Thermoset nanocomposites reinforced by vinyl-functionalized halloysite

In the current study, naturally occurring halloysite nanotube (HNT) is first modified by vinyltriethoxysilane to obtain vinyl-functionalized HNT (HNT-Vinyl). Subsequently, the HNT-Vinyl is added as nanofiller by varying weight from 0 to 8% in the presence of multifunctional methacrylates (bisphenol A-dimethacrylate and triethylene glycol dimethacrylate). Free radical photocrosslinking polymerization of these materials provides the in-situ formation of HNT/thermoset nanocomposites. Comparison of characteristic bands of the nanocomposite components by Fourier transform infrared spectroscopy confirms the presence and covalent bonding of HNT nanofiller in the thermoset matrix. Thermal properties of obtained HNT/thermoset nanocomposites have been compared with neat thermoset as a reference sample using thermogravimetric analysis. Moreover, the existence and dispersion of nanofillers in the nanocomposites have been proved by scanning electron microscopy and transmission electron microscopy. The HNT nanofiller has been detected as agglomerated/non-agglomerated morphology in the thermoset matrix. On the other hand, the addition of HNT-Vinyl to the thermoset matrix has improved the mechanical properties of nanocomposites. Especially, a dramatic increase on tensile strength values has been determined with 4% HNT-Vinyl loading. Tensile strength and elastic modulus values of the corresponding nanocomposite are 4.9 and 1.5 times higher than those of the neat thermoset.

Automated summary

In this study, naturally occurring halloysite nanotube (HNT) was modified by vinyltriethoxysilane and used as nanofiller in the preparation of HNT/thermoset nanocomposites via free radical photocrosslinking polymerization. The presence and covalent bonding of HNT nanofiller in the thermoset matrix were confirmed by Fourier transform infrared spectroscopy. The thermal properties and dispersion of nanofillers in the nanocomposites were analyzed by thermogravimetric analysis and electron microscopy techniques. The addition of HNT-Vinyl improved the mechanical properties of the nanocomposites, especially the tensile strength.