Using multiwalled carbon nanotubes to impart electrical conductivity, particularly in the electrostatic dissipation (ESD) range, to injection moulded polyether ether ketone (PEEK) components

Abstract

The aim of this thesis is to produce injection moulded polyether ether ketone (PEEK) materials with electrostatic dissipation (ESD) properties that match or improve on existing materials without compromising the mechanical properties of PEEK or its processability. Currently commercial materials are heavily filled with micron-scale conductive particles and the material is brittle and difficult to process. Multi-walled carbon nanotubes (MWCNTs), with their excellent electrical and mechanical reinforcing potential and good processability, have been extensively employed in the literature, and increasingly in industry, to enhance the electrical properties of polymers but they have not been examined as potential fillers in injection moulded PEEK to enhance conductivity. This project therefore set out to determine if MWCNTs could be blended into PEEK and moulded into parts with acceptable ESD performance for commercial applications; this included extrusion compounding of MWCNTs into PEEK followed by injection moulding of parts for characterisation. The influence of initial compounding strategy, MWCNT loading and moulding conditions on the structure and properties of the PEEK nanocomposites was determined via a range of techniques including thermal and optical analysis, tensile, impact and electrical conductivity characterisation. Key results reveal that the electrical conductivity of PEEK is significantly improved by MWCNT integration. While an exact match to the conductivity of commercially available ESD material was not achieved it is clear from our results that this is achievable between a loading of 1 wt.% (~10-11 S/cm) and 2 wt.% (~10-5 S/cm) of MWCNTs. The Young's modulus and tensile strength of the PEEK matrix improves with addition of MWCNTs without significantly reducing its ductility and the impact performance is significantly higher (> 50%) than the commercial ESD material. The low loading of MWCNTs in this work results in a more easily processed and a much lighter material (> 20%) than the commercial ESD-PEEK.

Date of Award	Feb 2022
Original language	English
Supervisor	Alistair McIlhagger (Supervisor), Edward Archer (Supervisor) & Eileen Harkin-Jones (Supervisor)