M. Tajvidi, W. Leng, J.F. Hunt, C. Diop, D. Bousfield, D. Gardner, E. Amini, M. Bilodeau, W. Gramlich
Laboratory of Renewable Nanomaterials, University of Maine,
Keywords: cellulose nanofibrils, binder, wood based panels, large-volume applications
Summary:A key path towards the commercialization of cellulose nanomaterials is to target large-volume applications in commodity products where a successful market introduction could potentially mobilize orchestrated efforts to revitalize the forest products industry. At the Laboratory of Renewable Nanomaterials we have introduced the concept of using cellulose nanofibrils (CNF) as binder in conventional wood based compressed panels . Binder applications take advantage of impressive hydrogen bonding capacity of CNF  and have many other uses . Unlike the traditional use of cellulose nanomaterials as additives in polymer systems that require “dried” materials, no initial drying of CNF is needed in the processes we have developed. These wet applications of CNF provide a closer-to-market possibility to use large volumes of cellulose nanomaterials in commodity applications. In this presentation, we will present our findings in wet-formed particleboard bonded with cellulose nanofibrils (CNF). The effects of density, CNF addition ratio, pressing method, and particle size on the bending strength of the panels were evaluated. With increasing density and CNF addition ratio panels were able to meet low-density and some medium-density modulus of elasticity (MOE) and modulus of rupture (MOR) requirements in ANSI A208.1-2016 standard. In an effort to lower the production cost, we have also shown that lingo-cellulose nanofibrils can be produced directly from wood and can be used as binder in the formulation of traditional fiberboard panels. Thermomechanical pulp (TMP) produced using atmospheric refining was ground to isolate lignocellulose nanofibrils (LCNF). Forty minutes and a specific energy of about 1300 kWh/t were necessary to reach the end-point of the process defined by the presence of 95% fines in the slurry. 100% fines was reached after 90 minutes and 5800 kWh/t. The similarity in structure between pilot-scale produced CNF and LCNF confirmed the negligible effect of residual lignin on the grinding process. The thermal stability of LCNF was 30°C lower compared to CNF due to the lignin influence, but was in the range of processing temperature used for wood composites materials. The effect of using LCNF as adhesive replacement in fiberboard was assessed. Future outlooks, potential issue and methods to implement large volume applications of CNF are discussed.