Abstract
In this work, antistatic, high-performance composites of poly (ether ether ketone) (PEEK) and concentrations of 0.5–7 vol% expanded graphite (EG) were fabricated via twin-screw extrusion and injection moulding at mould temperatures of 200°C. The morphological, electrical, rheological, thermal, mechanical, and wear properties of the composites were investigated. Scanning electron microscope (SEM) images indicate that distribution and dispersion of EG platelets in the PEEK matrix are enhanced at higher EG loadings. The electrical conductivity of the composites with 5 vol% of EG exhibits a sharp rise in the electrical conductivity range of antistatic materials because of the formation of conductive paths. The formation of a three-dimensional EG network led to a rapid increase in the storage modulus of the melt of the 2 vol% of EG-loaded composite at a frequency of 0.1 rad/s and temperature of 370°C. The neat PEEK and composites containing 0.5–5 vol% EG indicated a cold-crystallisation peak in the first heating scan of a non-isothermal differential scan calorimetry (DSC) test and their crystallinity degrees changed slightly. However, after removing their thermal and stress histories, the EG platelets promoted nucleation and increased the PEEK crystallinity remarkably, indicating that annealing of the PEEK composites can improve their mechanical performance. The neat PEEK exhibits the standard tensile and flexural stress-strain behaviour of thermoplastics, and the composites exhibit elastic behaviour initially followed by a weak plastic deformation before fracture. The addition of 5 vol% of EG to PEEK increased the tensile and flexural modulus from 3.84 and 3.55 GPa to 4.15 and 4.40 GPa, decreased the strength from 96.73 and 156.41 MPa to 62 and 118.19 MPa, and the elongation at break from 27.09 and 12.9% to 4 and 4.6%, respectively. The wear resistance of the composite containing 3 vol% EG was enhanced by 37% compared with the neat PEEK.
Highlights
(ether ether ketone) (PEEK) has a variety of promising properties such as high chemical resistance, outstanding mechanical properties, and good thermal and dimensional stabilities due to its aromatic and semicrystalline backbone
Scanning electron microscope (SEM) analysis was performed to examine the morphology of the expanded graphite (EG) platelets of the injected PEEK/EG composites
SEM images show that at lower EG loadings, EG platelets agglomerated and did not distribute well in the PEEK matrix, while with an increase in the EG loading, they were almost uniformly distributed and formed a continuous three-dimensional network. This can be ascribed to the higher shear stress in the processing of the high EG content composites that led to the penetration of the PEEK melt into the pores of the EG honeycomb-like structure and the creation of good mechanical interlockings between the EG galleries and the matrix (Zheng et al, 2004; Li and Chen, 2007)
Summary
(ether ether ketone) (PEEK) has a variety of promising properties such as high chemical resistance, outstanding mechanical properties, and good thermal and dimensional stabilities due to its aromatic and semicrystalline backbone. These properties and the easier processing of PEEK as compared with metals, biocompatibility, and transparency to radiation have increased interest in its usage in industries such as biomedical, aerospace, and automotive. The simultaneous improvement of the wear resistance and electrical conductivity of PEEK by the incorporation of a cost-effective filler using melt mixing is very desirable for industrial applications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
