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.

Bioderived and Biodegradable Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Nanocomposites Based on Carbon Nanotubes: Microstructure Observation and EMI Shielding Property Improvement

“…With the incorporation of CNTs, the T c of various PHBV specimens increased, which could be attributed to the CNTs’ effective heterogeneous nucleation capacity during the crystallization process . For the same reason, the χ c of various PHBV specimens accordingly enhanced . One may notice that both enhancements were observed only in the range of CNTs loading between 0 and 2 wt %.…”

“…The crystallization behaviors and thermal transition of various PHBV specimens could provide some significant information for their processing temperature window and final physical properties Figure illustrates the crystallization and melting DSC curves of different PHBV specimens and their relevant thermal parameters are listed in Table .…”

“…22 For the same reason, the χ c of various PHBV specimens accordingly enhanced. 27 One may notice that both enhancements were observed only in the range of CNTs loading between 0 and 2 wt %. However, when the CNT content was above 2 wt %, for the occurrence of agglomeration of CNTs (see Figure 3), such heterogeneous nucleation effects were not further strengthened with the increasing CNT content.…”

“…Montanheiro found that CNT modification has a negative effect on the σ of PHBV specimens, owing to the fact that functionalization reactions would produce defects onto the surface of CNTs and impede the electrical transport . In addition to those stated above, CNTs or functionalized CNTs were also often utilized to modify the mechanical properties of PHBV specimens. , …”

“…21 In addition to those stated above, CNTs or functionalized CNTs were also often utilized to modify the mechanical properties of PHBV specimens. 27,28 Currently, numerous polymer-based nanocomposites filled with CNTs have been reported for the electromagnetic interference (EMI) shielding application, which could be classified into two types: one is petroleum-based nonbiodegradable polymer nanocomposites and the other is biobased biodegradable ones. 29−34 For the first type, some conventional polymers, such as thermoplastic polyurethane (TPU) and polypropylene (PP), were often incorporated with CNTs and widely researched to obtain excellent EMI shielding properties.…”