Abstract: High-performance thermoplastics are lightweight and possess excellent mechanical properties over a wide temperature range. Composites of these materials and carbon nanotubes are expected to enhance mechanical performance while providing thermal and electrical conductivity. Polyether ether ketone (PEEK) is a lightweight, bioinert, high-performance thermoplastic with a wide range of applications in different fields, such as aerospace and biomedical devices. Sulfonated polyether ether ketone (SPEEK), which is obtained through sulfonation of PEEK, is a promising material for replacing traditional perfluorosulfonic acid membranes due to its excellent thermal stability, mechanical properties, and proton conductivity. Owing to their superior physical properties, carbon nanotubes (CNTs) can be introduced into PEEK and SPEEK matrices in order to further improve their conformances, opening up new perspectives for the development of the next generation of high-performance multifunctional materials.
Functionalization of CNTs provides a good approach to developing superior composite materials with enhanced mechanical properties. This process may enable interactions between the polymer matrix and CNTs to be controlled by using different functional groups attached to the nanotubes.
In this study, we present the covalent functionalization of pristine multi-walled carbon nanotubes (P-MWNTs) with poly(ether ether ketone) (SPEEK) chains, employing hexane diamine as an interlinking molecule. Both pristine and functionalized MWNTs (F-MWNTs) were then used to create PEEK/CNT and SPEEK/CNT composites. We used FTIR and NMR spectroscopy to confirm the covalent attachment of the SPEEK chains to the MWNTs and SEM and TEM to characterize the morphology of the functionalized tubes and composites. We evaluated the composites in terms of their structure, mechanical properties, and fracture morphology.
Our results show that SPEEK/F-MWNT composites with 2% F-MWNTs by weight exhibited a 7.1% improvement in their tensile modulus compared to SPEEK/MWNTs. However, the tensile modulus of PEEK/F-MWNTs increased by only 1.2%, while their tensile elongation decreased drastically.
