Polylactide/acetylated nanocrystalline cellulose composites prepared by a continuous route: A phase interface-property relation study

• A ‘continuous route’ has been developed to prepare PLA/NCC composites.
• Solvent-assisted centrifugation can replace dialysis and freeze drying.
• Strong interactions between m-NCC and PLA lead to better interfacial adhesion.
• The composite with m-NCC shows evident strain-scaling overshoot behavior.
• The composite with m-NCC has better strength than the one with pristine NCC.

A ‘continuous route’ was developed in this work for the preparation of nanocrystalline cellulose (NCC) filled polylactide (PLA) composites. It combines several separated steps, including extraction of NCC, surface acetylation of NCC, and final composite preparation, into a continuous process, without traditional freeze drying. The obtained PLA composites were then studied in terms of phase interface structure, rheological and mechanical properties. The results reveal that surface acetylation of NCC can improve its affinity to PLA evidently. The thickened interfacial layer makes the system filled with modified NCC show lower percolation threshold than the one filled with pristine NCC; and the former presents a typical strain-scaling stress overshoot behavior in the start-up shear flow because the network structure of modified NCC presents stronger characteristics of self-similarity. The phase interface adhesion also plays an important role in the mechanical behavior of PLA/NCC composites, which is further revealed by the nanomechanical analysis using atom force microscopy.