2016 TAPPI International Conference on Nanotechnology for Renewable Materials
Physico-chemical investigation of Cellulose Nanomaterials using NMR relaxation
Dr. David Fairhurst & S.W. Race,
XiGo Nanotools Inc., Bethlehem, PA 18015, USA
Cellulose nanomaterials (CNM) demonstrate great promise for use in a wide array of industrial sectors. For example, the theoretical strength-to-weight performance offered by CNM is outstanding. CNM offer major environmental benefits because they are recyclable, biodegradable and are produced from renewable resources. CNM are being considered for use in a broad array of traditional products such as reinforced composites, adhesives, cosmetic formulations, food packaging, specialty paper, supercapacitors, sensors and electrode materials.
Systems comprising heterogeneous and asymmetric particles present distinctive analytical challenges. There is a need to better characterize CNM with respect to their structure, surface properties, and performance, especially in situ. Electron- and atomic force-microscopy are used but such measurements are not routine and, certainly, are not suited to normal laboratory analysis nor, importantly, to process monitoring.
NMR relaxation is a non-invasive, non-destructive technique that probes the extent and nature of the interface between liquid molecules and any particle surface, irrespective of shape. In general, any changes in the particle-liquid interface such as adsorption or desorption phenomena can be observed. Relaxation can be used to characterize the strength and structure of interactions between any liquid solution and particle surface functional groups. Measurements can be made at virtually any solids concentration, and in almost any fluid media; information is obtained rapidly, and without dilution. Samples can be measured, stored under thermally controlled conditions, and re-analyzed to understand thermodynamic stability. Further, with no moving parts, samples can be readily measured under stop-flow conditions – exceptionally useful for sampling heterogeneous materials.
Using a 13MHz benchtop device optimized to analyze particulate dispersions we will present data on a variety of CNM dispersions that illustrate the versatility of the measurement as a routine laboratory analytical tool and as a process monitoring technique for quality control and assurance.