Influence of different functionalization methods of multi-walled carbon nanotubes on the properties of poly(L-lactide) based nanocomposites

Abstract

This paper presents influence of the type of carbon nanotube functionalization on properties of poly(L-lactide) (PLLA) based nanocomposite materials. For this purpose surface modifications of multi-walled carbon nanotubes (MWCNTs) were performed by chemical and irradiation techniques, while thermo gravimetric analysis, UV-Visible and Fourier-transform infrared (FT-IR) spectroscopies confirmed successful covalent functionalization. Series of PLLA bionanocomposites with different contents of functionalized MWCNTs (0.7; 1.6; 2.1 wt%), were synthesized via ring-opening solution polymerisation of L-lactide. FT-IR analysis confirmed that grafting of Llactide, under controlled condition, is possible to perform starting from the surface of functionalized MWCNTs. From differential scanning calorimetry results it was concluded that even low contents of chemically and irradiation functionalized MWCNTs had a significant effect on thermal properties of the prepared nanocomposites, raising the values of melting and glass transition temperatures. Thermogravimetric analysis (TGA) has shown that the degradation onset temperature for composites with chemically functionalized MWCNTs, was much higher than that for the neat poly(L-lactide) sample and composites with irradiation functionalized MWCNTs. Morphology studies by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that poly(L-lactide) covered surfaces and separated functionalized MWCNTs. Good dispersion of carbon nanotubes in polymer matrix enabled conductivity of synthesized materials, as determined by conductivity tests.

Influence of montmorillonite/carbon nanotube hybrid nanofillers on the properties of poly(lactic acid)

“…may be traced to perturbation of the PLA stereoregularity that is defined by enthalpy or entropy of the isomer units causing the PLA crystal structure to show minute melting temperature changes (Molinaro et al, 2013). The slight increase in melting temperature can also be attributed to the rearrangement of polymer chain that becomes more effective owing to the nanofillers high surface energy (Vukić et al, 2019).…”

A study of polylactic Acid/K2SiF6:Mn4+ composite luminescent materials: design, preparation, and properties

“…In the IR spectrum of polylactic acid (PLA), the blue lines indicate that the absorption peak at 1756 cm −1 corresponds to the stretching vibration of C=O, while the peaks at 1189 cm −1 and 1131 cm −1 represent the stretching vibrations of C-O, confirming the presence of ester groups. Additionally, peaks between 2900 and 3000 cm −1 are attributed to the stretching vibration of C-H, the peak at 1455 cm −1 corresponds to the deformation vibration of C-H, and the peak at 1382 cm −1 is a characteristic peak of methyl, further confirming the structure of polylactic acid [22,23]. Importantly, the IR spectrum of the KSF@PLA composite shows characteristic peaks of both components, represented by dashed lines in the figure 6.…”