Abstract
Tungsten disulfide (WS2) nanotubes (NTs) are examined here as a filler for polylactide (PLA) for their ability to accelerate PLA crystallization and for their promising biocompatibility in relevant to biomedical applications of PLA-WS2 nanocomposites. In this work, we have studied the structural and thermal properties of PLA-WS2 nanocomposite films varying the concentration of WS2 NTs from 0 (neat PLA) to 0.6 wt%. The films were uniaxially drawn at 90 °C and annealed at the same temperature for 3 and 10 min. Using wide angle x-ray scattering, Raman spectroscopy and differential scanning calorimetry, we probed the effects of WS2 NT addition on the structure of the PLA films at various stages of processing (unstretched, stretching, annealing). We found that 0.6 wt% of WS2 induces the same level of crystallinity in as stretched PLA-WS2 as annealing in neat PLA for 10 min. These data provide useful insights into the role of WS2 NTs on the structural evolution of PLA-WS2 composites under uniaxial deformation, and extend their applicability to situations where fine tuning of PLA crystallinity is desirable.
Highlights
IntroductionPolylactic acid or polylactide (PLA) is a polymorphic semicrystalline polymer synthesized from renewable sources that finds applications in diverse fields (food packaging, biomedical devices, drug delivery systems) due its properties of biocompatibility and biodegradability [1]
Polylactic acid or polylactide (PLA) is a polymorphic semicrystalline polymer synthesized from renewable sources that finds applications in diverse fields due its properties of biocompatibility and biodegradability [1]
The UNST PLA-Tungsten Disulfide (WS2) nanocomposite films show a uniform dispersion of WS2 NTs in PLA both at the lowest (0.1%, Fig. 2a) and highest (0.6%, Fig. 2b) concentration of NTs
Summary
Polylactic acid or polylactide (PLA) is a polymorphic semicrystalline polymer synthesized from renewable sources that finds applications in diverse fields (food packaging, biomedical devices, drug delivery systems) due its properties of biocompatibility and biodegradability [1]. The applications of this polymer are often limited by its slow crystallization rate, low crystalline degree and Loffredo et al Functional Composite Materials. Despite these advantages, to the best of our knowledge, only a few studies are reported in literature on PLA-WS2 nanocomposites, mainly focused on thermal properties of samples obtained by melt-mixing [21,22,23,24,25]. To the best of our knowledge, only a few studies are reported in literature on PLA-WS2 nanocomposites, mainly focused on thermal properties of samples obtained by melt-mixing [21,22,23,24,25] These studies show that WS2 NTs remarkably influence the kinetics of nucleation and growth of the PLA during the cold crystallization. On the other hand only our previous work [25] reports on the crystallization process induced by stretching PLA-WS2 films at temperatures above the glass transition of PLA (Tg ~ 55–65 °C) but the effect of the WS2 concentration on the crystallization of PLA was not analyzed at the time
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