Recovery of yerba mate (Ilex paraguariensis) residue for the development of PLA-based bionanocomposite films

Abstract

Yerba mate (Ilex paraguariensis) residue (YM) was used as starting material for the production of mate extract nanoparticles through an organic solvent free process. The TGA and FTIR analysis revealed the loss of hemicellulose structures that lead to lignocellulosic based mate nanoparticles (mateNP). Mate extract nanoparticles were added to plasticized PLA matrices with acetyl(tributyl citrate) (ATBC) by melt blending approach. Flexible and optically transparent bionanocomposite films were obtained. The combination of ATBC and mate extract mainly increased the material crystallinity. Mate extract nanoparticles protect the polymer matrix from thermal degradation suggesting that mateNP conserve the well-known antioxidant properties of YM, as it was verified by the determination of the total polyphenols content (TPC = 41 ± 1 mg of gallic acid/g YM). ATBC improved the processability and increased the flexibility up to 80% in ternary PLA-ATBC-mateNP. The ternary PLA-ATBC-mateNP bionanocomposites presented some UV light blocking effect. In addition, all bionanocomposite films displayed appropriate disintegration in compost in around 1 month suggesting their potential applications as biodegradable films.