XNBR-grafted halloysite nanotube core-shell as a potential compatibilizer for immiscible polymer systems

Halloysite nanotubes (HNTs) grafted with carboxylated nitrile byutadiene rubber (XNBR) were synthesized via a sol-gel method. The HNTs as an inorganic cores were pre-treated with 3-Glycidoxypropyl trimethoxysilane, then successfully coated with the XNBR as an organic shell. The properties of XNBR-grafted HNTs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results suggested that the XNBR grafted to the surfaces of HNTs successfully. Then the TPE nanocomposites based on polyamide-6 (PA6) and nitrile butadiene rubber (NBR) containing various XNBR-grafted and pristine HNTs were prepared via a direct melt mixing method. The morphology, mechanical, dynamic mechanical and rheological properties of the prepared TPE nanocomposites were investigated. The results show that the XNBR-grafted HNTs can effectively improve the morphology and mechanical properties of the PA6/NBR TPEs. The morphology study of the prepared nanocomposites show that the effect of XNBR-grafted HNTs on the size reduction of NBR phase is markedly more effective than the pristine HNTs and rose by 50% in the same concentrations. Mechanical measurements show that the Young's modulus of the TPE nanocomposites rose by 60% in just 7 wt% of XNBR-grafted HNT loading. The results indicate that the introduction of HNT/XNBR core-shells into the PA6/NBR TPEs can enhances the interfacial interactions and provides a more fine rubber phase morphology and controlled mechanical properties in comparison with the accordingly TPE nanocomposites containing pristine HNTs.