fiber surface, the infiltration of matrix resin into CNT fiber, and the introduction of silane coupling agent. A new feature differing from carbon fibers is that all these treatments either change the fiber's surface structure or form a several-hundreds-nm-thick interphase inside rather than around the fiber. These "generalized" treatments obviously extend the common concept of surface sizing and can be used for various forms of CNT assembly structures.