Benchmarking Cellulose Nanocrystals: From the Laboratory to Industrial Production

Abstract

The renewability, biocompatibility and mechanical properties of cellulose nanocrystals (CNCs) have made them an attractive material for numerous composite, biomedical and rheological applications. However, for CNCs to shift from laboratory curiosity to commercial applications, researchers must transition from CNCs extracted at the bench scale to material produced at an industrial scale. There are a number of companies currently producing kilogram to ton per day quantities of sulfuric acid-hydrolyzed CNCs, as well as other nanocelluloses, as described herein. With the recent intensification of industrially produced CNCs, the variety of cellulose sources, hydrolysis methods and purification procedures, characterization of these materials becomes critical. This has further been justified by the past two decades of research which demonstrate that CNC stability and behaviour is highly dependent on surface chemistry, surface charge density and particle size. This work outlines key test methods that should be employed to characterize these properties to ensure a “known” starting material and consistent performance. Of the sulfuric acid-extracted CNCs examined, industrially produced material compared well with laboratory-made CNCs, exhibiting similar charge density, colloidal and thermal stability, crystallinity, morphology and self-assembly behaviour. In addition, it was observed that further purification of CNCs, using Soxhlet extraction in ethanol, had minimal impact on nanoparticle properties and is unlikely to be necessary for many applications. Overall the current standing of industrially produced CNCs is positive suggesting that the evolution to commercial scale applications will not be hindered by CNC production.