Covalently γ-aminobutyric acid-functionalized carbon nanotubes: improved compatibility with PHBV matrix

Abstract

The improvement of compatibility between carbon nanotubes (CNTs) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was achieved using CNT functionalized with γ-aminobutyric acid (GABA). The efficiency of the CNT functionalization with GABA was evaluated by X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FT-IR), Raman spectroscopy, and transmission electron microscopy (TEM). The PHBV/CNT nanocomposites were produced in the molten state with the addition of 0.5 wt% of CNT (pristine, oxidized and functionalized with GABA) and characterized concerning the Izod impact strength tests. The impact fracture morphologies were analyzed using scanning electron microscopy. The results showed that GABA was covalently attached to CNT, resulting in the detection of nitrogen in the XPS survey, the shift of carbonyl peak wavelength on FT-IR, and a higher degree of structural disorder, detected by Raman and observed in TEM images. The impact strength was not significantly affected by the introduction of CNT; however, the impact fracture mechanism was changed from fragile to ductile when CNT was functionalized with GABA. These results are promising for the production of environmentally friendly nanocomposites with superior properties.