Abstract
Composites of poly(l-lactic acid) (PLLA) reinforced by adding inorganic nanotubes of tungsten disulfide (INT–WS2) were prepared by solvent casting. In addition to the pristine nanotubes, PLLA nanocomposites containing surface modified nanotubes were studied as well. Several surface-active agents, including polyethylene imine (PEI), were studied in this context. In addition, other biocompatible polymers, like poly d,l-lactic acid (PDLLA) and others were considered in combination with the INT–WS2. The nanotubes were added to the polymer in different proportions up to 3 wt %. The dispersion of the nanotubes in the nanocomposites were analyzed by several techniques, including X-ray tomography microscopy (Micro-XCT). Moreover, high-temperature rheological measurements of the molten polymer were conducted. In contrast to other nanoparticles, which lead to a considerable increase of the viscosity of the molten polymer, the WS2 nanotubes did not affect the viscosity significantly. They did not affect the complex viscosity of the molten PLLA phase, either. The mechanical and tribological properties of the nanocomposites were found to improve considerably by adding the nanotubes. A direct correlation was observed between the dispersion of the nanotubes in the polymer matrix and its mechanical properties.
Highlights
Poly(lactic acid) (PLA) is a compostable thermoplastic derived from renewable plant sources, such as starch and sugar
The morphology of the crossof the neat poly(L-lactic acid) (PLLA) film and with different concentrations of inorganic nanotube (INT)–WS2 was examined by High-Resolution Scanning Electron Microscopy (HRSEM)
The mechanical properties of PLLA with different weight percentage of INT–WS2 showed a large improvement as the weight percent increased to
Summary
Poly(lactic acid) (PLA) is a compostable thermoplastic derived from renewable plant sources, such as starch and sugar. The Young’s modulus of INT–WS2 is around 150–170 GPa, bending modulus of 217 GPa, tensile strength between 16–22 GPa, and their strain ε > 10% [28,29] Their favorable mechanical properties were attributed to the high degree of crystallinity of the multiwall nanotubes, obtained through high temperature chemical synthesis. Several reports on the effect of nanotubes and fullerene-like nanoparticles of WS2 incorporated in biodegradable/biocompatible polymers such as PLLA [51], poly(3-hydroxybutyrate) (PHB) [52], Poly(3-Hydroxybutyrate-co-3-hydroxyvalerate) (PHVB) [53], and others have appeared. These studies focused on the crystallization process of these thermoplastic polymers. In contrast with other nanoparticle fillers, the addition of the nanotubes did not influence the polymer viscosity and the dynamic rheological parameters
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call