Toward Industrially Feasible Methods for Following the Process of Manufacturing Cellulose Nanofibers

Abstract

a Nanocellulose is a recently developed form of cellulose that has the potential to be used in many different industries, ranging from food to high-performance applications. This material is commercially manufactured through the homogenization of chemical pulps, but the process is energy-consuming and is still an important subject for development. Simple, robust methods are required for the quality control and optimization of industrial nanocellulose production. In this study, a number of different methods, based on different principles of monitoring the manufacture of cellulose nanofibers were evaluated and compared for five different nanocellulose qualities, both for their resolution and robustness/ease. Methods based on microscopy, light scattering, centrifugation, and viscosity were examined and all appeared useful for observing the manufacturing process during its initial stage. However, only methods based on centrifugation, turbidity, and transmittance yielded reliable data for the entire manufacturing process. Of these methods, transmittance measurement may be the best candidate for routine use because the method is simple, rapid, and only requires spectrophotometer equipment.

Microfibrillated lignocellulose (MFLC) and nanopaper films from unbleached kraft softwood pulp

“…Although the fibril geometries appeared to be similar for different MFLC suspension supernatants, there was a difference in fibril weight fraction in supernatant. In previous studies (Moser et al 2015;Naderi et al 2015;Wågberg et al 2008), the gravimetric yield of the cellulose nanofibrils was determined from centrifugation and used as an indication of fibrillation efficiency. For that reason, the ratio of supernatant to pre-centrifugation concentration was multiplied by the volume fraction of the MFLC supernatant and this quantity was considered as the nanofibril yield.…”

Towards optimised size distribution in commercial microfibrillated cellulose: a fractionation approach

“…Furthermore, these techniques are not only time-consuming and require skilled operators, but they also often require rather complicated sample preparation, creating uncertainty as to whether the microscopic image is representative of the bulk material, and the material is complex to analyse if there is a broad size distribution. In the second category, an extensive set of techniques has been developed to measure for example turbidity, optical transmittance, dynamic light scattering, rheology, water retention value, specific surface area, nanofraction by centrifugation and mechanical properties of films (Kangas et al 2014;Moser et al 2015;Desmaisons et al 2017). In a recent paper, Desmaisons et al 2017used a large number of these indirect measurements to calculate an overall quality index to compare different grades of MFC, and they found a good correlation between this index and the expected degree of fibrillation and the energy consumption of their process.…”

Specific Surface Area Increase during Cellulose Nanofiber Manufacturing Related to Energy Input

“…Enzymatic hydrolysis was performed at 25 ECU g -1 using 490 kWh ton -1 (heating) to deactivate the enzymes, according to the procedure described by Moser et al 2015. Fibrillation was achieved in a microfluidizer (M-110EH, Microfluidics Corp., Westwood, USA) at a pulp concentration of 15 g L -1 with a pressure of 900 Bar for the first pass in 400/200 µm chambers, corresponding to 1.5 MWh ton -1 and 1600 Bar for the second and subsequent passes in 200/100 µm chambers, corresponding to 3.2 MWh ton -1 per pass.…”

“…Transmittance and nanofiber yield was shown to be related to the degree of disintegration and is here utilized to follow the disintegration process (Moser et al 2015).…”