All-lignocellulosic fiberboard from corn biomass and cellulose nanofibers

Highlights

• CNF addition improves the quality of fiberboards made from corn biomass.

• The incorporation of CNF by 2 wt% is the optimum quantity.

• CNF reinforcement is a good alternative to synthetic resin.

Abstract

In general, fiberboards are made of lignocellulosic fibers with synthetic adhesive to connect between fibers. Synthetic adhesives are usually non-biodegradable constituents and they cause health and environmental troubles. The present study aims to develop fiberboards from corn thermomechanical fibers reinforced with cellulose nanofibers. In this work, corn stalk biomass was used to produce high yield thermomechanical pulp (TMP) that was converted into binderless fiberboards. Cellulose nanofibers (CNF) were also added as reinforcing agent. The mechanical and physical properties of the resulting fiberboards were characterized and compared with commercial high density fiberboard (HDF) containing synthetic adhesives. Fiberboards with 0.5 wt% CNF showed modulus of rupture of 43 MPa, similar to that of commercial HDF. The highest mechanical performance was reached for fiberboards at 2 wt% of CNF, with modulus of rupture of 52 MPa. CNF was found to increase the resistance of the new all-lignocellulosic fiberboards when compared to the products made only with corn stalk fiber, and also when compared with commercial HDF.

Introduction

Fiberboards are fibrous panels made up of lignocellulosic materials joined together with a synthetic binder (American National Standard, 2002). Urea-formaldehyde or phenol-formaldehyde are common resins used in fiberboard manufacturing because they are less expensive compared with other adhesives. However, the formaldehyde emission is one of the most important disadvantages of these resins, since it can potentially cause health and pollution problems. Instead, binderless boards are wood-based composites consisting of particles of lignocellulosic material bonded together without any added resin. Recently, there is a growing request for binderless boards (El-Kassas and Mourad, 2013, Rokiah et al., 2009). In order to meet the market demand and environmental care, several studies have been done to convert fiberboards into binder-free fiberboards by using different methods such as thermotreatments (Anglès et al., 2001, Baskaran et al., 2012, Halvarsson et al., 2009, Huang et al., 2015, Mejía et al., 2014, Pan et al., 2010, Quintana et al., 2009, Rokiah et al., 2009, Saari et al., 2014 Wuzella et al., 2011); the replacement of urea formaldehyde by starch (Abbott et al., 2012); the addition of soybean protein (Ciannamea et al., 2010, Li et al., 2009); pretreating fibers with white-rot fungus (Wuzella et al., 2011); the addition of lignin (Anglès et al., 2001, Mancera et al., 2012, Mejía et al., 2014, Sun et al., 2014, Velásquez et al., 2003); and more lately, by adding of cellulose nanofibers (Cui et al., 2014).

The present study aims to develop fiberboards from thermomechanical fibers produced from corn biomass. Additionally, cellulose nanofibers will be incorporated to improve the mechanical efficiency of the corn fiberboards. Corn biomass will be treated by steaming in a rotary digester, and later mixed with eucalyptus cellulose nanofibers. The final purpose is to produce corn binder-free fiberboards with enhanced properties with respect to commercial fiberboard containing synthetic adhesives.