Novel method of compounding cellulose nanocrystal suspensions into poly(lactic acid) and poly(vinyl acetate) blends

Cellulose nanocrystal (CNC) suspensions were compounded into blends of poly(lactic acid) (PLA) and poly(vinyl acetate) (PVAc) using a novel wet compounding approach in which drying and compounding were carried out simultaneously. The resulting CNC/PLA composites were compared with those produced using a more traditional method of freeze-drying CNC suspensions followed by melt-blending into PLA. CNCs in wet compounded composites appeared to be well-dispersed in the PLA/PVAc blends, and films extruded from these compounds exhibited high transparency compared with melt-blended composites. Gel permeation chromatography indicated that molecular weight degradation due to wet compounding was comparable to that from melt blending. The formulation, including surfactant modified CNCs and PVAc processing aids, played a significant role in the dispersion and properties of the nanocomposites. The elimination of a stand-alone drying step for cellulose nanomaterials can potentially overcome some of the challenges associated with producing thermoplastic cellulose nanocomposites and help advance commercialization of these materials.