In this study, under the same conditions, two different nanoparticles, namely, titanium dioxide (TiO2) and polyhedral oligomeric silsesquioxane (POSS) were added to the poly(lactic acid) (PLA) matrix via the solution casting technique. Morphological analysis showed that POSS had a better distribution within the PLA matrix. However, rheological analysis revealed the stronger influence of TiO2 on shear viscosity values, and a more notable viscosity upturn at moderate to high inclusions of TiO2 within the low shear rate zone. On the other hand, POSS was found to act as a lubricant even at a content of 3 wt% which was attributed to the very small dimensions of POSS. Such lubricating role, found from rheology, caused a boost in the crystallinity of PLA based on differential scanning calorimetry results. Moreover, it was found that TiO2 had an adverse effect on the crystallinity of PLA which was ascribed to the hindered motions of PLA chains upon addition of moderate to high inclusions of TiO2. The results of this study emphasize the crucial role of nanoparticle type and content on the properties of PLA.
Synergistic effects of organo-modified Mg-Al layered double hydroxide (LDH) and triethyl citrate (TEC) on the properties of poly(lactic acid) (PLA) were demonstrated. PLA/LDH nanocomposites in the absence and presence of TEC were fabricated via solution casting technique. Morphological analysis revealed that as the LDH concentration increases, the number of aggregations is also increased; however, introduction of TEC considerably enhanced the dispersion quality of LDHs. Differential scanning calorimetry results showed that the addition of LDH and TEC had no significant influence on the crystallinity of nanocomposites obtained from solution casting. In contrast, once the samples were cooled from melt, the concurrent use of LDH and TEC led to a dramatic enhancement in the crystallinity of PLA ( X c = 55.5%). Moreover, the LDH nanoparticles counterbalanced the adverse effects of plasticization by TEC leading to enhanced toughness of the final nanocomposites. LDH had also a positive influence on thermal stability of PLA, indicating the heat-insulating role of LDH particles. In conclusion, the concurrent use of LDH and TEC could extend the applicability of PLA especially in food packaging applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.