Simplification of gel point characterization of cellulose nano and microfiber suspensions

Nanocellulose is an emerging material that needs to be well characterized to control its performance during industrial applications. Gel point (Og) is a convenient parameter commonly used to estimate the aspect ratio (AR) of cellulose nano/microfibers (CNFs/CMFs), providing critical information on the nanofiber network. However, its estimation requires many sedimentation experiments, tedious and time consuming. In this study, a simpler and faster technique is presented to estimate Og, based on one or two sedimentation experiments, reducing the experiments by a factor of at least 2.5. Here, this new methodology is successfully validated by using the Og of different CNF/CMF hydrogels calculated with the traditional methodology, showing an error lower than 7%. The error in the estimation of the AR is lower than 3% in all cases. Furthermore, the two mathematical models currently used to estimate Og, the smoothing spline and the quadratic fit, are compared and the mathematical assumptions improved.