Key Factors Limiting Carbon Nanotube Yarn Strength: Exploring Processing-Structure-Property Relationships

Abstract

Studies of carbon nanotube (CNT) based composites have been unable to translate the extraordinary load-bearing capabilities of individual CNTs to macroscale composites such as yarns. A key challenge lies in the lack of understanding of how properties of filaments and interfaces across yarn hierarchical levels govern the properties of macroscale yarns. To provide insight required to enable the development of superior CNT yarns, we investigate the fabrication-structure-mechanical property relationships among CNT yarns prepared by different techniques and employ a Monte Carlo based model to predict upper bounds on their mechanical properties. We study the correlations between different levels of alignment and porosity and yarn strengths up to 2.4 GPa. The uniqueness of this experimentally informed modeling approach is the model's ability to predict when filament rupture or interface sliding dominates yarn failure based on constituent mechanical properties and structural organization observed experimentally. By capturing this transition and predicting the yarn strengths that could be obtained under ideal fabrication conditions, the model provides critical insights to guide future efforts to improve the mechanical performance of CNT yarn systems. This multifaceted study provides a new perspective on CNT yarn design that can serve as a foundation for the development of future composites that effectively exploit the superior mechanical performance of CNTs.

Molecular-Level Engineering of Adhesion in Carbon Nanomaterial Interfaces

“…8 It is thus not surprising that the mechanical properties of composites derived from carbon nanomaterials fall short of the properties of their constituents. [11][12][13][14][15] Van der Waals-driven inter-filament interactions thus appear to present a significant bottleneck in carbon nanomaterial composite design.…”

“…14,[25][26][27] Consequently, it is difficult to isolate improvements in inter-filament interactions based on top-down studies of composites alone.…”

“…enhanced adhesion leads to enhanced shear, it is important to account for multiple modes of interfilament failure, especially in composites such as CNT yarns which have great variation in alignment 14,72. The effect of functionalization on nanoscale adhesion of rougher graphitic interfaces (e.g.…”

Superstructured Assembly of Nanocarbons: Fullerenes, Nanotubes, and Graphene

“…The twisting speed was also expected to affect the yarn structures where the slowly spun yarns exhibited increased alignment and decreased porosity over the quickly spun yarns; therefore, they have better mechanical properties. 181 What is more interesting is that Shang et al accomplished a series of distinctive work where they overtwisted a CNT film to obtain a spring-like CNT rope with superstretchability up to 285% of strain ( Figure 7c). 180 Through controlling the fashion and level of overtwisting, the configuration of a twisted film could even vary among doublehelical, 182 partial-helical, 183 and highly entangled structures.…”

Fractal carbon nanotube fibers with mesoporous crystalline structure

“…Thirdly, the production of these fibres in semi-industrial quantities 13 and fast pace of development application 14,3 gives testimony of their technological relevance. The hierarchical structure of CNT fibres has been studied mainly by electron microscopy analysis 15 , including inspection of FIB-sections 16,17 . These techniques reveal the inner structure of the porous CNT fibres, but as a qualitative description constrained to a small sample volume.…”