Parametric Model to Analyze the Components of the Thermal Conductivity of a Cellulose-Nanofibril Aerogel

Cellulose nanofibrils are attractive as an excellent, sustainable material for thermal insulation, when assembled in an aerogel (``solid air'', a gel in which gas has replaced the liquid). To advance beyond trial and error in developing these aerogels, it is important to understand the several contributions to their thermal conductivity $\ensuremath{\kappa}$, as well as $\ensuremath{\kappa}$ for an individual nanofibril. Here an open-cell model is used to obtain this information by fitting the measured $\ensuremath{\kappa}$ of such an aerogel, under atmospheric and vacuum conditions. The results can be used to predict the optimum solid volume fraction and performance of modified fibril networks.