The modification of halloysite nanotubes (HNTs) as fillers is very effective at improving the performance of polymers. A novel modification of HNTs through grafting dodecylamine onto their surfaces was conducted here. Owing to the improvement in dispersibility of HNTs in polytetrafluoroethylene (PTFE), the mechanical properties and wear resistance (in particular) of the dodecylamine-modified HNT-filled PTFE composite were enhanced significantly.

In order to improve the dispersibility of halloysite nanotubes (HNTs) in polytetrafluoroethylene (PTFE), the modification of HNT surfaces was studied with three types of modifiers (polymethyl methacrylate [PMMA], sodium dodecyl sulfate [SDS] and carboxylic acid). The modified HNTs were characterized by Fourier-transform infrared (FTIR) spectrometry, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and contact angle measurements. The HNTs were used to reinforce the mechanical properties of PTFE. The mechanical results indicated that the tensile strength of the modified HNT-filled PTFE nanocomposites (F-HNT/PTFE) improved to an acceptable degree and Young's modulus increased significantly. The tribological results showed that the wear rate of F-HNT/PTFE decreased by 21–82 and 9–40 times compared to pure PTFE and the pristine F-HNT/PTFE, respectively.

Halloysite nanotubes (HNTs)/polytetrafluoroethylene (PTFE) nanocomposites were prepared by the cold compression moulding method. The effects of addition of HNTs (HNTs ‘filling’) on the performances of PTFE were explored using X-ray diffraction, Fourier Transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis which showed that HNTs were well dispersed in the PTFE matrix by means of physical mixing at lower contents of 2–5 wt.%; the introduction of HNTs into PTFE could improve the heat stability of the PTFE. Furthermore, the mechanical and tribological performances of the nanocomposites were measured to examine the filling effect. The tensile strength of the HNTs/PTFE nanocomposites at 2–5 wt.% HNTs content increased by ~3.5% while their wear rates decreased by 55–90% relative to pure PTFE, clear proof of the filling effect of HNTs with a high aspect ratio.