Oxidized multiwalled carbon nanotubes as effective reinforcement and thermal stability agents of poly(lactic acid) ligaments

Abstract

In this study, nanocomposites of poly(lactic acid) (PLA) containing 0.5, 1, and 2.5 wt % oxidized multiwalled carbon nanotubes (MWCNT-COOHs) were prepared by the solved evaporation method. From transmission electron microscopy and scanning electron microscopy micrographs, we observed that the MWCNT-COOHs were well dispersed in the PLA matrix and, additionally, there was increased adhesion between PLA and the nanotubes. As a result, all of the studied nanocomposites exhibited higher mechanical properties than neat PLA; this indicated that the MWCNT-COOHs acted as efficient reinforcing agents, whereas in the nonoxidized multiwalled carbon nanotubes, the mechanical properties were reduced. Nanotubes can act as nucleating agents and, thereby, affect the thermal properties of PLA and, especially, the crystallization rate, which is faster than that of neat PLA. From the thermogravimetric data, we observed that the PLA/MWCNT-COOH nanocomposites presented relatively better thermostability than PLA; this was also verified from the calculation of activation energy. On the contrary, the addition of MWCNT-COOH had a negative effect on the enzymatic hydrolysis rate of PLA.

PLA/sepiolite and PLA/calcium carbonate nanocomposites: A comparison study

“…These properties can be improved by adding nanoparticles to the polymer. Various nano‐reinforcements including layered‐silicate clays,2–6 silica,7, 8 cellulose nanofibers,9–12 nanoTiO 2, 13 nanodiamond,14 nanotube,15, 16 nanographite,4, 17 and nano calcium carbonate18, 19 have been used with the aim of improving thermal, crystallization, mechanical, biodegradability, and melt rheological behaviors of polymers.…”

Physical Properties of Maleated Poly(lactic acid) Composites Containing Different Functionalized Multiwalled Carbon Nanotubes

“…Other findings reported that PLA/MWCNT-COOH nanocomposites exhibited higher tensile strength in a range of 65-86 MPa with the filler concentration of 0.5-2.5 wt% compared to that of the pristine PLA (63 MPa). 24 In contrast, the elongation of the composites tends to decrease as the nanotube concentration is increased, and the nanocomposites show smaller elongation compared to the MA-g-PLA. This is attributed to that the addition of stiff reinforcement can reduce the elongation to break of the matrix because of stress concentration.…”

“…[20][21][22][23] Other approaches involve a direct blending of PLA with functionalized CNTs. [24][25][26][27] Chrissafis et al studied nanocomposites of PLA containing 0.5-2.5 wt% carboxylic-functionalized MWCNTs. 24 It was reported that the nanotubes were well dispersed in the PLA matrix and the adhesion between PLA and the nanotubes was increased.…”

“…[24][25][26][27] Chrissafis et al studied nanocomposites of PLA containing 0.5-2.5 wt% carboxylic-functionalized MWCNTs. 24 It was reported that the nanotubes were well dispersed in the PLA matrix and the adhesion between PLA and the nanotubes was increased. The resultant nanocomposites exhibited higher mechanical properties and thermostability than the neat PLA.…”

Biomaterials and nano-scale features for ligament regeneration

“…Due to the ease of fabrication, carbon nano-fi bers and nanotubes have also been combined with polyhydroxyesters to produce composites with enhanced mechanical properties (Chrissafi s et al ., 2010 ;Mackle et al ., 2011 ) and improved degradation rates (Chrissafi s et al ., 2010 ). In vitro cell response studies to aligned carbon nanotube composites showed fi broblast morphology resembling that of native tissues (Yuen et al ., 2008 ).…”