In-situ polymerization of aliphatic-aromatic polyamide nanocomposites in the presence of Halloysite nanotubes

摘要

Nanocomposites consisting of semi-aromatic polyamide (PA) and pristine or alkali activated halloysite nanotubes (HNT or mHNT, respectively) were synthesized by the in-situ interfacial polymerization method. The condensation reactions were carried out between isophthaloyl dichloride in hexane and triethylenetetramine in water containing different amounts of HNT or mHNT. The interactions and crystallinity of the nanocomposites were studied by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis, respectively. Development of hydrogen bonds between the functional groups of PA and hydroxyl groups of nanotubes was indicated by FTIR spectroscopy. According to the XRD analysis, the addition of HNT and mHNT nanotubes increased the crystallinity of the PA. This was ascribed to the role of nanotubes as nucleating agents in the PA matrix. Thermal resistance and char residue of PA, as revealed by thermogravimetric analysis, were enhanced by incorporating both HNT and mHNT and the latter was more effective in this regard. Furthermore, while the addition of pristine HNTs decreased the glass transition temperature (Tg) of the PA, the Tg could be increased by about 5 degrees C, in the presence of 5 wt% of mHNTs. Finally, the facilely activated mHNT nanotubes were found to be highly efficient in improving the thermal and structural properties of semi-aromatic PAs.