Preparation and characterisation of poly(vinyl) alcohol (PVA)/starch (ST)/halloysite nanotube (HNT) nanocomposite films as renewable materials

Poly(vinyl) alcohol (PVA)/starch (ST) films (weight ratio: 80/20) were prepared using a solution casting method, in the presence of 30 wt% glycerol (GL) as a plasticiser. Halloysite nanotubes (HNTs) were used as relatively new clay nanofillers to PVA/ST/GL blends for more economical material packaging. HNTs at filler loadings of 0.25, 0.5, 1, 3 and 5 wt% were incorporated to enhance mechanical and thermal properties of resulting PVA/ST/HNT nanocomposites. The tensile strength of such nanocomposites was found to be improved by 20 and 3.4%, respectively, with the inclusion of 0.25 and 0.5 wt% HNTs as opposed to those of PVA/ST/GL blends. However, a decreasing strength trend was observed beyond the HNT loading of 0.5 wt% due to HNT agglomeration, as evidenced by relevant micrographs via scanning electron microscopy (SEM). However, Young’s modulus was enhanced by 148% with the addition of 1 wt% HNTs when compared with PVA/ST/GL blends. X-ray diffraction (XRD) analysis is indicative of slightly intercalated nanocomposite structures formed at low HNT loadings of 0.25–1 wt%. In general, the incorporation of HNTs improved the thermal stability of PVA/ST/GL blends by increasing melting and decomposition temperatures along with the reduction in weight loss

Effects of dispersion and particle-matrix interactions on mechanical and thermal properties of hnt/epoxy nanocomposite materials

Halloysite nanotubes (HNTs), naturally occurring as aluminosilicate nanoclay mineral, have recently emerged as a possible nanomaterial for countless applications due to their specific chemical structure, tubular shape, high aspect ratio, biocompatibility and low toxicity. In this study, HNTs were incorporated into the epoxy resin matrix to improve its mechanical properties and thermal stability. However, heterogeneous size, surface charge and surface hydrogen bond formation, result in aggregation of HNTs in epoxies to a certain extent. Three specific techniques were used to integrate HNTs into neat epoxy resin (NE). The structure and morphology of the embedded nanotubes were confirmed by Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Tensile testing was carried out and the fractured surface of the tested specimen was analysed using scanning electron microscopy (SEM). The thermal stability of the prepared nanocomposite materials was investigated by thermogravimetric (TG) and derivative thermogravimetry (DTG) studies. The obtained results indicated that improved properties of HNTs/epoxy nanocomposite materials were related to the unique properties of well-dispersed HNTs, agglomerate scale, and reduced void presence, and could be controlled by the manufacturing processes