Processing strategies for cellulose nanocrystal/polyethylene-co-vinyl alcohol composites

- Three processing techniques were investigated to disperse CNCs in a thermoplastic matrix.
- Polarized optical microscopy was used to evaluate the degree of CNC dispersion obtained.
- A multi-step protocol increased CNC dispersion in a thermoplastic matrix.
- Changes in polymer microstructure were observed when CNCs were well dispersed.

Cellulose nanocrystals (CNCs) have garnered significant attention due in part to the remarkable properties of crystalline cellulose displayed at the nanoscale coupled with its availability from renewable resources. However, challenges exist in dispersing CNCs in thermoplastic polymers and assessing CNC dispersion. The purpose of this research was to investigate the impact different processing protocols had on CNC dispersion in two polyethylene-co-vinyl alcohol (EVOH) matrices and the resulting microstructure of the nanocomposites. Three processing strategies were proposed: a melt processing technique, a solution casting technique, and a combination of solution casting followed by melt processing. Polarized optical microscopy images of the nanocomposites showed that improved CNC dispersion and changes to the nanocomposite microstructure were observed when the multi-step protocol was implemented. Additionally, changes in microstructure as a function of comonomer ratios of EVOH suggested CNC dispersion changed as a result of differences in polymer-particle compatibility.

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