Preparation and characterization of polycarbonate nanocornposites based on surface-modified halloysite nanotubes

Halloysite nanotubes (HNTs) modified by a chemical vapor adsorption (CVA) process remarkably improve the thermal stability of polycarbonate nanocomposites. HNTs were modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPS) and n-octadecyltrimethoxysilane (OTMS) using a CVA process. Both Fourier-transform infrared spectroscopy and thermogravimetric analysis showed that the modifiers were immobilized on the HNT surfaces. Polycarbonate (PC)/HNT nanocomposites were prepared with the modified HNTs by a combination of solution mixing, precipitating and compression molding. The dispersion states of modified HNTs in PC nanocomposites were observed by optical microscopy, scanning electron microscopy and transmission electron microscopy. The storage modulus (E') and thermal stability of the PC nanocomposites were enhanced by the modified HNTs. OTMS-modified HNT/PC nanocomposites showed higher performance than AEAPS-modified HNT/PC nanocomposites due to the stronger affinity of the hydrophobic alkyl groups of OTMS for the polymer matrix.