From Graphene to Carbon Fibres: Mechanical Deformation and Development of a Universal Stress Sensor

TL;DR

This paper establishes a universal model linking the mechanical deformation of carbon fibers to the properties of graphene, using Raman spectroscopy to relate strain sensitivity across different CF types.

Contribution

It introduces a universal master plot connecting Raman G peak shifts in graphene and carbon fibers, revealing a common strain sensitivity value.

Findings

Universal G peak strain sensitivity of ~ -5ω0^-1 cm^-1 MPa^-1 for CF and graphene

Developed a model relating CF mechanical properties to graphene structure

Demonstrated the applicability across various CF morphologies

Abstract

Carbon fibres (CF) represent a significant volume fraction of modern structural airframes. Embedded into polymer matrices, they provide significant strength and stiffness gains over unit weight as compared to other competing structural materials. Nevertheless, no conclusive structural model yet exists to account for their extraordinary properties. In particular, polyacrynonitrile (PAN) derived CF are known to be fully turbostratic: the graphene layers are slipped sideways relative to each other, which leads to an inter-graphene distance much greater than graphite. Here, we demonstrate that CF derive their mechanical properties from those of graphene itself. By monitoring the Raman G peak shift with strain for both CF and graphene, we develop a universal master plot relating the G peak strain sensitivity of all types of CF to graphene over a wide range of tensile moduli. A universal value of - average- shift rate with axial stress of ~ -5{\omega}0^-1 (cm^-1 MPa^-1)is calculated for both graphene and all CF exhibiting annular ("onion-skin") morphology.