Effect of the Addition of Natural Rice Bran Oil on the Thermal, Mechanical, Morphological and Viscoelastic Properties of Poly(Lactic Acid)

Abstract

For the first time in this study, the utilization of rice bran oil (RBO) as possible totally eco-friendly plasticizer for poly(lactic acid) (PLA) has been investigated. For comparison, the behavior of soybean oil (SO) has also been analyzed. Both oils are not completely miscible with PLA. However, certain compatibility exists between PLA and (i) RBO and (ii) SO, because demixing is not complete. Although not totally miscible, RBO and SO are able to reduce the viscosity of the PLA+RBO and PLA+SO mixtures, which attests that a small amount of RBO or SO can be successfully added to PLA to improve its processability. Additionally, the mechanical properties of the PLA+RBO and PLA+SO mixtures exhibit trends typical of plasticizer-polymer systems. More interestingly, RBO was found to accelerate the growth of PLA α’-crystals at a low crystallization temperature. This feature is appealing, because the α’-phase presents lower elastic modulus and higher permeability to water vapor in comparison to the α-phase, which grows at high temperatures. Thus, this study demonstrates that the addition of RBO to PLA in small percentages is a useful solution for a faster preparation of PLA materials containing mainly the α’-phase.

3D Printed Parts of Polylactic Acid Reinforced with Carbon Black and Alumina Nanofillers for Tribological Applications

“…The nanocomposites exhibited a slight shear thinning behavior at high angular frequencies due to the macromolecules' orientation and decrease of number of chain entanglements. [59] In addition, higher complex viscosity was observed for nanocomposites with higher content of CB. The highest value was obtained by PLAALM25CB75, probably because of a synergistic effect between nanofillers, which can be explained by the strong interaction between CB and PLA matrix and the adsorption of alumina nanoparticles on the CB surface, as already mentioned.…”