CNC dispersion in PLA and PBAT using two solvents: morphological and rheological properties

摘要

Cellulose nanocrystals (CNCs) were dispersed via solution casting in amorphous (A) and semi-crystalline (SC) poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT). The protocol, optimized following the Hansen solubility parameter theory, relies on binary mixtures of tetrahydrofuran and dimethyl sulfoxide for the polymers and CNCs, respectively. First highlighted through atomic force microscopy, good filler dispersion and distribution were confirmed by a decrease of the linear viscoelastic region and significant increases of the complex viscosity, storage modulus, and apparent yield stress of the nanocomposites with CNC content, specifically at low frequencies. CNC percolation thresholds of 1, 0.3, and 0.3 wt% were determined in A-PLA, SC-PLA, and PBAT, respectively. These are the lowest to be reported in the literature until now. While PLA retained solvent traces, leading to a significant plasticizing effect, solvent removal was complete in PBAT. It was attributed to the crystallization of PBAT at the drying temperature (70 degrees C).