The role of halloy site on crystallinity, ion conductivity, thermal and mechanical properties of poly(ethylene-oxide)/halloysite nanocomposites

Halloysite nanotubes were applied as an inorganic filler to prepare poly(ethylene-oxide)/halloysite (PEO/halloysite) nanocomposites for the purpose of increasing the ion conductivity of PEO matrix. The resulting PEO/halloysite nanocomposites were characterized by X-ray diffraction (XRD), Fourier Transfer infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), ion conductivity test, thermogravimetry analysis (TG) and mechanical properties test. SEM and TEM micrographs confirmed the good dispersion of halloysite nanotubes in PEO matrix. FTIR spectroscopy showed that the interaction between PEO and halloysite changed the ether oxygen vibrational modes of PEO. XRD and DSC results indicated that the PEO crystallinity gradually decreased with the increment of halloysite concentration. Meanwhile, the reduced PEO crystallinity promoted the improvement of ion conductivity and the maximum value (3.8x10(-5)S/cm) appeared at a halloysite concentration of 20wt%. The formation of amorphous region around halloysite is beneficial for the Li+ ion conduction. Furthermore, the tensile strength of PEO/halloysite nanocomposites was enhanced when halloysite was introduced into the polymer matrix with filler loading no more than 10wt%.